People who are faced with a new diagnosis of cancer frequently turn to the internet to learn about treatment. Although there is good and reliable information about cancer and cancer treatment on the internet, it is much more common for people to find websites promoting various natural and alternative treatments for cancer as opposed to medically proven treatments such as surgery, radiation, chemotherapy and immunotherapy. Is there evidence that any of these alternative treatments work as well as or better than traditional cancer treatment?
This post will explore the most commonly recommended natural and alternative cancer treatments and present the evidence, if any, that any of them work.
CBD and THC
There is some evidence in tissue culture studies that cannabinoids like CBD and THC inhibit cancer cells. There have been some limited clinical trials in humans using cannabinoids as treatment. None of these trials has shown any beneficial effect on any cancers in humans.
Chinese Herbal Medicines
Traditional Chinese medicine uses a completely different framework than western medicine for health and disease. It has been used and developed for thousands of years. It focuses on restoring natural balance of the opposing forces of yin and yang. Treatment is individualized based on the imbalance diagnosed by the practitioner. In China, traditional Chinese medicine is frequently used as an adjunct to cancer treatment with surgery, chemotherapy and immunotherapy. Combinations of herbs are used as well as things like acupuncture and qigong. There is some evidence that the some of the herbs used in traditional Chinese medicine have some anticancer properties, but because of the individual nature of treatment it is almost impossible to do randomized trials. There is no good evidence that traditional Chinese herbal medicines alone successfully treat any cancers. There is evidence that people in China who use traditional Chinese medicine as an adjunct to other cancer treatments have fewer side effects from anticancer drugs and have better quality of life during treatment.
Ayurvedic Medicine
Another old (5000 year old) system from India that also teaches that disease is due to imbalance that can be corrected with traditional Indian herbal medicines. There are no clinical trials that show the Ayurvedic medicine cures or treats any cancers.
Special Diets
Many types of diets have been proposed to treat cancer. There is no evidence that any dietary changes treat any cancer. Plant based diets have been shown to decrease the risk of getting certain cancers, but there is no evidence plant based diets successfully treat any cancer.
Other unproven and disproven cancer treatments
There are numerous other alternative or natural cancer treatments that have been proposed by many different groups. They are in fact too numerous to mention separately in this post. There is an excellent Wikipedia article that has a comprehensive list of unproven and disproven cancer treatments. Here is a link to that web page: List of unproven and disproven cancer treatments.
Bottom Line
People who use natural and alternative cancer treatments tend to substitute those for proven medical treatments like surgery, chemotherapy and immunotherapy. As a result, people who use these therapies as an alternative to proven treatments have quicker progressions of cancer and die sooner than people who use proven therapies. Some alternative therapies used as an adjunct to proven therapies may improve quality of life during treatment. Because some herbal medicines can interact with chemotherapy drugs, it is important that your cancer treatment doctor knows that you are using one of these alternative therapies as an adjunct to the treatment he/she is giving you for your cancer.
First, let me be clear about the definition of cancer screening. Screening for cancer is done for people who feel well and have no symptoms that suggest they might have cancer.The goal is to detect cancer early, before you have symptoms, so that hopefully it is easier to treat and cure.
If you have symptoms of cancer, then tests such as mammograms or colonoscopy are for diagnosis of a disease, not screening. If you are a woman who has a breast lump or abnormal uterine bleeding, or a man with a lump in the testicle, or anyone who has rectal bleeding or difficulty swallowing food, or feeling full after just a little food, you need to see your doctor right away and be tested for cancer. Here is a link to a web page from UCSF that has a more comprehensive look at symptoms of cancer for which you should see your doctor: 17 Cancer Symptoms You Shouldn’t Ignore.
In this post I am going to write about the available screening tests for cancer. For many cancers there are no good screening tests. A good screening test has to meet several criteria. The first is that it detects a kind of cancer that responds better to treatment when detected early. There are other criteria for a good screening test as well. Here is a link to a web page from the American Medical Society Journal of Ethics that talks about all the criteria for a good screening test: What Makes a Screening Exam “Good”?
I will discuss how well each of them work and how well they fit the criteria for a good screening test. I will also write about the risks of getting cancer screening tests (there are some substantial risks).
Cervical Cancer Screening (and Prevention)
Screening for cervical cancer is the poster child for an effective screening test. It is inexpensive, has no significant risk and detects both cervical cancer and pre-cancerous changes. It develops slowly, so it is an ideal cancer for screening. Early detection leads to much more effective treatment even before cancer develops. Since the 1940’s, when the pap smear was invented, death from cervical cancer has decreased by over 70%.
We have learned a lot about cervical cancer since the 1940’s. We now know that cervical cancer is caused by certain strains of the wart virus, otherwise known as HPV (human papilloma virus). The recommendation used to be that women should have a pap smear every year starting after beginning sexual intercourse. We now know that women under 21 most often clear HPV on their own, and there is no reason to do pap smears before age 21. If the pap smear is normal and the HPV test is negative, then for women 30-65 years of age, it is not necessary to do another one for five years. Women over 65 who have had two previous normal pap smears can stop cervical cancer screening.
Not only can the pap smear and HPV test detect cervical cancer early, but they can detect pre-cancerous changes that can be treated before cervical cancer develops. Even better, there is now a vaccine that prevents HPV and therefore cervical cancer altogether. It is called Gardisil, and should be given to adolescent girls and boys before the age they start having sexual intercourse.
Like other screening tests, most women will not benefit from cervical cancer screening. We would have to do pap smear and HPV screening on 1,140 women for ten years to prevent one death from cervical cancer. That means that 1,140 out of every 1,141 women will not benefit from cervical cancer screening,
Breast Cancer Screening
Mammograms are the primary and most studied screening test for breast cancer. Breast cancer is not as ideal for screening as cervical cancer, because some breast cancers develop very rapidly and can spread aggressively between mammography screenings. That means that some women die from breast cancer even if they get regular mammograms. Mammograms also have a high false positive rate, which can lead to more invasive unnecessary tests such as breast biopsies. The false positive rate for any kind of mammogram, including the newer 3D mammograms is 50% over 10 years!
Mammograms do save lives, but a lot fewer than people think. Here is a table from the US Preventive Services Task Force website that shows the benefits and harms of mammograms every two years for every 1000 women screened.
There are a few things to notice about this table. First, almost all the benefit in lives saved by screening is in the 50-74 age group but more false positives, unnecessary biopsies and overdiagnosis occurs in the group that starts mammography at age 40. The other thing to notice is the number of overdiagnosed breast cancers (overdiagnosed means that these tumors would never result in illness or death from the cancer) are much larger than the number of lives saved in each age category.
What this table says is that 125 women need to be screened with mammography to save one life from breast cancer. That is a great number! On the other hand, for every 47 women screened by mammography one woman gets overdiagnosed with breast cancer that would never harm her. That is a terrible number!
Given all this information, what should women do? Here are the US Preventive Services Task Force recommendations as of 2016. These recommendations are currently being updated, but the new recommendations are not available yet. The USPSTF recommends mammograms every other year, rather than every year. Every other year mammograms cut the risk of false positives in half, but result in the same number of lives saved.
The USPSTF recommends biennial screening mammography for women aged 50 to 74 years.
B
Women aged 40 to 49 years
The decision to start screening mammography in women prior to age 50 years should be an individual one. Women who place a higher value on the potential benefit than the potential harms may choose to begin biennial screening between the ages of 40 and 49 years. . For women who are at average risk for breast cancer, most of the benefit of mammography results from biennial screening during ages 50 to 74 years. Of all of the age groups, women aged 60 to 69 years are most likely to avoid breast cancer death through mammography screening. While screening mammography in women aged 40 to 49 years may reduce the risk for breast cancer death, the number of deaths averted is smaller than that in older women and the number of false-positive results and unnecessary biopsies is larger. The balance of benefits and harms is likely to improve as women move from their early to late 40s. . In addition to false-positive results and unnecessary biopsies, all women undergoing regular screening mammography are at risk for the diagnosis and treatment of noninvasive and invasive breast cancer that would otherwise not have become a threat to their health, or even apparent, during their lifetime (known as “overdiagnosis”). Beginning mammography screening at a younger age and screening more frequently may increase the risk for overdiagnosis and subsequent overtreatment. . Women with a parent, sibling, or child with breast cancer are at higher risk for breast cancer and thus may benefit more than average-risk women from beginning screening in their 40s.
C
Other groups recommend more intensive screening, but screening younger women and screening every year results in less than half a percent more lives saved and markedly increases the harms of screening including false positives and overdiagnosis. My feeling is that the USPTF recommendations make the most sense for women.
Prostate Cancer Screening
Screening for prostate cancer with the PSA (prostate specific antigen) is the most controversial of the cancer screening tests. Overdiagnosis with the PSA test is a huge problem. Autopsy studies done on men who died of other causes find that by age 80 more than half the autopsies show prostate cancer. Many, perhaps most prostate cancers grow so slowly that they will never cause any symptoms. More men die with prostate cancer than from prostate cancer. Overdiagnosis leads to radical prostatectomy for tumors that would never cause symptoms or death. Surgery for overdiagnosed tumors results in permanent urinary incontinence for half of men and sexual dysfunction for most of them. On the other hand, prostate cancer kills one out of every 41 men in the US. A good screening test for aggressive prostate cancer would be a wonderful thing. Unfortunately at this point we do not have such a test.
The US Preventive Services Task Force reviews all the available studies of screening tests and makes recommendations based on that evidence. Here is that review for the PSA test if 1000 men are screened with the PSA test annually for13 years,
Number of Men Affected
Men invited to screening
1000
Men who received at least 1 positive PSA test result
240
Men who have undergone 1 or more transrectal prostate biopsies
Men who initially received active treatment with radical prostatectomy or radiation therapy
65
Men who initially received active surveillance
30
Men who initially received active surveillance who went on to receive active treatment with radical prostatectomy or radiation therapy
15
Men with sexual dysfunction who received initial or deferred treatment
50
Men with urinary incontinence who received initial or deferred treatment
15
Men who avoided metastatic prostate cancer
3
Men who died of causes other than prostate cancer
200
Men who died of prostate cancer despite screening, diagnosis, and treatment
5
Men who avoided dying of prostate cancer
1.3
What this table shows is that of 1000 men screened for 13 years, there will be 100 men diagnosed with prostate cancer, but only 1 life saved as a result of screening and 2 other men who avoid metastatic prostate cancer. The cost of that life saved will be 97 men overdiagnosed with prostate cancer and 220 men that have a prostate biopsy. This is not a pleasant procedure and can sometimes result in complications such as infection, as indicated by the 2 men out of the 220 men that were biopsied that were hospitalized because of the biopsy. Five men out of the 1000 died from prostate cancer anyway despite screening, diagnosis and treatment,
African American men and men with a strong family history of aggressive prostate cancer are at substantially higher risk for aggressive prostate cancer. It is worth considering screening for this group. Men at average risk are more at risk for harm than help from prostate cancer screening, at least with the tests we have available now. The USPTF recommendation is that prostate cancer screening is an individual decision and should be discussed with your doctor.
Colorectal Cancer Screening
Colorectal cancer if caught early is almost 100% curable, but if it is not discovered until it invades the intestinal wall, the cure rate gets progressively worse.
Unlike breast cancer and prostate cancer, which have only one kind of screening test, there are a number of different screening tests for colon cancer. They each have advantages and disadvantages.
FOBT (Fecal Occult Blood Test)
This is the oldest test and also the one that has been studied the most. It is also the least expensive ($5-$10). People who do this test every year, and who have a colonoscopy if they have a positive test have reduced deaths from colorectal cancer by about 27%. That means that out of 1000 people who screen annually with FOBT, there will be 270 fewer deaths from colorectal cancer than people who do not do screening.
The biggest problem with this test is that it has a fairly low sensitivity of 50%, which means it will miss half of early colorectal cancers. It also has a fairly low specificity of 78%, which means that about 1/4 of the tests will be false positives.
FIT (Fecal Immunochemical Test)
This newer test is only positive for blood coming from the colon. That makes both the sensitivity and the specificity higher than FOBT. It is also fairly inexpensive (the home test costs about $25)
The sensitivity of the FIT test is about 75%, which means it will miss about 25% of early colorectal cancers. The specificity of the FIT test is about 90%, which means that the false positive rate is only 10%. Because the FIT test is relatively new, there are no randomized controlled trials of lives saved by FIT tests vs no screening. Estimates based on computer models suggest that annual FIT testing with colonoscopy for positive tests would reduce deaths from colorectal cancer by 74%! That means that of 1000 people who screen with the FIT test and get colonoscopy for positive tests, deaths from colorectal cancer will be reduced from 1782 deaths to 457 deaths.
There are several different kinds of FIT tests. Some require sending a stool sample to a lab, but the home test is just as good and is less expensive. The one that seems to work the best is from Pinnacle Biolabs. Here is a link to their website where you can order a test: Second Generation FIT® 1 Pack.
Cologuard
Cologuard is the only commercially available DNA test. It measures the specific DNA shed by cancer cells. It is actually a combination test and includes a FIT test as well. This increases the sensitivity, but decreases the specificity, which means that the Cologuard test has a higher false positive rate than the FIT test alone. It is also very expensive, about $600 per test. A stool sample has to be collected and sent to the lab. Computer modeling suggests that deaths from colon cancer for 1000 people would be reduced from 1782 deaths to 1143 deaths. Not nearly as good as the FIT test alone.
Colonoscopy
Although some groups consider colonoscopy to be a screening test, many organizations feel that colonoscopy should be used only when another screening test is positive. People who are at high risk of colon cancer should probably have colonoscopy as a screening test. Colonoscopy done every ten years, with follow-up exams every 3 to 5 years when polyps were found, would reduce deaths from 1782 deaths to 624 deaths.
Colonoscopy is the most sensitive and specific test, but also carries much more risk as a screening test. Serious complications (bleeding or perforation) occur in 44 people out of every 10,000. 3 people out of 100,000 die from colonoscopy. The average number of colonoscopies to result in one serious complication is 225. It is also very expensive (average cost $1,700). It may seem counterintuitive that FIT testing saves more lives, but that is because it is easy to do FIT testing every year and screening colonoscopies are done only every 10 years. One advantage of colonoscopy is that it reduces the chance of getting colon cancer by identifying and removing pre-cancerous polyps.
Lung Cancer Screening
For a long time we had no good screening test for lung cancer. Annual chest x-rays were shown to be worthless for lung cancer screening. Now there is a screening test for lung cancer. It is a low radiation dose CT scan. It should be done every year, but only for people aged 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years.
False positives are a huge problem with lung cancer screening. Of people who get a positive result, 97% of those will be a false positive, meaning no cancer will be found on further testing. Further testing may include a needle biopsy of the lung, which can result in a collapsed lung.
The number needed to screen to prevent 1 lung cancer death is about 300. The number needed to harm (false positives or over diagnosis is 19. Although lung cancer screening with low dose CT does save lives, it comes at a substantial cost of false positives and overdiagnosis.
Common Cancers with No Good Screening Test
There are no good screening tests for ovarian cancer, uterine cancer, pancreatic cancer, esophageal cancer, leukemia, or Hodgkin’s disease (cancer of the lymph nodes. Many of these cancers are treatable once they are found, but they are found because of symptoms, not because of screening.
Galleri test
This is an update to this post, which I just published. Galleri is a new blood test that detects DNA shed by cancer cells. The company claims that it will detect 50 different types of cancer. Although this technology is promising, it is not yet ready for prime time. It is very good at detecting advanced cancer, but not very good at detecting stage 1 cancers when they are most treatable. There is also a high false positive rate of about 30%. Hopefully this technology will improve. If that happens, it will be a game changer with regard to cancer screening.
Bottom Line
If you are higher risk for any of the cancers for which we have screening tests, then getting screened is something you should do. If you are at average or low risk, screening tests are unlikely to help you and may harm you. Everyone should be alert for red flag symptoms that mean you might have cancer. The purpose of this post is not to discourage cancer screening, but to give you information that you should have when making a decision about whether and which cancer screening tests you choose.
Although we talk about cancer as if it were one disease, it is actually many different diseases. Some are common, and some are rare. In this post I’m going to write about the five most common cancers in the United States. I will focus on incidence (how common they are in the population), risk factors for these cancers, and especially risk factors that can be reduced or eliminated. I will not talk about screening for cancer. That will be the subject for another post
Breast Cancer
Breast cancer is the most common cancer in the U.S. The incidence of breast cancer in the U.S. is 128 new cases per 100,00 women per year (men get breast cancer too, but at a much lower rate). That means that one tenth of one percent of women in the U.S get breast cancer every year. The population risk increases with age. The lifetime risk of developing breast cancer is 13 per cent, or about one in eight women. The majority of that risk is in women over the age of 65. Overall, 20% of women with breast cancer eventually die from it. That means the cure rate is 80%.
Things you can do to reduce your risk of getting breast cancer
Eat a high fiber diet with lots of vegetables and avoid lots of red meat, animal fat and processed foods. Studies have shown that this kind diet reduces the risk of getting breast cancer. Of course this kind of diet also reduces the risk of heart disease and stroke as well, as I have written about in previous posts.
Be physically active. Women who are not physically active have a higher risk of getting breast cancer. There are lots of ways to be physically active. Take at least one flight of stairs instead of taking the elevator. Park as far as you can from the store when you are shopping. Take some long walks in your neighborhood if that is safe where you live. If not, drive or take the bus to a nearby park to walk.
Maintain a healthy body weight. Older women who are overweight or have obesity have a higher risk of getting breast cancer than those at a healthy weight.
Don’t take hormones (if you can help it). If you do need hormones for menopausal symptoms, take estrogen only, not estrogen and progesterone and take it for less than 5 years if possible. Some forms of hormone replacement therapy (those that include both estrogen and progesterone) taken during menopause can raise risk for breast cancer when taken for more than five years. Certain oral contraceptives (birth control pills) also have been found to raise breast cancer risk.
Reproductive decisions. Have your first pregnancy before age 30 if possible, and breast feed for as long as is practical whatever age you have children. Having a first pregnancy after age 30, not breastfeeding, and never having a full-term pregnancy can raise breast cancer risk.
Don’t drink alcohol or have no more than one drink per day. Studies show that a woman’s risk for breast cancer increases with the more alcohol she drinks.
Don’t smoke, or quit if you do: Studies show that smoking cigarettes increases women’s risk for breast cancer
Risk Factors for Breast Cancer You Can’t Change
Getting older. The risk for breast cancer increases with age. Most breast cancers are diagnosed after age 50.
Genetic mutations. Women who have inherited changes (mutations) to certain genes, such as BRCA1 and BRCA2, are at higher risk of breast and ovarian cancer.
Reproductive history. Starting menstrual periods before age 12 and starting menopause after age 55 expose women to hormones longer, raising their risk of getting breast cancer.
Having dense breasts.Dense breasts have more connective tissue than fatty tissue, which can sometimes make it hard to see tumors on a mammogram. Women with dense breasts are more likely to get breast cancer.
Personal history of breast cancer or certain non-cancerous breast diseases. Women who have had breast cancer are more likely to get breast cancer a second time. Some non-cancerous breast diseases such as atypical hyperplasia or lobular carcinoma in situ are associated with a higher risk of getting breast cancer.
Family history of breast or ovarian cancer. A woman’s risk for breast cancer is higher if she has a mother, sister, or daughter (first-degree relative) or multiple family members on either her mother’s or father’s side of the family who have had breast or ovarian cancer. Having a first-degree male relative with breast cancer also raises a woman’s risk.
Previous treatment using radiation therapy. Women who had radiation therapy to the chest or breasts (for instance, treatment of Hodgkin’s lymphoma) before age 30 have a higher risk of getting breast cancer later in life.
Exposure to the drug diethylstilbestrol (DES). DES was given to some pregnant women in the United States between 1940 and 1971 to prevent miscarriage. Women who took DES, or whose mothers took DES while pregnant with them, have a higher risk of getting breast cancer.
Hormonal changes from night shift work: Some studies have shown that night shift work may increase the risk of breast cancer.
There is no point in worrying about things you can’t change, but if you are at increased risk for breast cancer from one or more of these risk factors, that might affect your decisions about whether and when to get screening mammograms. More about screening in another post.
Prostate Cancer
Prostate cancer is the second most common cancer in the U.S. It is the most common cancer in men. The incidence of prostate cancer in the U.S. is 113 per 100,00 men per year. That means, like breast cancer for women, about one tenth of one per cent of men will be diagnosed with prostate cancer every year. Like breast cancer, the population risk increases with age. The lifetime risk of developing prostate cancer for a male is 13 per cent or about 1 in 8. That is about the same lifetime risk risk for women for breast cancer. Overall 3.2% of men will eventually die from prostate cancer. That is a cure rate of 96.2%, much higher than for breast cancer. Part of the reason for the low death rate is that many prostate cancers grow so slowly that more men die with prostate cancer than from prostate cancer.
Risk Factors for Prostate Cancer
Things you can do to reduce your population risk of getting prostate cancer
Diet: Once again, a diet low in animal fat, high in unprocessed and high fiber foods, especially cruciferous vegetables like broccoli and cauliflower seem to be especially protective. Tomato based products, which are high in lycopene also seem to reduce population risk of prostate cancer. Soy intake as well as drinking coffee also seems to be protective.
Alcohol. Alcohol intake does not seem to be a a risk factor for prostate cancer. It is a risk factor for some other cancers that I will write about later.
Don’t smoke cigarettes (or marijuana). Smoking both cigarettes and marijuana increase the risk of prostate cancer
Maintain a normal body weight. Like for breast cancer, obesity increases the risk for prostate cancer.
Exercise. While exercise is good for you in lots of ways, it does not seem to decrease the population risk for prostate cancer.
Risk Factors for prostate cancer you can’t change
Age. Prostate cancer rarely occurs before the age of 40, but peaks between age 65 and 74. Autopsy studies have shown that low grade prostate cancer, never diagnosed during life, is extremely common as age increases. In men 71-80 it can be up to 73%! These low grade prostate cancers never caused any symptoms and the men in the autopsy studies died from something else.
Heredity. If family members have had prostate cancer, especially first degree relatives (father, grandfather) your population risk for prostate cancer is substantially increased
Race. Black men are more likely to get prostate cancer and also more aggressive prostate cancer.
Chemical exposure. Exposure to certain chemicals, especially the herbicide agent orange increase the population risk of prostate cancer.
Once again, there is no point in worrying about things you can’t change. Screening for prostate cancer is very controversial. More about that in another post.
Lung Cancer
Lung cancer is the third most common cancer in the U.S. The incidence of lung cancer is 52 per 100,000 per year, which translates to five one hundredths of 1 per cent of the U.S. population per year that will be diagnosed with lung cancer. The lifetime risk of lung cancer is about 6% of people in the U.S. Of those diagnosed with lung cancer, only 23% will live 5 years after diagnosis. That is a much lower cure rate than for breast cancer and prostate cancer.
Smoking. Smoking cigarettes or cigars or smoking a pipe are the biggest risk factor for lung cancer. People who quit smoking before age 40 have a 90% reduction in smoking related diseases including lung cancer. People who quit smoking by age 54 reduce their risk by two thirds. The risk of lung cancer is still somewhat increased for former smokers as compared to never smokers even 30 years after quitting smoking.
Second Hand Smoke. Breathing other smoker’s smoke also increases your risk of getting lung cancer by 20-30%.
Radon. Radon is the second leading cause of lung cancer after smoking. Radon is a naturally occurring gas that forms in rocks, soil, and water. It cannot be seen, tasted, or smelled. It can accumulate in buildings, especially basements. Homes can be tested for Radon and a simple ventilation fan can decrease radon to safe levels. If your house has not been tested for Radon, it should be. You can buy Radon test kits at a hardware store or on Amazon.
Asbestos Exposure. People who have been exposed to asbestos have an increased risk of lung cancer. Asbestos used to be used as insulation in buildings, but has been banned for years. Asbestos is still in some homes. It is of no risk to residents of those homes as long as it is not disturbed. The risk comes when houses that contain asbestos are torn down or re-modeled.
Other Workplace Exposures.
Other carcinogens (cancer-causing agents) found in some workplaces that can increase lung cancer risk include:
Radioactive ores such as uranium
Inhaled chemicals such as arsenic, beryllium, cadmium, silica, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas, and chloromethyl ethers
People who have had radiation therapy to the chest for other cancers are at higher risk for lung cancer, particularly if they smoke. Examples include people who have been treated for Hodgkin disease or women who get chest radiation after a mastectomy for breast cancer. Women who have radiation therapy to the breast after a lumpectomy do not appear to have a higher than expected risk of lung cancer.
Air pollution: in cities, air pollution (especially near heavily trafficked roads) appears to raise the risk of lung cancer slightly. This risk is far less than the risk caused by smoking, but some researchers estimate that worldwide about 5% of all deaths from lung cancer may be due to outdoor air pollution.
Personal or family history of lung cancer
If you have had lung cancer, you have a higher risk of developing another lung cancer.
Brothers, sisters, and children of people who have had lung cancer may have a slightly higher risk of lung cancer themselves, especially if the relative was diagnosed at a younger age. It’s not clear how much of this risk might be due to shared genes among family members and how much might be from shared household exposures (such as tobacco smoke or radon).
Researchers have found that genetics seems to play a role in some families with a strong history of lung cancer.
Once again, there is no point in worrying about risk factors you cannot change. There is a screening test for lung cancer for people who are current or former smokers. More about that in another post.
Colorectal Cancer
Colorectal cancer is the fourth most common cancer in the U.S. The incidence of colorectal cancer is about 38 per 100,000 people per year in the U.S. This means that 4 one hundredths of one per cent of people in the U.S. get colorectal cancer every year. The lifetime risk of getting colorectal cancer is about 4% of people in the U.S. Overall, 35% of people who have colorectal cancer eventually die from it giving an overall cure rate of 65%. The risk of death from colorectal cancer is very dependent on the stage of cancer when it is diagnosed. If colorectal cancer is diagnosed when it is localized, the cure rate is 91%. If it is diagnosed when it has already spread to other parts of the body, the cure rate is 15%.
These are exactly the same modifiable risk factors for breast cancer and prostate cancer. Improving diet, maintaining a normal weight, limiting or eliminating alcohol consumption, and not smoking or quitting smoking decreases population risk of three different cancers.
Risk Factors you cannot change
Age. Almost all colorectal cancers occur after the age of 45 and the vast majority of these occur over the age of 50..
Because chance of cure of colorectal cancer is so much greater when diagnosed at an early stage, screening for colorectal cancer can make a big difference. More about this in another post.
Melanoma Skin Cancer
Melanoma of the skin is the 5th most common cancer in the U.S. It is necessary to specify melanoma of the skin, because melanoma can also occur in the retina of the eye or in any other organ that contains melanocytes (pigment cells). These non-skin melanomas are fortunately rare. The incidence of melanoma of the skin is about 23 per 100,000 people per year or 2 one hundredths of 1 per cent per year. Of those people who develop melanoma of the skin, 6.3% eventually die from it, giving a cure rate of 93.7%. The lifetime risk of getting melanoma is about 2 per cent of people in the U.S.
What do skin melanomas look like?
Warning Signs
a new spot on the skin or a spot that is changing in size, shape, or color.
a spot that looks different from all of the other spots on your skin (known as the ugly duckling sign).
The ABCDE rule.
A is for Asymmetry: One half of a mole or birthmark does not match the other.
B is for Border:The edges are irregular, ragged, notched, or blurred.
C is for Color:The color is not the same all over and may include different shades of brown or black, or sometimes with patches of pink, red, white, or blue.
D is for Diameter:The spot is larger than 6 millimeters across (about ¼ inch – the size of a pencil eraser), although melanomas can sometimes be smaller than this.
E is for Evolving: The mole is changing in size, shape, or color.
Exposure to ultraviolet (UV) rays is a major risk factor for most melanomas. Sunlight is the main source of UV rays. Tanning beds and sun lamps are also sources of UV rays.While UV rays make up only a very small portion of the sun’s rays, they are the main cause of the damaging effects of the sun on the skin. UV rays damage the DNA (genes) inside skin cells. Skin cancers can begin when this damage affects the DNA of genes that control skin cell growth.
The pattern and timing of the UV exposure may play a role in melanoma development. For example, melanoma on the trunk (chest and back) and legs has been linked to frequent sunburns (especially in childhood). This might also have something to do with the fact that these areas aren’t constantly exposed to UV light. Some evidence suggests that melanomas that start in these areas are different from those that start on the face, neck, and arms, where the sun exposure is more constant.
Sunscreen
High protection value sunscreens do prevent sunburn, but paradoxically, people who use high protection sunscreens have an increased risk of skin melanoma. Does that mean sunscreens cause melanoma? No, it means that people who use high protective value sunscreens and apply them frequently are more likely to purposely spend time in the sun (sun bathing). The increased ultraviolet exposure overwhelms the protective value of the sun screen. Avoiding sun bathing and using high protective sun screen when you are working outdoors, as well as wearing a hat and protective clothing is the best way to reduce your population risk of skin melanoma (as well as other types of skin cancers.
Be Vigilant
Be aware of the warning signs above. If you have a mole or a skin lesion that meets any of the warning sign criteria, it is worth a trip to the doctor to check it out.
Risk Factors you can’t do anything about
Moles
A mole (also known as a nevus) is a benign (non-cancerous) pigmented tumor. Babies are not usually born with moles; they often begin to appear in children and young adults.
Having many moles: Most moles will never cause any problems, but someone who has many moles is more likely to develop melanoma.
Atypical moles (dysplastic nevi): These moles look a little like normal moles but also have some features of melanoma. They are often larger than other moles and have an abnormal shape or color. (See Signs and Symptoms of Melanoma Skin Cancer for descriptions of how moles and melanomas look.) They can appear on skin that is exposed to the sun as well as skin that is usually covered, such as on the buttocks or scalp. Dysplastic nevi often run in families. A small percentage of dysplastic nevi may develop into melanomas. But most dysplastic nevi never become cancer, and many melanomas seem to arise without a pre-existing dysplastic nevus.
Dysplastic nevus syndrome (atypical mole syndrome): People with this inherited condition have many dysplastic nevi. If at least one close relative has had melanoma, this condition is referred to as familial atypical multiple mole and melanoma syndrome, or FAMMM. People with this condition have a very high lifetime risk of melanoma, so they need to have very thorough, regular skin exams by a dermatologist (a doctor who specializes in skin problems). Sometimes full body photos are taken to help the doctor recognize if moles are changing and growing. Many doctors recommend that these patients be taught to do monthly skin self-exams as well.
Congenital melanocytic nevi: Moles present at birth are called congenital melanocytic nevi. The lifetime risk of melanoma developing in congenital melanocytic nevi is estimated to be between 0 and 5%, depending on the size of the nevus. People with very large congenital nevi have a higher risk, while the risk is lower for those with small nevi. For example, the risk for melanoma is very low in congenital nevi smaller than the palm of the hand, while those that cover large portions of back and buttocks (“bathing trunk nevi”) have significantly higher risks
Lots of irregular or large moles. The chance of any single mole turning into cancer is very low. However, anyone with lots of irregular or large moles has an increased risk for melanoma.
Fair skin, freckling, and light hair
The risk of melanoma is much higher for whites than for African Americans. Whites with red or blond hair, blue or green eyes, or fair skin that freckles or burns easily are at increased risk.
Family history of melanoma
Your risk of melanoma is higher if one or more of your first-degree relatives (parents, brothers, sisters, or children) has had melanoma. Around 10% of all people with melanoma have a family history of the disease.
Personal history of melanoma or other skin cancers
A person who has already had melanoma has a higher risk of getting melanoma again. People who have had basal or squamous cell skin cancers are also at increased risk of getting melanoma.
Having a weakened immune system
A person’s immune system helps fight cancers of the skin and other organs. People with weakened immune systems (from certain diseases or medical treatments) are more likely to develop many types of skin cancer, including melanoma.
Being older
Melanoma is more likely to occur in older people, but it is also found in younger people. In fact, melanoma is one of the most common cancers in people younger than 30 (especially younger women). Melanoma that runs in families may occur at a younger age.
Being male
In the United States, men have a higher rate of melanoma than women, although this varies by age. Before age 50, the risk is higher for women; after age 50 the risk is higher in men.
Xeroderma pigmentosum
Xeroderma pigmentosum (XP) is a rare, inherited condition that affects skin cells’ ability to repair damage to their DNA. People with XP have a high risk of developing melanoma and other skin cancers when they are young, especially on sun-exposed areas of their skin.
Bottom Line
These five cancers account for half of the cancer diagnoses made every year in the U.S. There are other less common types of cancer, only a few of which have screening tests to detect them early. I will write about some of those cancers in my coming post on screening for cancer. While everyone worries about cancer, the majority of people in the U.S. will never get cancer. The lifetime overall population risk for a U.S.male of getting any kind of cancer other than skin cancer is 40%. For women, that lifetime risk is 39%. These risks average together people at high risk and people at low risk. Your population risk could be substantially lower (or higher) than this average risk.
