PDFs by language
Our 24/7 cancer helpline provides support for people dealing with cancer. We can connect you with trained cancer information specialists who will answer questions about a cancer diagnosis and provide guidance and a compassionate ear.
Chat live online
Select the Live Chat button at the bottom of the page
At our National Cancer Information Center trained Cancer Information Specialists can answer questions 24 hours a day, every day of the year to empower you with accurate, up-to-date information to help you make educated health decisions. We connect patients, caregivers, and family members with valuable services and resources.
Or ask us how you can get involved and support the fight against cancer. Some of the topics we can assist with include:
For medical questions, we encourage you to review our information with your doctor.
A risk factor is anything that raises your chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t be changed.
But having a risk factor, or even many, does not mean that you will get the disease. And some people who get the disease may not have any known risk factors.
Researchers have found several risk factors that might increase a person’s chance of developing colorectal polyps or colorectal cancer.
Many lifestyle-related factors have been linked to colorectal cancer. In fact, more than half of all colorectal cancers are linked to risk factors that can be changed.
If you are overweight or obese (very overweight), your risk of developing and dying from colorectal cancer is higher. Being overweight raises the risk of colon and rectal cancer in people, but the link seems to be stronger in men. Getting to and staying at a healthy weight may help lower your risk.
If you're not physically active, you have a greater chance of developing colon cancer. Regular moderate to vigorous physical activity can help lower your risk.
A diet that's high in red meats (such as beef, pork, lamb, or liver) and processed meats (like hot dogs and some luncheon meats) raises your colorectal cancer risk.
Cooking meats at very high temperatures (frying, broiling, or grilling) creates chemicals that might raise your cancer risk. It’s not clear how much this might increase your colorectal cancer risk.
Having a low blood level of vitamin D may also increase your risk.
Following a healthy eating pattern that includes plenty of fruits, vegetables, and whole grains, and that limits or avoids red and processed meats and sugary drinks probably lowers risk.
People who have smoked tobacco for a long time are more likely than people who don't smoke to develop and die from colorectal cancer. Smoking is a well-known cause of lung cancer, but it's linked to a lot of other cancers, too. If you smoke and want to know more about quitting, see our Guide to Quitting Smoking.
Colorectal cancer has been linked to moderate to heavy alcohol use. Even light-to-moderate alcohol intake has been associated with some risk. It is best not to drink alcohol. If people do drink alcohol, they should have no more than 2 drinks a day for men and 1 drink a day for women. This could have many health benefits, including a lower risk of many kinds of cancer.
Your risk of colorectal cancer goes up as you age. Younger adults can get it, but it's much more common after age 50. Colorectal cancer is rising among people who are younger than age 50 and the reason for this remains unclear.
If you have a history of adenomatous polyps (adenomas), you are at increased risk of developing colorectal cancer. This is especially true if the polyps are large, if there are many of them, or if any of them show dysplasia.
If you've had colorectal cancer, even though it was completely removed, you are more likely to develop new cancers in other parts of the colon and rectum. The chances of this happening are greater if you had your first colorectal cancer when you were younger.
If you have inflammatory bowel disease (IBD), including either ulcerative colitis or Crohn’s disease, your risk of colorectal cancer is increased.
IBD is a condition in which the colon is inflamed over a long period of time. People who have had IBD for many years, especially if untreated, often develop dysplasia. Dysplasia is a term used to describe cells in the lining of the colon or rectum that look abnormal, but are not cancer cells. They can change into cancer over time.
If you have IBD, you may need to start getting screened for colorectal cancer when you are younger and be screened more often.
Inflammatory bowel disease is different from irritable bowel syndrome (IBS), which does not appear to increase your risk for colorectal cancer.
Most colorectal cancers are found in people without a family history of colorectal cancer. Still, as many as 1 in 3 people who develop colorectal cancer have other family members who have had it.
People with a history of colorectal cancer in a first-degree relative (parent, sibling, or child) are at increased risk. The risk is even higher if that relative was diagnosed with cancer when they were younger than 50, or if more than one first-degree relative is affected.
The reasons for the increased risk are not clear in all cases. Cancers can “run in the family” because of inherited genes, shared environmental factors, or some combination of these.
Having family members who have had adenomatous polyps is also linked to a higher risk of colon cancer. (Adenomatous polyps are the kind of polyps that can become cancer.)
If you have a family history of adenomatous polyps or colorectal cancer, talk with your doctor about the possible need to start screening before age 45. If you've had adenomatous polyps or colorectal cancer, it’s important to tell your close relatives so that they can pass along that information to their doctors and start screening at the right age.
About 5% of people who develop colorectal cancer have inherited gene changes (mutations) that cause family cancer syndromes and can lead to them getting the disease.
The most common inherited syndromes linked with colorectal cancers are Lynch syndrome (hereditary non-polyposis colorectal cancer, or HNPCC) and familial adenomatous polyposis (FAP), but other rarer syndromes can increase colorectal cancer risk, too.
Lynch syndrome is the most common hereditary colorectal cancer syndrome. It accounts for about 2% to 4% of all colorectal cancers. In most cases, this disorder is caused by an inherited defect in either the MLH1, MSH2 or MSH6 gene, but changes in other genes can also cause Lynch syndrome. These genes normally help repair DNA that has been damaged.
The cancers linked to this syndrome tend to develop when people are relatively young. People with Lynch syndrome can have polyps, but they tend to only have a few. The lifetime risk of colorectal cancer in people with this condition may be as high as 50%, but this depends on which gene is affected.
Women with this condition also have a very high risk of developing cancer of the endometrium (lining of the uterus). Other cancers linked with Lynch syndrome include cancer of the ovary, stomach, small intestine, pancreas, kidney, prostate, breast, ureters (tubes that carry urine from the kidneys to the bladder), and bile duct. People with Turcot syndrome (a rare inherited condition) who have a defect in one of the Lynch syndrome genes are at a higher risk of colorectal cancer as well as a specific type of brain cancer called glioblastoma.
For more on Lynch syndrome, see What Causes Colorectal Cancer?, Can Colorectal Cancer Be Prevented?, and Family Cancer Syndromes.
FAP is caused by changes (mutations) in the APC gene that a person inherits from parents. About 1% of all colorectal cancers are caused by FAP.
In the most common type of FAP, hundreds or thousands of polyps develop in a person’s colon and rectum, often starting at ages 10 to 12 years. Cancer usually develops in 1 or more of these polyps as early as age 20. By age 40, almost all people with FAP will have colon cancer if their colon hasn’t been removed to prevent it. People with FAP also have an increased risk for cancers of the stomach, small intestines, pancreas, liver, and some other organs.
There are 3 sub-types of FAP:
Since many of these syndromes are linked to colorectal cancer at a young age and also linked to other types of cancer, identifying families with these inherited syndromes is important. It lets doctors recommend specific steps such as screening and other preventive measures when the person is younger. Information on risk assessment, and genetic counseling and testing for these syndromes can be found in Genetic Testing, Screening, and Prevention for People with a Strong Family History of Colorectal Cancer.
American Indian and Alaska Native people have the highest rates of colorectal cancer in the US, followed by African American men and women.
Jews of Eastern European descent (Ashkenazi Jews) have one of the highest colorectal cancer risks of any ethnic group in the world.
People with type 2 (usually non-insulin dependent) diabetes have an increased risk of colorectal cancer. Both type 2 diabetes and colorectal cancer share some of the same risk factors (such as being overweight and physical inactivity). But even after taking these factors into account, people with type 2 diabetes still have an increased risk. They also tend to have a less favorable prognosis (outlook) after diagnosis.
Some studies suggest working a night shift regularly might raise the risk of rectal cancer. This might be due to changes in levels of melatonin, a hormone that responds to changes in light. More research is needed.
Some studies have found that men who survive testicular cancer seem to have a higher rate of colorectal cancer and some other cancers. This might be because of the treatments they have received, such as radiation therapy.
Several studies have suggested that men who had radiation therapy to treat prostate cancer might have a higher risk of rectal cancer because the rectum receives some radiation during treatment. Most of these studies are based on men treated in the 1980s and 1990s, when radiation treatments were less precise than they are today. The effect of more modern radiation methods on rectal cancer risk is not clear, but research continues to be done in this area.
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
American Cancer Society. Cancer Facts & Figures 2023. Atlanta, Ga: American Cancer Society; 2023.
American Cancer Society. Colorectal Cancer Facts & Figures 2020-2022. Atlanta, Ga: American Cancer Society; 2020.
Ballester V, Rashtak S, Boardman L. Clinical and molecular features of young-onset colorectal cancer. World J Gastroenterol. 2016; 22(5):1736-1744.
Berger AH and Pandolfi PP. Ch 5 - Cancer Susceptibility Syndromes. In: DeVita VT, Hellman S, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 11th ed. Philadelphia, Pa: Lippincott-Williams & Wilkins; 2019.
Bostrom PJ, Soloway MS. Secondary cancer after radiotherapy for prostate cancer: Should we be more aware of the risk? Eur Urol. 2007;52:973-982.
Chung DC. Clinical manifestations and diagnosis of familial adenomatous polyposis. Rutgeerts P and Grover S, eds. UpToDate. Waltham, MA: UpToDate Inc. https://www.uptodate.com (Accessed on February 05, 2020.)
Dashti SG, Win AK, Hardikar SS, et al. Physical activity and the risk of colorectal cancer in Lynch syndrome. Int J Cancer. 2018;143(9):2250–2260. doi:10.1002/ijc.31611.
Grover S and Stoffel E. MUTYH-associated polyposis. Lamont JT and Robson KM, eds. UpToDate. Waltham, MA: UpToDate Inc. https://www.uptodate.com (Accessed on February 05, 2020.)
Lawler M, Johnston B, Van Schaeybroeck S, Salto-Tellez M, Wilson R, Dunlop M, and Johnston PG. Chapter 74 – Colorectal Cancer. In: Niederhuber JE, Armitage JO, Dorshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 6th ed. Philadelphia, Pa. Elsevier: 2020.
Libutti SK, Saltz LB, Willett CG, and Levine RA. Ch 62 - Cancer of the Colon. In: DeVita VT, Hellman S, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 11th ed. Philadelphia, Pa: Lippincott-Williams & Wilkins; 2019.
Lynch HT, de la Chapelle A. Hereditary colorectal cancer. N Engl J Med. 2003;348:919–932.
Macrae FA. Colorectal cancer: Epidemiology, risk factors, and protective factors. Goldberg RM and Seres D, eds. UpToDate. Waltham, MA: UpToDate Inc. https://www.uptodate.com (Accessed on February 05, 2020.)
McMaster M, Feuer EJ, Tucker MA. New Malignancies Following Cancer of the Male Genital Tract. In: Curtis RE, Freedman DM, Ron E, Ries LAG, Hacker DG, Edwards BK, Tucker MA, Fraumeni JF Jr. (eds). New Malignancies Among Cancer Survivors: SEER Cancer Registries, 1973-2000. National Cancer Institute. NIH Publ. No. 05-5302. Bethesda, MD, 2006. Accessed at http://seer.cancer.gov/archive/publications/mpmono/MPMonograph_complete.pdf on February 6, 2020.
National Cancer Institute. Physician Data Query (PDQ). Colorectal Cancer Prevention. 2019. Accessed at https://www.cancer.gov/types/colorectal/patient/colorectal-prevention-pdq on February 06, 2020.
National Center for Advancing Translational Sciences. Genetic and Rare Diseases Information Center. Turcot syndrome, 8/29/2012. Accessed at https://rarediseases.info.nih.gov/diseases/420/turcot-syndrome on February 5, 2020.
Nieder AM, Porter MP, Soloway MS. Radiation therapy for prostate cancer increases subsequent risk of bladder and rectal cancer: A population based cohort study. J Urol. 2008;180:2005-2009; discussion 2009-10.
Mazonakis M, Varveris C, Lyraraki E, Damilakis J. Radiotherapy for stage I seminoma of the testis: Organ equivalent dose to partially in-field structures and second cancer risk estimates on the basis of a mechanistic, bell-shaped, and plateau model. Med Phys. 2015;42(11):6309-6316.
National Cancer Institute. Genetics of Colorectal Cancer (PDQ®)–Health Professional Version. https://www.cancer.gov/types/colorectal/hp/colorectal-genetics-pdq#link/_2606. Accessed February 7, 2020.
Nørgaard M, Farkas DK, Pedersen L, et al. Irritable bowel syndrome and risk of colorectal cancer: a Danish nationwide cohort study. Br J Cancer. 2011;104(7):1202–1206. doi:10.1038/bjc.2011.65.
Papantoniou K, Devore EE, Massa J, et al. Rotating night shift work and colorectal cancer risk in the nurses' health studies. Int J Cancer. 2018;143(11):2709–2717. doi:10.1002/ijc.31655.
Parent ME, El-Zein M, Rousseau MC, et al. Night Work and the Risk of Cancer Among Men. Am J Epidemiol. 2012; 176(9):751-759.
Rock CL, Thomson C, Gansler T, et al. American Cancer Society guideline for diet and physical activity for cancer prevention. CA: A Cancer Journal for Clinicians. 2020;70(4). doi:10.3322/caac.21591. Accessed at https://onlinelibrary.wiley.com/doi/full/10.3322/caac.21591 on June 9, 2020.
Travis LB, Fosså SD, Schonfeld SJ, et al. Second cancers among 40,576 testicular cancer patients: focus on long-term survivors. J Natl Cancer Inst. 2005;97(18):1354-1365.
Wallis CJ, Mahar AL, Choo R, et al. Second malignancies after radiotherapy for prostate cancer: systematic review and meta-analysis. BMJ. 2016;352:i851. Published 2016 Mar 2. doi:10.1136/bmj.i851.
Win AK. Lynch syndrome (hereditary nonpolyposis colorectal cancer): Clinical manifestations and diagnosis. Lamont JT and Grover S, eds. UpToDate. Waltham, MA: UpToDate Inc. https://www.uptodate.com (Accessed on February 05, 2020.)
Zhu Z, Zhao S, Liu Y, et al. Risk of secondary rectal cancer and colon cancer after radiotherapy for prostate cancer: a meta-analysis. Int J Colorectal Dis. 2018;33(9):1149-1158. doi:10.1007/s00384-018-3114-7.
Last Revised: February 27, 2023
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.