The New Reality of Colorectal Cancer

Once considered a disease that primarily affected elderly people, colorectal cancer is now affecting younger generations.1 In 2018, the American Cancer Society updated its guidelines for colorectal cancer screening, urging people to begin routine colonoscopies at a younger age.2 

Colorectal cancer, or cancer of either the colon or rectum, is the fourth most common cancer and the second leading cause of cancer-related deaths in the United States, affecting one in every 20 people every year. In 2019, 145,600 Americans were diagnosed with colorectal cancer and approximately 51,020 related deaths were reported. In 2020, the American Cancer Society predicts 147,950 new developments of and 53,200 related deaths from colorectal cancer. This includes 17,930 cases and 3,640 related deaths in patients younger than 50.3

How Colorectal Cancer Begins

Development. There are two types of polyps (i.e., growths) that can form in the colon or rectum: adenomatous polyps, also called adenomas, and hyperplastic polyps, which are the more common type. Adenomas typically become cancerous, while hyperplastic polyps are usually not considered precancerous. Polyps larger than 1cm and the presence of more than one polyp can indicate an increased risk of these growths becoming cancerous.4 In addition, the occurrence of dysplasia, a precancerous condition characterized by the presence of abnormal cells after the polyp is removed, is also a predictor of future colorectal cancer.5 

If not treated, the cancer cells in the polyp(s) can penetrate deeper layers of the colon walls or spread throughout the colon, potentially affecting other areas of the digestive track. 96 percent of colorectal cancer cases are composed of cancer cells known as adenocarcinomas, which grow in the mucus of the colon and rectum. Rarer types of colorectal cancers include carcinoid tumors that affect the hormone-making cells in the colon, gastrointestinal stromal tumors (GISTs) that form in special cells located in the colon wall, non-Hodgkin’s lymphoma beginning in the colon, and sarcomas, which form within the blood vessels and connective tissue of the colon and rectum.4,5

Symptoms. Symptoms depend on the type, location, and stage of the cancer. During the early stages of colorectal cancer, symptoms tend to be either minor or non-existent, but early warning signs might include sudden weight loss, narrow, ribbon-like stool, rectal bleeding, anemia, persistent abdominal pain, and the urge to have a bowl movement but nothing passes, also called tenesmus. Constipation, diarrhea, changes in bowel habits, abdominal bloating and cramps, loss of appetite, nausea, vomiting, jaundice, weakness, and fatigue indicate cancer progression.6

Prevention and Treatment

Colonoscopies are one of many procedures that can treat and prevent the development of colorectal cancers. Polyps can be detected and removed during a colonoscopy.7 Along with colonoscopies, fecal occult blood tests, deoxyribonucleic acid (DNA) stool tests, and sigmoidoscopies are methods used to detect traces of colorectal cancer. Whichever method is used, routine screenings are essential for people aged 45 years or older. These routine screenings allow healthcare providers to identify and monitor cancer cells before the patient begins to experience symptoms. According to the National Cancer Institute, 60 percent of colorectal cancer cases could be prevented through routine cancer screenings. Currently, one in three people are not up to date on their screenings.4,5,7

Increasing rates of colorectal cancer in younger people have affected current recommendations for screening and prevention. The number of deaths from colorectal cancer are declining by about 2.4 percent each year due to early detection and treatment; however, colorectal cancer is becoming increasingly more common in people younger than 50. Three out of four people who are diagnosed with colorectal cancer begin to show symptoms in their forties.8,9

This increase prompted the American Cancer Society to release new guidelines in 2018 that urged people of average risk to schedule their first colonoscopy at the age of 45. Prior to 2018, it was recommended that average-risk individuals get their first colonoscopy at age 50; a colonoscopy at 45 was only recommended if the person was at an increased risk for colorectal cancer as a result of factors summarized in Table 1.1–4,8,9

TABLE 1. Risk of Colorectal Cancer, according to the American Cancer Society


Contributing Factors


Being at least 45 years of age. 


A personal history of colorectal cancer.

A family history of inflammatory bowel disease, colorectal cancer and/or colon polyps. 

Familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary non-polyposis colon cancer or HNPCC). 



Heavy drinking

Poor dietary habits

Environmental and Genetic Factors

A family history of colorectal cancer plays a small role in the development of the disease. However, only 20 percent of colorectal cancer cases are due to a genetic predisposition.10,12

Environmental factors, primarily dietary choices, are far more influential than genetics. The biggest culprit for the development of colorectal cancer in younger people is unhealthy dietary habits throughout childhood and most of adulthood.10–12

A diet high in saturated fat found in dairy, cheese, and eggs, and animal protein, especially red and processed meat (i.e., meat that has been salted, cured, fermented, or smoked to enhance preservation) restructures the gut microbiome to hinder colorectal protection. Protein fermentation and bile acid deconjugation caused by the consumption of animal products and saturated fat causes pro-inflammatory reactions and abnormal tissue growth that damage colonic cells, turn bile acids into carcinogens, and significantly heighten the risk of colorectal cancer.13,14–16 

Along with diet, obesity, inactivity, smoking, and drinking are other lifestyle factors that are linked to colorectal cancer.17 

Reduce Your Risk with Diet and Exercise

Eat more fiber. Increased fiber intake can reduce the rate of reoccurring colon polyps and contributes to an overall reduced incidence of colon cancer. Fiber stimulates the production of short-chain fatty acids in the gut, which can inhibit irregular tissue growth, reduce inflammation, and protect the colon. Insoluble fiber found in whole grains, fruits, vegetables, and beans maintains regularity and movement of the digestive tract. This is particularly beneficial for those who suffer from constipation, as irregular bowel movements allow prolonged contact between carcinogens in the stools and the gut wall.18 Sources of fiber include lentils, barely, quinoa, oats, bran, brown rice, spinach, collard greens, raspberries, blackberries, blueberries, mangos, prunes, nuts, and seeds. Aim for 50 grams of fiber a day.19,20 


FAST FACT: Increased intake of blackberries have been shown to reduce rectal polyps, which can become cancerous if not removed.  SOURCE: Stoner GD. Foodstuffs for preventing cancer: the preclinical and clinical development of berries. Cancer Prev Res (Phila). 2009 Mar;2(3):187-94.


Reduce animal products. Red and processed meats are considered Group 2A carcinogens, meaning there is notable evidence to suggest they cause cancer in humans. Bacon, a processed meat, is classified as a Group 1A carcinogen, as there is enough evidence to confirm it causes cancer in humans.21,22 Other animal products, such as milk, cheese, eggs, and even fish naturally harbor carcinogens that put people at a greater risk for colorectal cancer.23

A recent study showed that plant-based diet changes suppressed cancer growth and 20 to 30 percent more malignant cells were killed compared to a “regular” diet that included animal products.24 The authors of this study reasoned that animal products typically stimulate the production of IGF-1, a hormone responsible for cell growth and an increased risk for cancer if overproduced.24 

If you’re a meat or cheese lover, the idea of reducing intake of some of your favorite foods can seem understandably daunting, but a gradual transition can make the process easier and more enjoyable. Mix smaller servings of meat with vegetables and whole grains and gradually reduce the amount of meat over time. There are mild opiate-like composites in cheese that latch onto the same receptors in the brain as addictive substances, leading to mild withdrawal effects in the initial period after reducing cheese consumption.25 Awareness of these effects and experimenting with plant-based dairy alternatives can make this initial period more pleasant and even fun as you learn new ways to create your favorite dishes with the abundance of cheese alternatives on the market today. 

Exercise. It’s no secret that exercise is a vital component of maintaining many aspects of physical health, and research indicates that this rings true for preventing colorectal cancer. Daily physical activity alone has been shown to prevent the development of colon cancer by 15 percent. Patients with advanced stages of colorectal cancer can delay the progression of the cancer and improve chemotherapy treatment symptoms with physical activity as well.26

Get regular colorectal cancer screenings. As always, your physician is your best resource for examining your risk of colorectal cancer and creating a screening plan that is best suited to you. Discuss your family history, lifestyle, and eating habits with your healthcare physician. Learn your level of risk, familiarize yourself with the symptoms of colon cancer, and get screened for colorectal cancer when at the commensurate age or when recommended by your doctor.7


  1. Ng O, Watts E, Bull CA, Morris R, et al. Colorectal cancer outcomes in patients aged over 85 years. Ann R Coll Surg Engl. 2016;98(3):216–221. 
  2. The American Cancer Society site. American Cancer Society Updates Colorectal Cancer Screening Guideline. 30 May 2018. Accessed 28 Apr 2020. 
  3. Siegel R, Miller K, Sauer A, et al. Colorectal cancer statistics. ACS Journals. 2020; 70 (1):3–30. 
  4. Centers for Disease Control and Prevention site. Basic information about colorectal cancer. Updated 10 Feb 2020. Accessed 5 Apr 2020.  
  5. The American Cancer Society site. What is colorectal cancer? Updated 18 Feb 2018. Accessed 5 Apr 2020. 
  6. Cancer Treatment Centers of America site. Colorectal cancer symptoms. Accessed 5 Apr 2020. 
  7. National Cancer Institute site. Colorectal Cancer Screening (PDQ®)–Patient Version. Updated 15 Mar 2019. Accessed 5 Apr 2020. 
  8. Murff H. Fight Colorectal Cancer site. The under 50 phenomenon. Accessed 5 Apr 2020.
  9. Fight Colorectal Cancer site. Facts and stats. Accessed 5 Apr 2020. 
  10. Fight Colorectal Cancer site. Colorectal cancer in young adults. Accessed 5 Apr 2020. 
  11. The American Cancer Society site. Colorectal cancer risk factors. Updated 21 Feb 2018. Accessed 5 Apr 2020. 
  12. Ballester V, Rashtak S, and Boardman L. Clinical and molecular features of young-onset colo-rectal cancer. World J Gastroenterol. 2016 Feb 7;22(5):1736-44. 
  13. Ryan-Harshman M and Aldoori W. Diet and colorectal cancer: Review of the evidence. Can Fam Physician. 2007;53(11):1913–1920. 
  14. Yang J, Yu J. The association of diet, gut microbiota and colorectal cancer: what we eat may imply what we get. Protein Cell. 2018;9(5):474–487.
  15. Gagnière J, Raisch J, Veziant J, et al. Gut microbiota imbalance and colorectal cancer. World J Gastroenterol. 2016 Jan 14;22(2):501–518. 
  16. Bultman SJ. Interplay between diet, gut microbiota, epigenetic events, and colorectal cancer. Mol Nutr Food Res. 2017 Jan;61(1). 
  17. Tárraga López PJ, Albero JS, and Rodríguez-Montes JA. Primary and secondary prevention of colorectal cancer. Clin Med Insights Gastroenterol. 2014 Jul 14;7:33-46. 
  18. Kojima M, Wakai K, Tokudome S, et al. Bowel movement frequency and risk of colorectal cancer in a large cohort study of Japanese men and women. Br J Cancer. 2004;90(7):1397–1401.
  19. Harvard Health Publishing site. Surprising Sources of Dietary Fiber. Dec 2017. Accessed 28 Apr 2020. 
  20. Ocvirk S, Wilson AS, Appolonia CN, et al. Fiber, fat, and colorectal cancer: new insight into modifiable dietary risk factors. Curr Gastroenterol Rep. 2019 Dec 2;21(11):62.
  21. Scientific Committees site. Standard IARC classification. Accessed 5 Apr 2020. 
  22. The American Cancer Society site. World Health Organization says processed meat causes cancer. 26 Oct 2015. Accessed 28 Apr 2020. 
  23. National Research Council. Carcinogens and Anticarcinogens in the Human Diet: A Comparison of Naturally Occurring and Synthetic Substances. Washington, DC: The National Academies Press; 1996.
  24. Madigan M, Karhu E. The role of plant-based nutrition in cancer prevention. J Unexplored Med Data. 2018;3:9. 
  25. Physician’s Committee for Responsible Medicine site. Five Frightful Facts About Cheese. Oct 28, 2016. Accessed 28 Apr 2020. 
  26. Guercio BJ, Zhang S, Ou FS, et al. Associations of physical activity with survival and progression in metastatic colorectal cancer: results from Cancer and Leukemia Group B (Alliance). J Clin Oncol. 2019;37(29) 2620–2631. 

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