Clinicians are taught that colorectal cancer is a disease of the aging population, with the average age of diagnosis in the United States being 72 years.1 Although most patients with colorectal cancer are diagnosed later in life, the incidence and mortality for those over age 50 years have been falling at the same time that these rates have been steadily rising for younger adults. This alarming trend was brought into the spotlight with a recent New York Times article that discussed the most recent statistics provided by the American Cancer Society (ACS).2,3 Since 2000, the incidence of colorectal cancer increased 22% among adults under age 50.3 This is in stark contrast with the 32% reduction in incidence for adults over age 50 years, attributable to enhanced screening leading to identification and removal of precancerous polyps.3,4 When comparing people born in 1950 with those born in 1990, those born in 1990 have double the risk of developing colon cancer and quadruple the risk of developing rectal cancer.5 Even more alarming, researchers have estimated that by 2030, more than 1 in 10 diagnoses of colon cancer and nearly 1 in 4 diagnoses of rectal cancer will be in people under age 50 years.4
In addition to the increased incidence, younger patients often are diagnosed with more advanced disease. The New York Times article described three young patients who had symptoms for a prolonged period of time before being diagnosed with colorectal cancer.2 Unfortunately, their diagnoses were delayed because either the patient postponed seeking medical care or clinicians did not consider colorectal cancer as part of the differential diagnosis. Researchers found that among patients with colorectal cancer who were under age 50 years, the incidence of those diagnosed with metastatic disease increased 3% annually compared with only a 1% annual increase in localized disease since 2000.3 Delays in diagnosis often result in increased morbidity and mortality because the disease was more advanced at the time of diagnosis.
The cause for this paradoxical rise in colorectal cancer is subject to speculation. Well-known risk factors include familial and genetic causes. Patients with a family history of colon cancer or an inherited syndrome are at a much higher risk than the average population. The same is true for patients with hereditary syndromes such as Lynch syndrome.6 However, only 20% of all cases of colorectal cancer occur in the context of family history and only 2% to 4% of all colorectal cancers are found in patients with hereditary syndromes.6 Because most patients with the disease have no known familial or genetic cause, these causes are unlikely to be the reason for the increase in risk for young patients.
An alternative explanation is poor lifestyle choices. Studies have shown that obesity, a diet high in red meat and processed foods, tobacco and alcohol abuse, and a sedentary lifestyle increase the risk of developing colorectal cancer. Therefore, lifestyle changes over the past decades may be a major contributor to this increasing rate of colorectal cancer in younger adults.4 However, at this time, more studies are needed to further understand the underlying causes of the shift in demographics for those afflicted by the disease.
Until more answers are found, early detection is key to reducing mortality. Clinicians should keep a high index of suspicion for colorectal cancer when patients of any age report symptoms such as melena, hematochezia, alterations in bowel habits, abdominal and/or pelvic pain, fatigue, or unexplained weight loss, or when patients are found to be anemic.7 Patients also should be educated on the importance of early reporting of such symptoms.
In addition to evaluating patients with symptoms suggestive of colorectal cancer, clinicians should screen patients under age 50 years with known risk factors. Given the elevated risk in patients with a family history of colorectal cancer, those with a first-degree family member diagnosed with colorectal cancer should undergo screening colonoscopy beginning at age 40 years or 10 years before the earliest age of diagnosis.6 Patients with a personal or family history of a hereditary syndrome, such as Lynch syndrome, or with inflammatory bowel disease are at particularly high risk and require close monitoring, typically by a gastroenterologist, and early screening based on established guidelines.6
For the general population under age 50 years, clinicians should educate patients of the risk of colorectal cancer while stressing the importance of a healthful lifestyle. Counseling should include the importance of maintaining a healthful weight, following a healthful diet, exercising regularly, limiting alcohol use, and avoiding cigarette smoking as primary prevention strategies for colorectal cancer.
We eagerly await more studies to better inform clinicians about prevention and appropriate screening for patients at risk for colorectal cancer. For now, clinicians must remember that any adult may develop colorectal cancer and all patients with symptoms must be appropriately evaluated.
Remember that early diagnosis can save a life!
2. Rabin R. Sharp rise in cancer of colon and rectum in young people. The New York Times
. March 1, 2017:A20.
3. Siegel RL, Miller KD, Fedewa SA, et al Colorectal cancer statistics, 2017. CA Cancer J Clin
4. Bailey CE, Hu CY, You YN, et al Increasing disparities in the age-related incidences of colon and rectal cancers in the United States, 1975-2010. JAMA Surg
5. Siegel RL, Fedewa SA, Anderson WF, et al Colorectal cancer incidence patterns in the United States, 1974-2013. J Natl Cancer Inst
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7. Ahnen DJ, Wade SW, Jones WF, et al The increasing incidence of young-onset colorectal cancer: a call to action. Mayo Clin Proc