Young Onset Colorectal Cancer

While colorectal cancer is the third most common cancer among men and women, the overall risk of the disease has been falling over the last few years. For people under the age of 50, however, cases have actually been increasing. These cases, which are considered young or early onset, have risen by about 2% per year.

Key Facts

  • Young onset colorectal cancer refers to colorectal cancers in people under 50 years old
  • These cases are becoming more frequent, more deadly, and most cases cannot be explained by inherited or hereditary syndromes
  • While the reasons for this increase are not fully understood, knowing the risks and what to watch out for can lead to timely, effective treatment


For people under the age of 50, about 40-50% of colorectal cancers are related to a definable risk factor, like an inherited colorectal cancer syndrome, chronic ulcerative colitis, or a known family history of colorectal cancer. This leaves about 50-60% of cases in the age group due to reasons that are still not fully understood.

Despite the different and uncertain causes, colorectal cancers in this age group share certain traits in common:

  • Most colorectal cancers in young people are on the left side of the colon. 
  • The most common part of the bowel affected is the rectum—the end of the digestive tract.
  • Most colorectal cancers in young people share a similar biology: they are called “microsatellite stable” or MSS. This means that, despite having mutations, these cancers have stable repair genes, which in turn means they are less likely to respond to immunotherapy treatments.

Like all colorectal cancers, early onset colorectal cancers begin as benign polyps that grow into cancer over time.


The symptoms of colorectal cancer in young people are similar to those in older age groups, and most commonly include:

  • Rectal bleeding
  • Lower abdominal cramps and pain
  • Changes in bowel habits, such as diarrhea or constipation

Anemia (a lack of healthy red blood cells) and loss of appetite, or unintentional weight loss are signs of advanced disease and should be investigated.


There are a number of ways to improve the detection and diagnosis of colorectal cancer in young people. The following measures are useful:

  • Take Symptoms Seriously: Because colorectal cancer is more typically thought of as a disease of older people, younger people and their doctors may be more likely to initially dismiss cancer as a cause for the symptoms mentioned above. This is a mistake. Rectal bleeding is never normal, and hemorrhoids may not be the cause. Patients with rectal bleeding should be checked, preferably by flexible sigmoidoscopy or even colonoscopy. Likewise, abdominal pain and/or a change in bowel movements that persist for more than a couple of days should also be checked.
  • Genetic Testing: Patients under the age of 50 who develop colorectal cancer or advanced precancerous polyps (small growths protruding from the lining of digestive tract), should be referred to genetic counselors for genetic testing. This will identify if a hereditary syndrome is present, which can not only help in guiding treatment options, but can also help others in the family discover and treat cancers earlier.
  • Screening Colonoscopy: Colonoscopies are potentially effective in preventing colon cancer, if performed at the right time. Because colorectal cancers are derived from precancerous polyps in the colon, finding them with a colonoscopy and subsequently removing them offers the opportunity to avoid the disease. Removing the polyps before they become malignant (cancerous) is the key. The average person should start having screening colonoscopies at age 45. For those with a family history of the disease, it’s strongly recommended that the person starts screening colonoscopies 10 years earlier than the family member’s age at diagnosis.


Colorectal cancer in young patients without a hereditary syndrome can be treated just like cancer in patients of any age. The primary treatment method is surgery, but chemotherapy and radiation may also play a role, depending on the stage and nature of the tumor. Immunotherapy, which can be an option for some hereditary colon cancers, is generally not useful due to the biology of the tumors.


While early onset colorectal cancer is on the rise, it still represents a minority of overall cases: only 10% of all colorectal cancers are diagnosed in people under 50. And while the death rate is increasing for that group, this is because the disease is typically discovered later for younger people, not because they get a more aggressive form. Once properly identified, the prognosis for young onset colorectal cancer is determined by tumor stage, just as it is for other age groups.

Knowing what to look out for, being aware of one’s own family history, and taking proper screening precautions are imperative in improving the outlook for younger patients facing colorectal cancer.

Next Steps

If you or a loved one is dealing with young onset colorectal cancer, we’re here to help. Our team of world-leading colorectal doctors and nurses bring extensive knowledge and expertise to each of their patients, standing by you throughout each step of your treatment. Committed to your health and healing, our team is ready and available for you.

Call us at (212) 342-1155 or use our online form to schedule an appointment.

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