DEAR MAYO CLINIC: My cousin, who's in her 30s, was recently diagnosed with colorectal cancer. I've always thought of colorectal cancer as something that affects older adults. Why are more young people being diagnosed with colorectal cancer, and is it different when it happens at a younger age?
ANSWER: For many years, colorectal cancer was considered a disease that mainly affected older adults, and screening traditionally began at age 50. Today, however, doctors are diagnosing more people in their late 20s, 30s and 40s.
This shift led to national guidelines being lowered; they now recommend 45 as the age to begin routine colorectal cancer screening. In the past, doctors believed colon polyps, small growths in the colon or rectum, typically took about 10 years to become cancerous. That understanding helped determine when screening should begin.
Colorectal cancer screening
Colonoscopy and flexible sigmoidoscopy are considered the gold standard for screening. Both require bowel preparation the day before, sedation during the procedure and someone to drive you home. These procedures also allow doctors to remove polyps during the same exam.
Stool-based tests are another option. Some look for hidden blood, while others look for cancer-related DNA. These tests generally must be done annually and, if positive, require follow-up with a colonoscopy. For people at higher risk, such as those with a first-degree relative with colorectal cancer, a colonoscopy or sigmoidoscopy is typically recommended instead of stool testing alone.
While screening is important, researchers are still working to understand why more younger adults are being diagnosed.
So far, there isn't a single explanation. In some cases, inherited conditions, such as Lynch syndrome, and inflammatory bowel diseases like Crohn's disease or ulcerative colitis, increase the risk of colorectal cancer. Researchers are studying other possible genetic, environmental and lifestyle factors, but more research is needed to fully understand the rise.
Smoking, alcohol use, higher red meat intake, lower physical activity and sedentary habits are often discussed, but much of the evidence comes from observational studies, and firm conclusions are still lacking. Researchers are also examining whether early life exposures, including during pregnancy, may play a role.
Younger adults sometimes experience delays in diagnosis because they may not yet qualify for screening and symptoms can be subtle. Some data suggest younger patients may have multiple medical visits before receiving a diagnosis, which can contribute to detection at a later stage.
Warning signs or symptoms
Symptoms that young adults should watch for include:
- A consistent change in bowel habits, such as ongoing constipation or diarrhea.
- Blood in the stool, whether bright red or dark.
- Unintentional weight loss.
- Abdominal pain that doesn't go away.
- Iron-deficiency anemia.
Some people attribute rectal bleeding to hemorrhoids, but any blood in the stool should be evaluated. Iron-deficiency anemia, particularly microcytic anemia found on blood tests, should prompt evaluation to determine whether bleeding may be occurring in the digestive tract. That workup often includes a colonoscopy.
Symptoms that persist for several days to weeks should be evaluated.
Treatment options for colorectal cancer
Treatment approaches, including surgery, chemotherapy, radiation therapy and, in some cases, immunotherapy, aren't different based on age alone. However, younger patients often face additional life considerations. Many are balancing school, careers and family responsibilities along with financial pressures. Fertility is also an important concern, since these treatments can affect the ability to have children. For that reason, fertility counseling is often discussed before treatment begins.
In certain rectal cancers, treatment strategies are evolving. Doctors are working on tailoring therapy to reduce long-term side effects while maintaining cure rates.
There's ongoing research focused on prevention, including studies of the gut microbiome and how environmental exposures may influence cancer risk. Advocacy groups such as Fight Colorectal Cancer and the Colorectal Cancer Alliance provide education and support for patients and families. They also work closely with researchers to help ensure that patients have a voice in how clinical trials are designed and conducted.
While much remains to be understood about why colorectal cancer is increasing in younger adults, awareness, timely evaluation of symptoms and appropriate screening remain key.
Christina Wu, M.B., B.Ch., M.D., Medical Oncology, Mayo Clinic in Arizona