Colon cancer and young adults is an increasingly important health topic as colorectal cancer rates rise among people younger than 50. Colorectal cancer includes cancers that begin in the colon and rectum, and early-onset colorectal cancer generally refers to colorectal cancer diagnosed before age 50.
The increase is significant. According to the American Cancer Society, colorectal cancer rates among adults younger than 50 continue to rise, and about three out of four colorectal cancers in this age group are diagnosed after the cancer has already reached a regional or distant stage.
Colorectal cancer can develop in young people who appear healthy and have no obvious family history. Recognizing symptoms, understanding your risk factors, and knowing when to talk with your doctor can help lead to an earlier diagnosis.
THE BASICS: Colon cancer is not only a disease of older adults. Young adults should know the warning signs, including rectal bleeding, persistent changes in bowel movements, abdominal pain, and iron-deficiency anemia. Average-risk adults should begin colorectal cancer screening at age 45, but symptoms at any age should be evaluated.
Why is colorectal cancer increasing in young adults?
Researchers are still trying to understand why colorectal cancer cases are increasing in younger adults. There does not appear to be one explanation.
Research is exploring many possible contributors, including genetics, obesity, a sedentary lifestyle, environmental exposures, and lifestyle habits such as diet and physical activity. Researchers are also studying whether changes in the gut microbiome may play a role.
The microbiome includes the large community of microorganisms that live in the digestive tract. Scientists are studying how these microorganisms interact with diet, inflammation, metabolism, and other factors that could influence colorectal cancer risk.
What are the colon cancer warning signs in young adults?
Symptoms of colorectal cancer can occur at any age. Four warning signs identified by research highlighted by the National Cancer Institute are rectal bleeding, abdominal pain, diarrhea, and iron-deficiency anemia.
Other symptoms can include persistent constipation, changes in the shape or appearance of stool, unusual stools, unexplained fatigue, bloating, and unintentional weight loss.
Young adults should pay attention to changes that are persistent, unexplained, or different from their normal bowel movements. Having these symptoms does not mean you have cancer, but they should not automatically be dismissed because of your age.
Rectal bleeding and changes in bowel movements
Blood in or on your stool can have many causes, including hemorrhoids, but rectal bleeding can also be a symptom of colon or rectal cancer.
Persistent diarrhea, constipation, narrower stools, or other changes in your usual bowel habits should also be discussed with your healthcare provider, particularly when they occur with bleeding, abdominal pain, or unexplained fatigue.
Abdominal pain and iron-deficiency anemia
Persistent abdominal cramping, pain, or discomfort can be another warning sign. In some people, a colorectal tumor may also bleed slowly without causing visible blood in the stool.
Over time, this blood loss can lead to iron-deficiency anemia, which may cause fatigue, weakness, dizziness, or shortness of breath. Unexplained iron-deficiency anemia deserves further evaluation, even in younger adults.
What does new research on AST and ALT mean for young adults?
Research published by Epic Research in September 2026 found an association between lower AST and ALT levels and early-onset colorectal cancer among adults ages 18–44 undergoing their first colorectal cancer screening.
AST, or aspartate aminotransferase, and ALT, or alanine aminotransferase, are enzymes commonly measured during routine blood testing. In the study, an AST below 14 U/L was associated with a 65% higher likelihood of early-onset colorectal cancer compared with levels of 14–29 U/L. An ALT below 14 U/L was associated with a 68% higher likelihood.
These findings do not mean that low AST or ALT levels diagnose colorectal cancer. They also do not mean that everyone with low liver enzyme levels needs a colonoscopy. The research identifies an association that may help scientists better understand which younger adults could be at increased risk.
Current colorectal cancer screening recommendations have not changed because of these findings.
What are the risk factors for colon cancer in young people?
Many younger people diagnosed with colorectal cancer do not have an obvious inherited cause. However, several risk factors can increase a person's likelihood of developing the disease.
These include a personal or family history of colorectal cancer or colon polyps, certain inherited genetic conditions, inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, smoking, heavy alcohol use, obesity, physical inactivity, and certain dietary patterns.
Family history and Lynch syndrome
A family history of colorectal cancer or certain polyps can increase your risk. The age at which your relative was diagnosed and how closely you are related can affect screening recommendations.
Inherited conditions can also substantially increase risk. Lynch syndrome is the most common inherited colorectal cancer syndrome. Other inherited conditions, including familial adenomatous polyposis (FAP), can cause numerous colon polyps and significantly increase cancer risk.
If colorectal cancer or related cancers occur frequently in your family, your healthcare provider may recommend genetic counseling or earlier screening.
When should colorectal cancer screening begin?
The American Cancer Society recommends that adults at average risk begin regular colorectal cancer screening at age 45.
People at increased risk may need early screening before age 45. This can include people with a strong family history, certain inherited cancer syndromes, inflammatory bowel diseases, or a personal history of certain colorectal polyps.
Screening recommendations apply to people who do not have symptoms. If you have rectal bleeding, unexplained iron-deficiency anemia, persistent abdominal pain, or ongoing changes in bowel habits, talk with your doctor regardless of your age.
Do young adults need a colonoscopy?
Not every young adult needs a colonoscopy. However, a healthcare provider may recommend diagnostic testing when symptoms or risk factors raise concern for colorectal cancer.
Evaluation may begin with your primary care provider. Depending on your symptoms and medical history, you may be referred to gastroenterologists, doctors who specialize in conditions affecting the digestive system.
A colonoscopy allows a doctor to examine the inside of the colon and rectum, identify abnormal areas, remove certain polyps, and take tissue samples when necessary.
Why early detection matters for younger patients
Colorectal cancer can be easier to treat when it is diagnosed before it has spread. Unfortunately, younger patients are often diagnosed at later stages.
American Cancer Society data show that three out of four colorectal cancers diagnosed in people younger than 50 are regional or distant-stage disease. Half of colorectal cancer diagnoses under age 50 occur among people ages 45–49, the age group now eligible for routine screening.
Recognizing symptoms and following screening recommendations may help find cancer earlier.
What treatment options are available for young adults with colon cancer?
Treatment options depend on where the cancer started, its stage, the characteristics of the tumor, and the patient's overall health.
Treatment may include surgery, chemotherapy, radiation therapy, targeted therapy, immunotherapy, or a combination of treatments. Testing the tumor for certain biomarkers can also help doctors determine whether particular targeted treatments or immunotherapies may be appropriate.
Younger age does not automatically determine which treatment is best. Treatment decisions should be individualized with the patient's cancer care team.
Clinical trials for young adults with colorectal cancer
Clinical trials study new ways to prevent, diagnose, and treat colorectal cancer. Depending on the cancer's stage and molecular characteristics, a clinical trial may provide access to a treatment approach that is still being studied.
If you are diagnosed with colorectal cancer, ask your healthcare team whether there are clinical trials appropriate for your diagnosis. Trials may investigate new medications, combinations of existing treatments, targeted therapies, immunotherapies, or other approaches.
Colon cancer prevention and lifestyle changes
Not all colorectal cancers can be prevented, and developing cancer is not a person's fault. However, certain lifestyle changes may help reduce colorectal cancer risk while supporting overall health.
Regular physical activity, maintaining a healthy weight, avoiding tobacco, limiting alcohol, and eating a balanced diet with fruits, vegetables, beans, whole grains, and other fiber-rich foods are healthy habits. Limiting processed meats and large amounts of red meat may also help reduce risk.
Researchers continue to investigate how lifestyle, metabolism, inflammation, environmental exposures, and the gut microbiome may contribute to early-onset colorectal cancer.
When should young people talk to a doctor?
Do not ignore rectal bleeding, blood in your stool, unexplained iron-deficiency anemia, persistent abdominal pain, ongoing changes in bowel movements, unexplained fatigue, or unintentional weight loss simply because you are young.
Research highlighted by the National Cancer Institute found that having one of four warning signs—rectal bleeding, abdominal pain, diarrhea, or iron-deficiency anemia—was associated with nearly twice the likelihood of an early-onset colorectal cancer diagnosis. Having three or more was associated with about six times the likelihood.
These symptoms are much more commonly caused by conditions other than cancer. However, symptoms that persist, recur, or cannot be explained deserve medical evaluation.
What young adults should remember about colon cancer
Colon cancer is no longer a disease that affects only older adults. As early-onset colorectal cancer becomes more common, awareness among young people, patients, and healthcare providers is increasingly important.
Know your family history, understand your risk factors, follow colorectal cancer screening recommendations, and pay attention to persistent changes in your body. If something does not feel right, talk with your healthcare provider rather than assuming you are too young for colorectal cancer.
New findings involving AST and ALT may eventually help researchers better identify people at increased risk, but these blood tests are not currently used to diagnose or screen for colorectal cancer. For now, recognizing warning signs, understanding personal risk, and participating in recommended screening remain important tools for finding colorectal cancer earlier.
