Colorectal cancer is a major public health concern, but it is highly treatable when detected early. Early detection significantly increases survival rates, which is why screening is routinely recommended for average-risk individuals starting at age 45. While a definitive diagnosis requires medical procedures performed by a doctor, individuals can perform initial checks at home through symptom awareness and by using specific screening test kits. These at-home options provide convenient, non-invasive ways to screen for signs of the disease.
Recognizing Warning Signs
Observing changes in your body and bowel habits is the first way to check for potential issues at home. A persistent change in the consistency or frequency of bowel movements, such as new-onset diarrhea or constipation lasting more than a few days, warrants attention. Changes in stool shape, like stools that appear narrower or “ribbon-like,” can indicate an obstruction in the colon.
Rectal bleeding may manifest as bright red blood on toilet paper or in the toilet bowl, or as dark, tarry stools, which suggest blood has been digested. Persistent abdominal discomfort, including cramping, gas pains, or a feeling that the bowel does not empty completely, should also be noted. Systemic symptoms like unexplained weight loss and chronic fatigue can arise from slow, ongoing blood loss leading to anemia.
While these symptoms can often be caused by less serious conditions like hemorrhoids or irritable bowel syndrome, their presence or persistence should prompt a consultation with a healthcare provider. Symptoms indicate a need for a diagnostic workup, even if a recent screening test was negative. Symptom monitoring complements, but does not replace, formal screening.
Understanding At-Home Screening Options
At-home screening involves tests that analyze a stool sample for markers that suggest the presence of cancer or precancerous growths. These tests are designed for people at average risk who do not currently have symptoms. The Fecal Immunochemical Test (FIT) is a common type that looks for hidden (occult) blood in the stool, specifically targeting human hemoglobin from the lower gastrointestinal tract.
The FIT is typically performed annually and does not require any dietary or medication restrictions before sample collection. It uses antibodies to detect blood, offering better accuracy than its predecessor, the Guaiac Fecal Occult Blood Test (gFOBT). The gFOBT also detects blood but uses a chemical reaction that can react to certain foods, such as red meat, necessitating temporary dietary changes.
Another advanced option is the multitarget stool DNA test, commonly known by the brand name Cologuard. This test not only searches for hidden blood but also analyzes the stool sample for altered DNA that is shed from cancerous or precancerous polyp cells. Stool DNA tests are generally recommended for use every three years.
The DNA test has a higher sensitivity for detecting colorectal cancer, meaning it is more likely to correctly identify cancer if it is present. However, it also has a higher rate of false-positive results compared to the FIT. All stool tests are screening tools intended to detect signs of disease in asymptomatic individuals, not diagnostic tools that definitively confirm cancer.
Interpreting Results and Next Steps
The result of an at-home screening test will be either negative or positive, dictating the next step in your health monitoring. A negative result means the test did not detect blood or altered DNA above the cutoff threshold. For a negative result, the recommended action is to continue with the established screening schedule, typically annual for FIT or every three years for a stool DNA test.
A positive result on any at-home screening test requires an immediate follow-up with a diagnostic colonoscopy. A positive result indicates that blood or altered DNA was found, which could be due to cancer, large polyps, or non-cancerous conditions like hemorrhoids or ulcers. The colonoscopy is necessary to visually examine the entire colon, determine the source of the positive result, and remove any detected polyps.
A positive screening result does not automatically mean a cancer diagnosis, but it does mean a diagnostic procedure is mandatory. If you begin to experience any warning signs, consult a healthcare provider immediately for a full clinical evaluation, regardless of the screening result.