Colorectal Cancer

Causes & Risk Factors

Colorectal cancer risk arises from a combination of age-related, hereditary, and lifestyle factors:

•  Age — risk increases significantly after age 50, though colorectal cancer can occur at younger ages.

•  Personal or family history — a personal history of colorectal polyps or cancer, or a family history in a first-degree relative, increases risk.

•  Inherited syndromes — Lynch syndrome and familial adenomatous polyposis (FAP) are well-established hereditary causes of colorectal cancer.

•  Inflammatory bowel disease — long-standing ulcerative colitis or Crohn's disease affecting the colon increases risk.

•  Diet and lifestyle — diets high in red or processed meat, obesity, physical inactivity, smoking, and heavy alcohol use are all associated with increased risk.

Symptoms & When to Test

Early colorectal cancer often causes no symptoms, which is why age-appropriate screening is recommended even without symptoms — but certain symptoms warrant prompt evaluation.

•  A persistent change in bowel habits (diarrhea, constipation, or narrowing of stool) lasting more than a few weeks

•  Blood in the stool, or dark/tarry stools

•  Unexplained abdominal pain or cramping

•  Unexplained weight loss

•  Unexplained iron-deficiency anemia

•  A feeling of incomplete bowel emptying

When Should You Consider Testing?

Persistent changes in bowel habit, visible blood in stool, unexplained weight loss, or unexplained anemia should prompt medical evaluation, particularly in individuals over 45–50 or those with a family history of colorectal cancer or polyps.

Why Tests Are Combined

MMR protein IHC (or MSI testing) and KRAS/NRAS/BRAF molecular testing answer entirely different clinical questions — MMR/MSI status has both prognostic value and helps flag patients for Lynch syndrome evaluation, while KRAS/NRAS/BRAF status determines eligibility for specific targeted therapies (anti-EGFR treatment is generally not effective when these genes carry certain mutations).

Because a tumor's response to targeted therapy depends on its specific molecular profile, testing multiple genes rather than relying on histopathology alone allows the oncology team to select a treatment strategy matched to the tumor's actual biology.

When MMR deficiency or high MSI is identified, this finding on its own does not confirm Lynch syndrome — it flags the case for further evaluation, which may include germline genetic testing, since MMR deficiency can also occur sporadically without being inherited.

Tests Available at NPL

Most tumor molecular tests, histopathology, IHC, and genetic tests do not require fasting. However, some blood-based investigations ordered alongside cancer testing may have specific preparation requirements. Please follow the instructions provided by your doctor or NPL.

Home Sample Collection

Colorectal cancer diagnosis requires a tissue biopsy, typically obtained during colonoscopy by a gastroenterologist or surgeon — this is not a home sample collection service.

Once your biopsy or surgical sample is obtained, NPL arranges secure transport of the tissue to our accredited laboratory for histopathology, IHC, and molecular testing.

Reports are delivered securely to your treating gastroenterologist, surgeon, or oncologist, and to you, within the timeframe specified for the tests ordered.

When to See a Doctor

•  Persistent change in bowel habits lasting more than a few weeks

•  Visible blood in stool, or dark/tarry stools

•  Unexplained abdominal pain or weight loss

•  Unexplained iron-deficiency anemia

•  Family history of colorectal cancer, polyps, or Lynch syndrome — discuss appropriate screening timing with your doctor