Colorectal cancer: signs, screening and what to do next

Colorectal cancer affects the colon or rectum and often starts as a small polyp that can be removed before it turns into cancer. That makes screening powerful — it saves lives. If you want straightforward advice on how to spot warning signs, when to get screened, and simple steps to lower your risk, keep reading.

Common signs and red flags

Watch for these changes and don’t ignore them: blood in the stool or rectal bleeding, a lasting change in bowel habits (diarrhea or constipation), stools that are narrower than usual, unexplained tiredness or iron-deficiency anemia, persistent belly pain or cramps, and unexplained weight loss. Any of these symptoms doesn’t automatically mean cancer, but they do mean you should see a doctor.

If you have a family history of colorectal cancer or known genetic conditions like Lynch syndrome, report this to your clinician — your screening schedule will likely start earlier and be more frequent.

When to get screened and what tests work

For people at average risk, major health groups now recommend starting regular screening at age 45. If you’re higher risk, screening may start much earlier. Screening detects polyps and early cancers when treatment works best.

Common screening options include:

• Colonoscopy — the gold standard. It examines the full colon and lets doctors remove polyps during the same visit. Usually done every 10 years if normal.
• FIT (fecal immunochemical test) — a yearly at-home stool test that checks for hidden blood. If positive, you’ll need a follow-up colonoscopy.
• Stool DNA test (e.g., Cologuard) — checks stool for abnormal DNA and blood; often repeated every 1–3 years depending on the test result.
• Flexible sigmoidoscopy — checks the lower colon and may be recommended in certain cases.

Talk with your clinician about which test fits you. The best test is the one you’ll actually do.

If screening finds polyps, your doctor will remove them and set a follow-up plan. If cancer is found, treatment depends on the cancer’s stage and may include surgery, chemotherapy, radiation, targeted drugs or immunotherapy.

There’s no one-size-fits-all treatment, so ask about side effects, goals of care, and follow-up testing. Getting a second opinion is reasonable for major decisions.

Want to lower your risk? Aim for these practical steps: eat more fiber and vegetables, limit red and processed meat, keep a healthy weight, exercise regularly, limit alcohol and stop smoking. Some people at average risk may benefit from low-dose aspirin, but check with your doctor before starting it.

Not sure where to start? Book an appointment, mention your family history and symptoms, and ask about the right screening test. Early action makes a big difference.