Colorectal Cancer: Symptoms, Screening, and Treatment Options

Colorectal cancer is cancer of the colon or rectum. It is one of the most common cancers in the United States, and it is rising in adults under 50. The good news: it is one of the few cancers that screening can prevent, by finding and removing polyps before they turn into cancer.

Symptoms

Many early colorectal cancers cause no symptoms, which is why screening matters. See a doctor if you have:

• Blood in the stool or rectal bleeding
• A change in bowel habits (diarrhea, constipation, or thinner stools) lasting more than a few weeks
• Belly pain, cramping, or bloating that does not go away
• Unexplained weight loss or tiredness
• Iron-deficiency anemia

Do not assume bleeding is from hemorrhoids, especially if you are 45 or older.

Risk factors

• Age: risk rises with age, though cases in younger adults are increasing.
• Family history of colorectal cancer or advanced polyps, especially in a parent, sibling, or child, or in a relative diagnosed before 60.
• Inherited syndromes, such as Lynch syndrome and familial adenomatous polyposis (FAP).
• Inflammatory bowel disease: long-standing ulcerative colitis or Crohn's disease of the colon.
• Lifestyle: diets high in red and processed meat and low in fiber, smoking, heavy alcohol use, obesity, and inactivity.
• Black Americans have higher rates, and men are slightly more likely than women to develop it.

When to start screening

Average risk

Start at age 45, as recommended by the U.S. Preventive Services Task Force and the American Cancer Society. Continue through age 75; after that, decide with your doctor.

Higher risk

• Family history: if a first-degree relative (parent, sibling, or child) had colorectal cancer or an advanced polyp before age 60, or two first-degree relatives at any age, start colonoscopy at age 40, or 10 years before the youngest relative's diagnosis, whichever comes first, and repeat every 5 years. If one first-degree relative was diagnosed at 60 or older, start at 40.
• Inflammatory bowel disease: start surveillance colonoscopy about 8 years after colitis symptoms begin. If you have ulcerative colitis with primary sclerosing cholangitis (PSC), start at diagnosis and repeat every year.
• Inherited syndromes need earlier and more frequent colonoscopy, often with genetic counseling.

Screening options

• Colonoscopy, every 10 years if normal. The only test that finds and removes polyps in the same exam. If polyps are found, the next exam may be in 3 to 10 years depending on their number, size, and type. Eligible adults can schedule a screening colonoscopy without a separate office visit through our direct access colonoscopy program.
• FIT (fecal immunochemical test), every year. A simple home stool test for hidden blood.
• Stool DNA test (Cologuard or Cologuard Plus), every 3 years. A prescription home test that looks for blood and DNA changes from cancer and large polyps. It finds more cancers than FIT but has more false positives.
• CT colonography (virtual colonoscopy), every 5 years.
• Blood tests (such as Shield) are FDA approved for average-risk adults, but they miss more cancers and most precancerous polyps. They are not a substitute for colonoscopy or a stool test.

Any positive stool, blood, or CT test needs a follow-up colonoscopy. See colon polyps and colon cancer screening for more.

Diagnosis and staging

Colorectal cancer is diagnosed with a biopsy during colonoscopy. CT scans of the chest, abdomen, and pelvis show whether it has spread, and rectal cancers usually also get a pelvic MRI. The tumor is tested for mismatch repair (MMR/MSI) status, which guides treatment and screens for Lynch syndrome. A CEA blood test is used to follow treatment.

Treatment options

Treatment depends on the stage and where the cancer is. A team that includes a gastroenterologist, surgeon, medical oncologist, and radiation oncologist plans care together.

• Removal during colonoscopy: some very early cancers inside a polyp can be fully removed during colonoscopy.
• Surgery: removing the part of the colon or rectum with the cancer and nearby lymph nodes (colectomy or proctectomy), often with minimally invasive or robotic techniques.
• Chemotherapy: after surgery for stage III and some stage II colon cancers to lower the chance of return, and for cancer that has spread.
• Radiation and chemotherapy for rectal cancer: often given before surgery. Some patients whose tumor disappears completely may be able to avoid surgery with close monitoring.
• Immunotherapy: for cancers with MMR deficiency (MSI-high), immunotherapy can be highly effective, and in some rectal cancers it has made the tumor disappear.
• Targeted therapy: medicines that block specific growth signals, used for advanced cancer based on tumor testing.
• Treating spread to the liver or lungs: surgery, ablation, or other local treatments can sometimes remove these areas.

After treatment, follow-up includes office visits, CEA tests, CT scans, and colonoscopy, usually 1 year after surgery.

Lowering your risk

• Get screened on time, starting at 45.
• Eat more vegetables, fruit, whole grains, and fiber, and less red and processed meat.
• Stay active, keep a healthy weight, don't smoke, and limit alcohol.
• Tell us about your family history so we can recommend the right screening plan.

Make an appointment

Our gastroenterologists in Temple City care for patients from Arcadia, San Gabriel, Pasadena, Monrovia, Monterey Park, and across the San Gabriel Valley. We accept most PPO plans (see accepted insurances), and our doctors speak English, Vietnamese, and Mandarin. Schedule an appointment or call 626-898-4560.

This article is for general education and is not a substitute for medical advice. Talk with your doctor about your own health.