Colorectal Cancer

Colorectal cancer is cancer of the colon or the rectum, the last several feet of the digestive tract. Almost all of it starts as a polyp, a small growth on the inner lining of the bowel. Most polyps never cause trouble, but one kind, the adenoma, can slowly turn cancerous over years. That slow timeline is the whole reason screening works. A colonoscopy can find and remove a polyp before it ever becomes cancer, and can catch a cancer that has already formed while it is still small and curable. Colorectal cancer is one of the few cancers that screening can actually prevent, not just detect.

It is the third most common cancer and the third leading cause of cancer death in both men and women in the United States (American Cancer Society, Colorectal Cancer Facts and Figures 2023-2025). Caught early, while it is still confined to the bowel wall, it is highly survivable. Caught after it has spread to distant organs, it is not. The disease usually grows quietly, and by the time it causes obvious symptoms such as blood in the stool, a change in bowel habits, or unexplained weight loss, it has often been developing for years. That gap between when the cancer starts and when it announces itself is exactly where screening saves lives, and it is exactly where Black Americans have been underserved.

Early colorectal cancer often causes no symptoms at all, which is exactly why screening before symptoms appear is the point. When symptoms do show up, watch for:

• Blood in or on the stool, either bright red or very dark and tarry. Never assume rectal bleeding is just hemorrhoids.
• A lasting change in bowel habits: new constipation, diarrhea, or a narrowing of the stool that lasts more than a few days.
• A feeling that the bowel does not empty completely after a bowel movement.
• Cramping, gas, or belly pain that does not let up.
• Unexplained weight loss.
• Weakness and fatigue, often from slow, hidden blood loss that causes iron-deficiency anemia.
• Iron-deficiency anemia in a man, or in a woman past menopause, with no obvious cause. This is a red flag that on its own warrants a colonoscopy.

Screening is the whole game with colorectal cancer, because it can catch and remove precancerous polyps before they ever become cancer. Both the U.S. Preventive Services Task Force (2021) and the American Cancer Society (2018) recommend that average-risk adults start at age 45 and continue through 75.

• Start earlier if you are higher risk. A family history of colorectal cancer or advanced polyps in a parent, sibling, or child, a personal history of inflammatory bowel disease (Crohn's disease or ulcerative colitis), or an inherited syndrome such as Lynch syndrome or familial adenomatous polyposis all mean you should start before 45 and screen more often. Tell your doctor your family history.
• You have options. The USPSTF endorses colonoscopy every 10 years; a fecal immunochemical test (FIT), an at-home stool test, every year; a stool DNA-FIT test (Cologuard) every 1 to 3 years; CT colonography every 5 years; and flexible sigmoidoscopy every 5 years, or every 10 years with an annual FIT.
• The best test is the one you actually complete. A stool test done reliably every year is far better than a colonoscopy you keep putting off. Cost and access matter, and an at-home test can be mailed to you.
• A positive stool test is not the end, it is the middle. Any positive FIT or stool DNA test must be followed by a colonoscopy to find out what caused it. That follow-up colonoscopy is the step most often missed, and a positive stool test with no follow-up is a screening that did nothing. Confirm the follow-up colonoscopy is covered before you start.
• After 75, whether to keep screening is an individual decision based on your health and prior screening history (USPSTF grade C for ages 76 to 85).

Treatment depends on the stage of the cancer and where it sits in the colon or rectum. It is chosen by a team, and the plan looks very different for an early polyp-stage cancer than for one that has spread.

• Surgery is the main treatment for cancer that is still confined to the bowel. The surgeon removes the section of colon or rectum containing the tumor along with nearby lymph nodes. Some very early cancers can be removed during a colonoscopy without major surgery.
• Chemotherapy (regimens such as FOLFOX or CAPOX) is used after surgery for higher-stage disease, or to shrink and control cancer that has spread.
• Radiation is often part of rectal cancer treatment, sometimes given before surgery to shrink the tumor.
• Targeted therapy and immunotherapy are options for advanced disease, guided by biomarker testing of the tumor (including MSI or mismatch-repair status, KRAS, NRAS, BRAF, and HER2). Immunotherapy works especially well in tumors that are MSI-high or mismatch-repair-deficient. Ask whether your tumor has had complete biomarker testing, because it can open up treatments you would otherwise never be offered.
• Stage decides the odds. Colorectal cancer caught while it is still local is highly survivable; once it has spread to distant organs, survival drops sharply. That is the entire argument for screening on time.
• Where you are treated matters. Black patients have historically been referred later and less often to surgery, clinical trials, and high-volume cancer centers. Ask directly whether you are being offered the same treatment options as any other patient at your stage, and consider a second opinion.