Colorectal cancers are the third-leading cause of cancer-related deaths for men and fourth for women, but is the second overall when men and women are combined, according to data compiled by the American Cancer Society.
In 2026, it is expected to kill about 55,230 people this year.
According to the Mayo Clinic, colon cancer “is a growth of cells that begins in a part of the large intestine called the colon.”
Rectal cancer is found in the final portion of the colon.
Colorectal cancer is a condition that combines the two cancers into one illness.
Colon cancer
Colon cancer typically affects older adults, but it can be found at any age.
Colon cancer starts as polyps, or clumps of cells. Typically, they aren’t cancerous but can turn into colon cancer over time.
Most people don’t have symptoms when cancer develops, and symptoms depend on the size and location of the cancer.
The Mayo Clinic said it is not known what causes most colon cancers, but there are risk factors including being over than 50, being Black, history of colorectal cancer or polyps, having inflammatory bowel disease, inherited conditions, family history, low fiber but high fat diet, lack of exercise, diabetes, obesity, smoking, alcohol use and radiation for other cancer treatments.
Symptoms of colon cancer
The symptoms of colon cancer include:
- Change in bowel habits
- Rectal bleeding or blood in stool
- Ongoing discomfort in the belly
- Feeling that the bowel is still full after using the bathroom
- Weakness
- Tiredness
- Losing weight without trying.
Prevention
Doctors recommend starting screenings for colon cancer at 45 if people have an average risk; however, those with a higher risk should start earlier.
You can also make lifestyle changes to prevent colon cancer from developing, including eating fruits, vegetables and whole grains; drinking in moderation, if at all; stopping smoking; exercising, and maintaining a healthy weight.
There are some medications to reduce risk, but the Mayo Clinic says they are usually reserved for people with a high risk.
Testing
Colon cancer can be found in a few ways, including a digital rectal exam and a fecal occult blood test. There is also the option of using devices in a sigmoidoscopy or colonoscopy. There is also a virtual colonoscopy, the National Cancer Institute said.
When tissue is removed, it will undergo a biopsy or be viewed under a microscope, looking for cancer signs.
Once cancer is detected, a person may undergo more testing, including a CT scan, MRI, PET scan, X-ray, surgery, lymph node biopsy or carcinoembryonic antigen assay, according to the National Cancer Institute.
Treatment
If colon cancer is found, there are treatment options which include surgery, chemotherapy, radiation, targeted therapy and immunotherapy, the National Cancer Institute said. The treatment will depend on the stage of cancer that is found.
Keep in mind, colon cancer can come back after it has been treated, and can return in other parts of the body.
Rectal cancer
As the name suggests, rectal cancer starts in cells found in the rectum. It is similar to colon cancer, but it is different, mainly because of the proximity of the rectum to other organs and parts of the body. Rectal cancer removal can be difficult, according to the Mayo Clinic.
Typically, it involves surgery to remove the cancer, but can also include chemotherapy, radiation or both.
Symptoms
Symptoms include:
- Change in bowel habits
- Feeling that the bowel doesn’t empty
- Abdominal pain
- Rectal bleeding
- Narrow stool
- Weight loss without trying
- Weakness or fatigue
- A lump in the rectum
The Mayo Clinic reminds that rectal bleeding may not be cancer, but instead hemorrhoids. But that bleeding is typically bright red and happens after going to the bathroom. Cancer-related bleeding may be red, but also brown and can happen at any time. Any bleeding should be checked by a doctor because it is hard to tell the difference.
Causes
As with colon cancer, the causes of rectal cancer aren’t known, the Mayo Clinic said.
Most rectal cancers are adenocarcinomas, or a cancer that starts in gland cells.
Risk factors are similar to those of colon cancer.
Prevention
Screening is the key to prevention, with tests typically starting at the age of 45, but if you are at higher risk than normal, you can start earlier.
Like colon cancer, your diet, alcohol habits and exercise can help prevent rectal cancer development.
Testing
There are several tests that can be done for rectal cancer, including: guaiac-based fecal occult blood test (gFOBT), fecal immunochemical test (FIT), and FIT-DNA tests.
There are also the sigmoidoscopy, the colonoscopy and a virtual colonoscopy that may also find indications of rectal cancer.
Treatment
Treatment for rectal cancer can include surgery, chemotherapy, radiation therapy, targeted therapy and immunotherapy, the Mayo Clinic said.
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