11 things to know about colorectal cancer

An expert explains what to know about colorectal cancer—screenings, diagnosis, treatment and more.

Updated on April 1, 2024

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A diagnosis of colorectal cancer, which affects the colon (large intestine) and the rectum (last several inches of the large intestine) can be bring up a range of emotions. We asked surgical oncologist Jill Onesti, MD, of Mercy Health Saint Mary’s in Grand Rapids, Michigan, to explain colorectal cancer, from screening and diagnosis to treatment and recovery.

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Colorectal cancer is common

Colon cancer and rectal cancer are often grouped together under the term of colorectal cancer because they share many features. Colorectal cancer is the second leading cause of cancer deaths in the United States, according to the U.S. National Cancer Institute. It's also the fourth most common cancer, behind cancer of the breast, lungs, and prostate (a male reproductive organ which sits below the bladder and makes semen), affecting roughly 1.4 million Americans. 

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Symptoms can be hard to recognize

Colorectal cancer symptoms are subtle and are shared by many other conditions, such as irritable bowel syndrome (a digestive condition that causes abdominal discomfort, bloating, and diarrhea and/or constipation), diverticulitis (small pouches in the digestive tract that can become inflamed or infected), inflammatory bowel disease (inflammation of the digestive tract) and hemorrhoids (swollen veins in the rectum or anus).

Symptoms include:

  • Change in bowel habits, including constipation, diarrhea or narrowing of the stool
  • Rectal bleeding
  • Dark stools or blood in stool
  • Cramping or abdominal pain
  • Weakness or fatigue
  • Weight loss

However, early stage colon and rectal cancers often have no symptoms. Once symptoms are noticeable, the cancer is often at a more advanced stage, and may be harder to treat.

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Risks are a mix of lifestyle and genes

Risk factors are things that increase your chances of developing a certain medical condition. There are a number of factors that can increase your risk of colorectal cancer. Some you can control, some you can’t. To reduce your risks, avoid:

  • A diet high in saturated fat (which is solid at room temperature, like butter), and low in fiber, with lots of red and processed meat
  • A sedentary lifestyle
  • Smoking
  • Obesity
  • Drinking alcohol

Risk factors that you can’t control include age (your risk increases after age 50), a family history of colorectal cancer or colon polyps and a past history of colorectal cancer and colon polyps. Polyps are masses that grow on the lining of the colon or rectum. Most are harmless, but some can become cancerous. Most colorectal cancers develop from polyps.

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Early stage colorectal cancer is treatable

In general, the earlier a cancer is caught, the better your chances of successful treatment.  For stage I colon cancer, where the cancer has not spread beyond the colon wall, the five-year survival rate (the percentage of people who are alive five years after diagnosis) is 92 percent. The survival rate remains fairly high in colon cancer at stages II (where the cancer has spread through the wall of the colon) and III (where the cancer has spread through the all of the colon and to nearby lymph nodes, but has not spread to other parts of the body). Survival rates decrease sharply in stage IV colon cancer, when it has spread to other parts of the body. The five-year survival rate for stage IV is just 11 percent. Survival rates for rectal cancer are similar.

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Screening is important

Current screening guidelines from the American Cancer Society (ACS) recommend colonoscopies every 10 years for people of average risk. A colonscopy is a procedure in which a healthcare provider uses a long, flexible tube with a light at the end to look inside the large intetestine. Even though colorectal cancer grows slowly, screening can help find cancers when they’re in their early stages and more easily treated. However, only a little more than half the people who should get screened for colorectal cancer do so. People at average risk should start screening at age 45, according to the ACS, and people with increased risk typically should be screened earlier and more often. “We certainly try to promote surveillance and encourage people to get screened, but for a variety of reasons people don’t get their colonoscopies, so we still see plenty of people diagnosed at an advanced stage,” says Onesti. To find out when you should be screened, speak with your healthcare provider.

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There are multiple screening options

Colorectal cancer screening is not limited to a colonoscopy every 10 years. Screening tests your healthcare provider may recommend, which you may need more often than a colonoscopy, may also include:

  • Flexible sigmoidoscopy: similar to a colonoscopy, but only examines the rectum and lower colon.
  • CT colonography: Also known as a virtual colonoscopy, this test forms three dimensional pictures of your colon.
  • Barium enema: This test evaluates the colon and rectum using X-rays and a contrast solution (a substance that improves the ability to take a picture of certain body parts).
  • Fecal immunochemical test: This test involves taking a stool sample at home and sending it to a lab for analysis. The fecal immunochemical test checks for hidden blood in the lower colon and rectum.
  • Stool DNA test: Another test that requires you to send a stool sample to a lab; it looks for gene changes that often indicate colon cancer.
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Surgery is the main treatment

With colorectal cancer, surgery is performed to remove it at almost every stage, says Onesti. Early stage cancers can typically be removed during a colonoscopy. Later stage cancers usually require what’s known as a resection or colectomy. This surgery involves cutting out the cancerous section of the colon and reattaching the two ends. Surgeons try to take out all of the affected colon, as well as the lymph nodes (parts of the immune system that form white blood cells and filter foreign substances like cancer cells or infections) in the area, if necessary. “Most [early] stage I and II cancers can be treated with surgery alone,” says Onesti. Once the cancer has spread to the lymph nodes, Onesti recommends chemotherapy (chemo, drugs that kill or slow the growth of cancer) following surgery. “Most colon cancers are not treated with radiation [high-dose x-rays], but rectal cancer is usually treated with chemo and radiation at the same time.”

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Surgery may require preparation

Onesti says that strides have been made in pre-surgery preparation to make the surgery itself go more smoothly. “We have a lot more information about what patients can do ahead of their surgery,” she says. “The most important? Quit smoking.” Smoking raises your risk of complications like infections, pneumonia (infection of the lungs), blood clots and kidney problems. “You can also get started on a good nutritional program with enough protein and good, healthy food,” she says. For information of quitting tobacco and how your insurance may help, speak with your healthcare provider.

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Hospital stays are usually quick

Most colorectal surgeries are minimally invasive, meaning the surgeon makes small cuts in the abdomen to do the operation on your intestines. An open surgery requires large cuts into the abdomen and is done in specific cases, says Onesti, such as if a person might have trouble being under anesthesia (drug that causes temporary loss of feeling and/or awareness, like falling asleep), or if the cancer is growing somewhere the surgeon can’t reach with minimally invasive surgery. While open surgery is quicker, according to Onesti, it means a longer hospital stay. “The vast majority of colon cancer surgeries are minimally invasive,” Onesti says.

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Colostomy bags are often not needed

One concerning prospect of colon surgery may be the possibility of needing a colostomy bag for your waste to drain in for the rest of your life. According to Onesti, that concern is largely unfounded. “Most of the time, you won’t need a bag,” she says.

Surgeons attach the two ends of the colon to each other after a portion is removed from the middle, says Onesti, instead of attaching them to a colostomy bag worn outside the body. “There are some situations, particularly with rectal cancer, where you might need a permanent bag,” explains Onesti. “But usually there’s no bag or a temporary one.”

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Recovery can be quick

It’s common to be out of the hospital in three to five days after surgery. A healthy lifestyle before surgery can help you recover faster afterwards. “When people go home, they can resume their normal activities. They’re often tired, but that goes away in a few weeks,” she says. You’ll need to avoid lifting anything heavy for about a month, and you may be out of work for two to six weeks.

Your healthcare provider will likely want to see you every few months for four or five years, and possibly more often for certain types of rectal cancer surgery. Within a year you’ll also need a colonoscopy to check again for any polyps or tumors.

“In the past few years there’s been more focus on what healthcare providers and patients can do ahead of the surgery to minimize complications,” Onesti says. “All of our instructions for pre-surgery bowel preparation help surgery go more smoothly and get complications as close to zero as possible.”

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