What Are the Stages of Colon Cancer?
Did you know March is Colon Cancer Awareness Month? Perhaps you've dressed in blue or participated in an awareness event as a survivor or in recognition of a loved one with colon cancer.
Colon and rectal cancer, or colorectal cancer -- also known as CRC -- is the third most common cancer in men and women, according to the National Cancer Institute. CRC accounts for about 8 percent of all new cancer cases. In 2016, roughly 135,000 people (or 41 out of every 100,000 people) were diagnosed with CRC. That's the bad news. The good news, says Dr. Mark Pochapin, a professor and director of the division of gastroenterology at NYU Langone Medical Center, is that due to effective screening methods and early detection, colon cancer is also one of the most preventable and curable types of cancer.
[See: 8 Questions to Ask Your Doctor About Colon Cancer.]
What Is Staging?
After your oncologist initially diagnoses you with colon cancer, he or she will use imaging tests and lab results to learn a little bit more about the specifics of your cancer. This is called staging. Staging helps your doctor decide which treatment options will likely produce the best results.
Oncologists use the American Joint Committee on Cancer TNM classification system to describe colon cancers. T describes the tumor by its size and by how far it has grown into the walls of the colon (colon cancers usually begin on the innermost wall of the colon). N specifies whether the tumor has spread to the lymph nodes (part of the immune system). Once a tumor spreads to the lymph nodes, it can travel through the lymph system to another part of your body where it can begin to grow again. M stands for metastasis, which means the tumor has spread to other parts of the body.
[See: 10 Seemingly Innocent Symptoms You Shouldn't Ignore.]
Stages of Colon Cancer
There are four stages of colon cancer: I, II, III and IV. Oncologists further divide stages II, III and IV into subcategories (for example, Stage IIa or Stage IIIb) to describe the degree to which the cancer has spread into the other layers of the colon wall or into the lymph nodes. Stage 0 cancer, or carcinoma in situ, is the presence of abnormal cells on the inner wall of your intestine. The cells are not cancerous in stage 0, but could eventually develop into cancer.
"Stages I and II are confined to the colon and rectum and vary in the amount of invasion [how much they've spread into nearby tissue]," says Dr. Kristen Ciombor, a medical oncologist and assistant professor of internal medicine for The Ohio State University.
"With stage III, the tumor has spread into lymph nodes surrounding the colon and rectum. What this means to a doctor is that the cancer has a higher likelihood of coming back, even if it's surgically removed," Ciombor says. "The standard of care is to remove the tumor mass and [one or more nearby] lymph nodes. If we see cancer cells in the lymph nodes, there's a chance it's spread beyond the colon."
In patients with stage IV cancer, the tumor has metastasized beyond the colon. Although cancer cells can travel and begin to grow any place in the body, Ciombor says many metastasized colon cancers end up in the liver because all blood from the intestines subsequently passes through the liver.
"All four stages are considered surgically resectable," Ciombor explains. This means colon cancers are treated by surgically removing the tumor or tumors. Patients who have stage III or IV colon cancer, and some patients with stage II, will likely receive chemotherapy or radiation therapy to kill any potentially remaining cancer cells left after surgery.
[See: 10 Ways to Prepare for Surgery.]
Prognosis
Early detection is important to a good colon cancer prognosis, which is why doctors are so enthusiastic about colon cancer screening. Most colon cancers begin as a growth, or polyp, on the colon wall. Polyps are common in people 50 and older and are generally benign (harmless or non-cancerous). However, they have the potential to develop into cancer. Removing them during cancer screening with a colonoscopy can prevent them from eventually developing into cancer. Colonoscopies are considered both a screening and prevention tool. Unfortunately, when a colon cancer tumor blocks or perforates (punctures) the bowel wall, the patient's prognosis is generally poor.
Most cases of colon cancers are uncovered through screening. However, if you experience any of the signs of colon cancer, see your doctor promptly. Among the possible signs of colon cancer listed by the National Institutes of Health are changes in bowel habits, blood in your stool, frequent gas pains or bloating, and unexplained weight loss. Just because you have one or more these symptoms does not necessarily mean you have colon cancer (you probably don't), but it's best to have it checked out.
Kathleen Hall is a freelance Health reporter at U.S. News. She's a writer and marketing communications professional who writes consumer health education articles for print and online publications and health care marketing material for corporate clients. Kathleen has a BS in psychology from the University of Maryland and an MBA from Virginia Commonwealth University, and she's a member of the Association of Health Care Journalists. She divides her time between Richmond, Virginia, and Bar Harbor, Maine. Kathleen is also a professional artist. Connect with Kathleen on LinkedIn or her website, or email her at Kathy@MarathonMarketingVA.
