Colon-Cancer Q&A: What to Know

By Brianna Abbott

The cancer might not cause symptoms at the beginning, but symptoms can include a change in bowel movements, bleeding, abdominal pain, fatigue and unintended weight loss.

How common is colorectal cancer? How deadly is it?

Colorectal cancer is the fourth-most-common type of cancer, after breast, lung and prostate cancer, according to the National Cancer Institute. There will be an estimated 147,950 new cases in 2020 and 53,200 estimated deaths, which is 8.8% of all cancer-related deaths.

The cancer is more prevalent in men than women and is more prevalent among Black Americans than other ethnicities, said Kimmie Ng, director of the Young-Onset Colorectal Cancer Center at Dana-Farber Cancer Institute in Boston.

It is most common among people ages 65 to 74, though more than one-tenth of cases occur in people under the age of 50, said Dr. Ng.

How deadly the cancer is largely depends on how far it spreads. But colorectal cancer is the second-most-common cause of cancer death in the U.S., behind lung cancer.

What is ‘young onset’ colorectal cancer, and how common is it?

Someone with a colorectal-cancer diagnosis under the age of 50 is considered to have “young onset” colorectal cancer.

Rates of new colorectal-cancer cases and deaths have decreased overall in recent decades. But among adults under the age of 55, the incidence increased by 51% from 1994 to 2014 in the U.S., and mortality increased 11% from 2005 to 2015, according to the NCI. By 2030, colon-cancer incidence is expected to double among those under 50, according to Dana-Farber Cancer Institute, and rectal-cancer incidence is expected to quadruple.

Younger people are often likely to get diagnosed at later stages of the disease, making it more difficult to treat.

What is causing the increase in that age group?

Oncologists aren’t sure, though changes in diet and exercise, obesity, biological or environmental factors, or a combination of those things, might contribute.

A handful of institutions, including Dana-Farber Cancer Institute in Boston and Memorial Sloan Kettering Cancer Center in New York, have opened centers specifically to research and treat young-onset colorectal cancer in the past few years.

“It is urgent that we understand why colorectal cancer is happening in young people so we can develop new prevention and treatment strategies,” said Dr. Ng. “The heartbreaking loss of Chadwick Boseman truly amplifies our mission to effectively treat and cure young-onset colorectal cancer.”

How is colon cancer treated?

Potential treatments include surgery, especially for an early-stage cancer, as well as chemotherapy, targeted drug therapy, radiation therapy and immunotherapy. The treatment largely depends on the stage of the cancer, or how far it has spread.

What about screening?

Screening for colon cancer in people without symptoms can help doctors find precancerous polyps and remove them before they turn into cancer, or it can identify cancer in its earlier stages, when it is easier to treat.

The United States Preventive Services Task Force recommends regular screening, whether that is stool tests, a colonoscopy or other types of tests, between the ages of 50 to 75, according to its 2016 guidelines. On average, a stool test (which looks for blood in the stool or genetic signs of cancer) should be done every year to three years, while a colonoscopy should be done once every 10 years, according to the Centers for Disease Control and Prevention.

The American Cancer Society updated its guidelines in 2018 to recommend that people get screened for colorectal cancer starting at age 45 because of the rising rates of colorectal cancer among younger adults.

Write to Brianna Abbott at brianna.abbott@wsj.com