With screening, colon cancers can effectively be detected and prevented. Though colon cancer is the third-leading cause of cancer death in the United States, one-third of Americans over age 50 are not getting screened.

“Screening saves lives and can prevent colon cancer,” said Dr. Susanne Shokoohi, a gastroenterologist at Loyola Medicine in Maywood, Ill.

More than 140,000 Americans are diagnosed with colon cancer each year. Shokoohi shares five things you need to know about the disease.

• All adults should be screened for colon cancer starting at age 50, but some groups should start even sooner.

African Americans have a higher colon cancer risk and should get their first screening at age 45. Those with a family history of colon cancer, a genetic risk for the disease or a history of inflammatory bowel or Crohn’s disease should be screened earlier, too.

“And, of course, if you have symptoms, talk to your doctor,” Shokoohi said.

• A colonoscopy is the most effective way to detect and prevent colon cancer.

While there are several ways to screen, including at-home stool tests, a colonoscopy is the most common and effective tool, Shokoohi said. It allows doctors to view your entire large intestine.

“The goal is to remove the polyp before it becomes cancerous,” Shokoohi said. “If cancer is detected, we are often finding it at an early stage—before symptoms arise—allowing us to treat the disease more effectively.”

She added getting your first screening is easy and important.

“A colonoscopy takes just one day in your life, and it can be lifesaving,” Shokoohi said in a Loyola news release.

• Colon cancer is on the rise in younger adults.

More than 90% of colon cancers are diagnosed in patients over 50. But a study last year found a troubling rise in rates among younger people.

“We are seeing a jump in the 20 to 40 age group,” Shokoohi said. “And we’re not sure if the cause is genetics, obesity or diet. I would advise patients in this age group to not ignore any symptoms, and to talk to your doctor right away if any symptoms arise.”

• Knowing the symptoms of colon cancer is vital.

The symptoms include rectal bleeding, changes in bowel habits, unintended weight loss, new or ongoing abdominal pain, as well as weakness and loss of appetite.

• Healthy diet and lifestyle choices are good prevention tools.

Diets high in fruits, vegetables, fiber and fish can help prevent colon cancer, Shokoohi said. Processed meats are linked to a higher rate of colon cancer. Smoking, obesity, heavy alcohol use and physical inactivity are other risk factors.