Colorectal cancer is becoming more prevalent among younger people and at more advanced stages, recent studies have shown.

The American Cancer Society (ACS) has found that one in five diagnoses are in people younger than age 55. Advanced disease affects three in five people.

These shifting patterns highlight the importance of screening and early detection as life-saving measures.

Colorectal cancer is the third most common cancer seen in both men and women in the U.S., according to data from the American Cancer Society.

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This year alone, it is estimated there will be 106,970 new colon cancer diagnoses and 46,050 new cases of rectal cancer

Dr. Kyle S. Eldredge, a general and colorectal surgeon in Wellington, Florida, said that in people over 50 years old, the overall incidence of colorectal cancer actually has been dropping over the last three decades due to increased screening.

"However, for people younger than 50, the incidence has been increasing by 1-2% per year since the 1990s," he told Fox News Digital. 

It’s predicted that by 2030, colorectal cancer will be the leading cause of cancer-related deaths among people ages 20 to 49.

"The exact reason for this increase in younger persons is unclear, but it is thought to be linked to diet, lifestyle and the gut microbiome," said Dr. Eldredge.

Although diagnoses have skewed younger in recent years, age is the biggest risk factor of colorectal cancer — over 90% of cases are diagnosed in those older than 45, noted Dr. Eldredge.

"Family history is another important risk factor — having a single first-degree relative with colorectal cancer can increase your risk two- or three-fold," he told Fox News Digital. 

"Other risk factors include inflammatory bowel disease — ulcerative colitis or Crohn’s disease — which are inherited disorders that lead to increased polyp growth, [as well as] smoking, obesity and alcohol intake."

In many people, early-stage colorectal cancer doesn’t cause symptoms, Dr. Eldredge said.

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Yet it’s important to know the warning signs. These include changes in bowel habits, abdominal pain, bloody stool, weakness and fatigue, rectal bleeding, anemia due to blood loss and unexplained weight loss.

"The most effective way to prevent the development of colorectal cancer is through screening," said Dr. Eldredge. 

"Early-stage cancer starts as noncancerous polyps. Through screening and removal of these polyps, the risk of colorectal cancer can be reduced by 75% to 85%."

The ACS recommends that screening should start at age 45 for those persons at average risk.

(People are considered at average risk if they do not have a personal or family history of colorectal cancer, do not have a history of inflammatory bowel disease, do not have a confirmed or suspected hereditary colorectal cancer syndrome, and have not been treated for prior cancer with radiation to the abdomen or pelvic area, per the ACS.)

"The most effective screening method is via colonoscopy, which uses a camera to directly visualize the colon," said Dr. Eldredge. "Any polyps that are found can be removed."

The ACS recommends that people of average risk get a colonoscopy every 10 years. 

For higher-risk people who have a family history of colorectal cancer or polyps, Dr. Eldredge recommends increasing the frequency to every five years.

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Another type of visual screening test is the CT (computed topography) colonography, which uses a computer to capture three-dimensional images of the colon and rectum.

There are also stool-based studies that are not as invasive, but need to be done more frequently.

"Although each test has its advantages, the best test is the one that gets done," said Dr. Eldredge.

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