A new Kaiser Permanente study found lowering the screening age for colorectal cancer led to earlier cancer diagnoses.

“The U.S. Preventive Services Task Force lowered the age to start screening after studies showed colorectal cancers in adults ages 45 to 49 were on the rise,” said study author Theodore R. Levin, MD, a research scientist at the Kaiser Permanente Division of Research (DOR) and a doctor with The Permanente Medical Group (TPMG). “We studied what happened at Kaiser Permanente when we began following those guidelines.”

Recently published in Annals of Internal Medicine, the study included more than 260,000 Kaiser Permanente members in Northern California, Washington, and Colorado ages 45 to 50. Everyone in the study was being screened for colorectal cancer for the first time.

Lowering the age for screening

At Kaiser Permanente, screening begins with a stool test called FIT. (FIT is short for fecal immunochemical test.) Since 2008, Kaiser Permanente has sent a FIT kit to screen for colon cancer every year to all eligible members ages 50 and older. In January 2022, Kaiser Permanente began to also offer FIT kits to members ages 45 to 49.

Dr. Levin and his team compared the FIT results of the adults ages 45 to 49 with the adults who were 50. They found that, overall, about 38% in both groups returned their FIT tests. Among those ages 45 to 49, 3.6% had a positive test. In those age 50, 4% has a positive test.

A colonoscopy is recommended after a positive FIT test. In both groups, about two-thirds of the adults who had a positive FIT test had a colonoscopy within 90 days of getting their test result.

During a colonoscopy, doctors may find small growths, called polyps. Over time polyps may become cancers. The study showed doctors found a polyp in 59% of the younger adults. They also found polyps in 68% of those age 50. A colonoscopy can also find cancer. The study showed that close to 3 percent of those ages 45 to 49 and those age 50 had a cancer found during the colonoscopy.

“These results provide strong support for guidelines that recommend colorectal cancer screening begin at age 45,” said senior author Jeffrey K. Lee, MD, MPH, a DOR research scientist and gastroenterologist with Kaiser Permanente in San Francisco. “The low number of cancers we found also provides support for offering younger adults a test like FIT to determine which patients would benefit from a colonoscopy.”

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