Department of Research & Evaluation News

The updated national colorectal cancer screening guidelines that recommend screening begin at age 45 — rather than 50 — can benefit younger adults, a new Kaiser Permanente study found.

The study was published October 22, 2024, in Annals of Internal Medicine. It included 267,732 Kaiser Permanente members in Northern California, Washington, and Colorado ages 45 to 50. All received their first invitation for colorectal cancer screening along with a FIT (fecal immunochemical test) kit between January and September 2022. Kaiser Permanente Southern California was initially included in the analysis, but because it utilized a FIT opt-in approach rather than universal outreach, its data are included in the supplementary material rather than in the primary analysis.

“Kaiser Permanente Southern California observed a greater FIT completion rate in younger adults compared to those age 50, as well as compared to younger adults in other health systems, likely because of the opt-in approach it used,” said co-author Chun R. Chao, PhD, a cancer epidemiologist with the Kaiser Permanente Southern California Department of Research & Evaluation. “This study provides the first large-scale evidence of the uptake and outcomes of FIT screening in younger adults as recommended in the recent updates to clinical guidelines. As Kaiser Permanente continues to be dedicated to reducing colorectal cancer mortality, these findings can inform future planning here and at other health systems.”

The U.S. Preventive Services Task Force lowered the age to start screening in response to studies showing an increased rate of colorectal cancer in adults ages 45 to 49, said co-first author Theodore R. Levin, MD, a research scientist at the Kaiser Permanente Division of Research and a gastroenterologist with The Permanente Medical Group.

“However, the change was based entirely on simulation modeling,” he said. “We decided to collect real-world data on what happened when we began sending FIT kits to Kaiser Permanente members ages 45 to 49.”

The new study compared FIT kits returned by adults ages 45 to 49 with adults aged 50. Everyone included in the study was receiving a FIT kit for the first time. Overall, 38.9% of adults ages 45 to 49 returned their FIT kit, compared with 37.5% of adults aged 50. In the 45 to 49 age group, 3.6% of the adults had a positive result compared with 4% of the adults in the age 50 group.

In both groups, about two-thirds of the adults who had a positive FIT test had a colonoscopy within 90 days of receiving the test result. Polyp detection during the colonoscopy was slightly lower in the younger group at 58.8% compared with 67.7% in the age 50 group. However, colorectal cancer detection rates were similar: 2.8% of those ages 45 to 49 and 2.7% of those age 50 received a cancer diagnosis following their colonoscopy.

Since 2008, Kaiser Permanente’s colorectal cancer screening program has provided FIT kits to all eligible members annually, starting at age 50. In January 2022, Kaiser Permanente adopted the Task Force’s new screening recommendations and expanded its program to include members ages 45 to 49.

“Our study suggests that adults ages 45 to 49 have a colorectal cancer risk that is similar to what we see in adults age 50,” said senior author Jeffrey K. Lee, MD, MPH, a Division of Research scientist and gastroenterologist with The Permanente Medical Group. “These results provide strong support for guidelines that recommend colorectal cancer screening begin at age 45. The low number of cancers we found also provides support for initially offering younger adults a non-invasive test, like FIT, to determine which patients would benefit from a colonoscopy.”

Dr. Levin added, “Previous studies we have conducted have shown that our FIT screening program reduces deaths from colorectal cancer and reduces cancer disparities. For adults ages 45 to 49, the fact that FIT is a non-invasive and easy-to-use test makes it a good option for screening this population.”

The study was funded by the Kaiser Permanente Sidney R. Garfield Memorial Fund.

Co-authors include Christopher D. Jensen, PhD, MPH, Natalia Udaltsova, PhD, Jessica M. Badalov, MS, RD, and Charles P. Quesenberry, PhD, of the Division of Research; Andrea A. Burnett-Hartman, PhD, Brian P. Hixon, MS, Shauna R. Goldberg, MPH, and Larissa L. White, PhD, of Kaiser Permanente Colorado Institute for Health Research; Aruna Kamineni, PhD, MPH, Gaia Pocobelli, PhD, Malia Oliver, BA, and Susan C. Bradford, MS, of the Kaiser Permanente Washington Health Research Institute; Chun R. Chao, PhD, Nirupa R. Ghai, PhD, MPH, and Hina Chowdhry, MPH, of Kaiser Permanente Southern California Department of Research & Evaluation; and Joanne E. Schottinger, MD, of the Kaiser Permanente Bernard J. Tyson School of Medicine.