A new study has found that screening women for colorectal cancer (CRC) starting at age 45 reduced their risk 50 to 60 percent.

The research from Massachusetts General Hospital, published in JAMA Oncology, supports recommendations from the American Cancer Society and the US Preventive Services Task Force to start screening at 45, a response to the increase in CRC cases in younger patients.

“While there’s been an alarming increase in the incidence of colorectal cancer in recent decades in younger individuals, screening has largely been focused on people over 50,” says Andrew Chan, MD, MPH, a gastroenterologist and epidemiologist at MGH, and senior author of the study. “Our work provides first-of-its-kind data to show that initiating screening at a younger age can reduce an individual’s risk of colorectal cancer and the population’s overall incidence of cancer, thus demonstrating the substantial impact of earlier screening on both individual and population-wide scales.”

The study looked at records for 111,801 women in the Nurses’ Health Study, comprised of registered nurses from 14 states. Researchers found a 50 to 60 percent lower risk of CRC among women who started endoscopy screening at age 45 compared to those who had no screening. They also learned that starting screening from 45 to 49 resulted in a significant drop of CRC cases in the population diagnosed through age 60, compared to women starting screening between 50 and 54.

While the overall number of CRC cases has been on the decline in the US, the incidence among people under 50 has increased 51 percent from 1974 to 2013. It is only recently that screening has been recommended to begin before 50.

“Any trepidation that clinicians might have had about the effectiveness of CRC screening at a younger age will hopefully be allayed by these results,” he says. “Our data show that we have an effective tool to address the epidemic of colorectal cancer among younger adults, and hopefully this will encourage physicians to have a conversation about screening with their younger patients which, in turn, will motivate them to follow through and get screened.”