New York, Oct 12 (IANS): Women who are overweight or obese have up to twice the risk of developing colorectal cancer before age 50, warn researchers.

Compared with women with the lowest body mass index (BMIs), 18.5-22.9 kilograms per square meter, women with the highest BMIs, greater than 30, had almost twice the risk of early-onset of colorectal cancer, Xinhua news agency reported.

"Our findings really highlight the importance of maintaining a healthy weight, beginning in early adulthood for the prevention of early-onset colorectal cancer," said Yin Cao, Assistant Professor of surgery in the Division of Public Health Sciences at Washington University.

"We hypothesised that the obesity epidemic may partially contribute to this national and global concern in early-onset colorectal cancer rates, but we were surprised by the strength of the link and the contribution of obesity and weight change since early adulthood," Cao said.

For the study, published in the journal JAMA Oncology, the team included data from 85,256 women aged 25 to 44.

They emphasised that this is an association study, which does not establish that increasing weight is a cause of early-onset colorectal cancer.

More studies are needed to uncover the best ways to identify young people at high risk of colorectal cancer at younger ages.

The American Cancer Society recently lowered the recommended age at which most people should undergo a first screening colonoscopy. The new guidelines recommend screening beginning at age 45, down from the previous recommendation of age 50.