New York, July 15 (IANS): Breast cancer survivors, especially those treated with chemotherapy, are likely to gain weight at a higher rate than women who are cancer-free, says a new research.

Data from earlier studies suggest that breast cancer survivors who gain weight may have a higher risk of having their cancer return, researchers said.

"Our study suggests that chemotherapy may be one of the factors contributing to weight gain among survivors," said Kala Visvanathan, associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health in the US.

The results of the study that involved 303 breast cancer survivors and 307 cancer-free women appeared online in the journal Cancer Epidemiology, Biomarkers & Prevention.

The researchers found that over the course of four years, survivors gained significantly more weight -- 3.6 pounds (1.6 kg) on average -- than cancer-free women.

Among 180 survivors diagnosed with cancer during the last five years of the study period, 37 (21 percent) gained at least 11 pounds (five kg) over a four-year period compared with 35 of 307 (11 percent) of their cancer-free peers.

The weight-change findings remained the same after accounting for other factors associated with weight gain, such as increasing age, transition to menopause and level of physical activity, researchers said.

Women who completed chemotherapy within five years of the study were twice as likely as cancer-free women to have gained at least 11 pounds during the study.