Women who receive radiotherapy for rectal cancer may be at an increased risk of uterine and ovarian cancer, a US study suggests.

In an analysis of information from the Surveillance, Epidemiology and End Results (SEER) database on more than 20,000 US female patients diagnosed with rectal cancer, researchers found the treatment was associated with a three-fold increased risk of subsequent uterine cancer and a two-fold increased risk of ovarian cancer.

Chinese researchers used information from SEER from 1973 to 2015, including women aged 20 or older diagnosed with either rectal cancer or rectosigmoid cancer and recorded the incidence of gynaecological malignancies occurring five years or longer after radiotherapy.

Some 15,000 of the women received surgery alone while more than 5000 received surgery plus radiotherapy. Median follow-up was nearly 12 years.