ISLAMABAD: Women with breast cancer who received radiation through strategically placed “seeds” had double the risk of a mastectomy later on, compared with women who got radiation for their entire breast, new research finds.

This type of targeted radiation, known as brachytherapy, also resulted in more side effects, including infection, according to the study.

“We were very surprised by the results,” said Dr. Benjamin Smith, senior author of the study, which is being presented Wednesday at the 2011 San Antonio Breast Cancer Symposium.

“Our data suggests that some of the trade-offs between brachytherapy and whole breast irradiation, at least on the average across the country, might be a little bit more complex than may have initially been appreciated,” added Smith, who is an assistant professor of radiation oncology at M.D. Anderson Cancer Center in Houston.

Already used successfully for some men with prostate cancer, brachytherapy is also gaining currency for older women with breast cancer.This has occurred even though few studies have done head-to-head comparisons of brachytherapy and traditional whole breast irradiation, the researchers noted.

The study authors looked at Medicare records of more than 130,500 women older than 66 who were treated first with a lumpectomy then with either brachytherapy or whole breast irradiation.

As an indication of the targeted therapy’s rising popularity, the authors said that less than 1 percent of the women in the group underwent brachytherapy in 2000, compared to 13 percent in 2007.