Women with breast cancer who receive radiation after surgery are half as likely to have their disease return within 10 years and are one-sixth less likely to die over a 15-year period, according to the results of a new study reported Friday.
Experts say the findings of the latest study of the disease underline the need to improve radiotherapy provision.
An analysis that crunched together the results from nearly 11,000 women who participated in 17 previous trials worldwide -- making it by far the biggest study so far on this topic -- found that a decade after a breast cancer diagnosis, 35 percent of the women who did not have radiotherapy had their cancer return, compared with 19 percent of those who did get the treatment.
Even though radiation is usually given after breast-conserving surgery to kill any cancer cells that escaped the surgeon's knife and to prevent local recurrence, the findings also suggest radiotherapy has a benefit in reducing the risk of the cancer spreading elsewhere in the body.
Fifteen years after the diagnosis, 25 percent of the women who did not have radiation treatment following surgery had died from breast cancer, compared with 21 percent who did.
The findings -- published by The Lancet and compiled by experts from the University of Oxford-based Early Breast Cancer Trialists' Collaborative Group with funding from Cancer Research UK, the British Heart Foundation and Britain's Medical Research Council -- have been welcomed by cancer experts.
Cancer Council Australia chief executive Ian Olver said the previous assumption had been that the role of radiotherapy was "really to sterilize the rest of the breast after breast-conserving surgery."
"You would expect it to decrease local recurrence, but what this study shows is that 15 years on, it's improving survival as well," Olver said. "The radiotherapy is helping to protect women from widespread and metastatic disease."