By Serena Gordon
FRIDAY, April 26, 2019 (HealthDay News) -- For women with hormone-driven breast cancer, adding radiation to hormone therapy might keep their cancer from coming back for up to a decade, a new study finds.
Breast cancer didn't come back in the same breast for 97.5% of women who had radiation therapy plus hormone therapy compared to just over 92% of women who had hormone therapy alone, the researchers said.
In addition, over the study's 10-year follow-up period, 94.5% of the women in the radiation therapy group were still alive without a cancer recurrence, compared to just over 88% of women who only had hormone therapy.
Study author Dr. Gerd Fastner, from Paracelsus Medical University in Salzburg, Austria, said the study shows that adding radiation therapy can increase disease-free survival and improve the odds a cancer won't come back over the long term.
Dr. Alice Police, regional director of breast surgery at Northwell Health Breast Care Centers Westchester in Sleepy Hollow, N.Y., said the findings are important because "there have been a lot of studies trying to prove that in small cancers in postmenopausal women, there may be a group of women who can skip radiation. This study shows it's still not safe to omit radiation therapy in women who have had breast-conserving surgery."
Police added that while women with these specific cancers might think they can choose one treatment or another, a combination yields the best results.
The study included nearly 900 postmenopausal women. Fastner said they were between 46 and 80 years old, with an average age of 66. All of the women were from Austria, and most were white.
The women in the study all had breast cancer that was considered low risk for spreading. Their tumors were small in size (under 3 centimeters).
All of the women had breast-conserving surgery. That means rather than removing the entire breast (mastectomy), surgeons remove the tumor and a bit of the healthy tissue around the tumor.
The study patients all had hormone receptor-positive cancers, which means that hormones such as estrogen and progesterone fueled the cancer's growth, according to the U.S. National Cancer Institute. About two of three breast cancers are hormone receptor-positive, according to the American Cancer Society.
After surgery, the women in the study were all treated with hormone therapies such as tamoxifen or anastrozole. These therapies either remove hormones or block their action, according to the cancer institute.
Some women -- 439 -- received radiation therapy for just over a month within six weeks of their surgery. The remaining 430 women took hormone therapy alone.
A decade later, 10 women in the radiation group had a recurrence of cancer in the same breast. In the hormone therapy-only group, 31 women had a cancer recurrence, the researchers found.
The findings are to be presented Sunday at the European Society for Radiotherapy and Oncology (ESTRO) meeting, in Milan. Findings presented at meetings are typically viewed as preliminary until they've been published in a peer-reviewed journal.
Fastner said it's still a matter of some debate if all women with these low-risk cancers should be given radiation therapy after breast-conserving surgery, largely because of newer techniques, such as partial breast radiation and brachytherapy.
And, in a small, select group of women, it might be better to forgo radiation.
"The total omission of radiotherapy should only be considered in frail, elderly patients who would not be able to tolerate such treatment," Fastner said in a meeting news release.
Funding for the study was provided by Astra Zeneca, a pharmaceutical company that produces hormone therapies.