Radiation therapy after breast-conserving surgery may help prevent a future mastectomy for the majority of older, early-stage breast cancer patients, according to a study conducted by researchers at The University of Texas MD Anderson Cancer Center and published in the journal Cancer.
The findings are contrary to current national treatment guidelines, which forgo radiation therapy postsurgery and instead recommend that older women with early-stage, estrogen-positive breast cancer be treated with lumpectomy followed by estrogen blocker therapy alone.
According to a major study in 2004, women who received treatment with tamoxifen only had a slightly higher incidence of breast cancer recurrence compared with women who received tamoxifen and 6 weeks of radiation. Yet, mastectomy rates and survival remained the same between the 2 groups, said Benjamin Smith, MD, assistant professor in the Department of Radiation Therapy at MD Anderson and the study’s corresponding author.
“The motivation for this new research was to do a similarly designed study with longer-term follow-up,” said Smith. “We wanted to do a 10-year update, focusing specifically on the mastectomy question. The fundamental reason it was determined that women didn’t need radiation was because the additional therapy did not change mastectomy rates.”
For the population-based study, researchers obtained data from a group of Medicare patients from the National Cancer Institute’s Surveillance, Epidemiology, and End Results registry who would have been eligible for the 2004 study. A total of 7403 patients between the ages of 70 and 79 were identified. All were diagnosed between 1992 and 2002, underwent lumpectomy for early-stage estrogen-positive breast cancer, and were followed through 2007. Of the 7403 women, 88% received radiation after their lumpectomy.
Within 10 years of treatment, 6.3% of the women who received only tamoxifen had a mastectomy. Smith says this is likely due to a breast cancer recurrence. Only 3.2% of the women who had the additional radiation treatment had a mastectomy. Furthermore, radiation seemed to be highly beneficial in patients with high-grade tumors, regardless of other factors (age and/or tumor characteristics).
According to Smith and his colleagues, 1 subset of women did not benefit from radiation: those aged 75 to 79 years who had their lymph nodes assessed and did not have high-grade tumors.
“Our study … provides data that physicians can use when talking to their patients about whether to go forward with radiation,” said Smith.