BOSTON—Elderly women with early-stage breast cancer who receive radiotherapy after lumpectomy have better outcomes than those treated with surgery alone, according to two large studies presented here at the American Society for Radiation Oncology Annual Meeting.
Both studies utilized Surveillance, Epidemiology, and End Results (SEER) database records; one involved 29,949 patients aged 70 to 84 at diagnosis (Abstract 82), and the other (Abstract 84) included 27,559 women age 70 and over.
In both studies, women treated with both modalities had higher overall and breast cancer–specific survival rates compared with women who received lumpectomy alone.
Commenting on the studies, though, Bruce G. Haffty, MD, Chair of Radiation Oncology at Robert Wood Johnson Medical School of the University of Medicine and Dentistry of New Jersey, cautioned that although large database studies are useful for allowing researchers to see trends that might otherwise go unnoticed, treatment cannot be guided by such studies: “We have to decide on an individual basis which option is best for individual patients, given all the risks and benefits.”
The principal investigator of the first study, Randi J. Cohen, MD, Assistant Professor of Radiation Oncology at the University of Maryland, said, “The improvement in breast-cancer survival with the addition of radiation suggests that in healthy, elderly women, adjuvant radiation should be strongly considered as part of their breast cancer treatment.”
About 76 percent of the women in that study received radiation, and its use dropped with increasing age. The overall survival rate for women treated with lumpectomy and radiation was about 89 percent at five years and 65 percent at 10 years. In contrast, five- and 10-year survival rates were approximately 73 and 42 percent, respectively, for those who did not receive radiation. “The differences were highly statistically significant at both time points,” she said.
The cause-specific survival rates at five years were 98 percent in the radiation-plus-surgery group versus 97 percent for those in the no-radiation group. At 10 years, the rates were 95.5 percent and 93 percent, respectively. Again the differences were statistically significant.
“Women who received radiation are likely to be healthier, so cause-specific survival is a more important endpoint in that sense,” Cohen said.
The median survival was 13.1 years in the radiation group vs. 11.1 years in the no-radiation group.
The second study had similar results, with five- and eight-year survival rates of 87 and 73 percent, respectively, in the radiation arm. In contrast, the rates were only 68 and 50 percent in the lumpectomy-only arm, reported Mariam P. Korah, MD, Assistant Professor of Radiation Oncology at the University of Southern California Keck School of Medicine.
Radiation was also shown to improve cause-specific survival rates, which were 97 and 95 percent for patients who received radiation at the five- and eight-year follow-up points, compared with 95 and 91 percent for those who did not.
A total of 4,573 deaths were recorded, 17 percent (790) of which were attributed to breast cancer.
The findings contrast, though, with the results of the Cancer and Leukemia Group B 9343 study (NEJM 2004; 351:971–977), which found a two to three percent difference in the rates of breast recurrence but no difference in the rates of mastectomy or distant disease-free or overall survival.
That study led to a revision in 2005 of the National Comprehensive Cancer Network (NCCN) guidelines, which now state that breast irradiation may be omitted in patients age 70 and older who have estrogen-receptor positive, clinically node-negative T1 tumors and who receive adjuvant endocrine therapy.
“The proportion of patients receiving radiation therapy declined by 5.5 percent from 2005 to 2009, after the NCCN guidelines were published,” Korah noted. “Moving forward, treatment recommendations should be guided by a synthesis of best available aggregate evidence.”