May 19, 2016
December 2012, Vol 1, No 6
Two Studies Show That Radiation Extends Survival in Elderly Women With Early-Stage Breast Cancer
UncategorizedRadiation therapy extends life in older women with early-stage breast cancer, according to 2 studies presented at the 54th Annual Meeting of ASTRO.
The first study showed that the addition of radiation to lumpectomy improved overall survival (OS) as well as cause-specific survival (CSS) in women aged 70 or older.
The study population included 29,949 women identified in a SEER Medicare database who were diagnosed with stage I, estrogen receptor–positive (ER+) breast cancer. All women underwent lumpectomy with or without adjuvant radiation and survived at least 1 year after the initial diagnosis. Seventy-six percent received adjuvant radiation therapy.
Median survival was 13.1 years for women treated with surgery plus radiation and 11.1 years for those treated with surgery alone. Five-year CSS was 98.3% for the adjuvant radiation group versus 97.6% for the surgery-alone group. Ten-year CSS was 95.4% versus 93.3%, respectively; 15-year CSS was 91.4% versus 89.5%, respectively.
At all time points, the use of adjuvant radiation improved OS. At 5 years, OS was 88.6% for those who received radiation versus 73.1% for the surgery-alone arm (P<.0001); at 10 years, OS was 65% versus 41.7%, respectively (P<.0001); at 15 years, OS was 39.6% versus 20%, respectively.
A related study based on 27,559 patients from a SEER Medicare database found that older women with early-stage, low-risk breast cancer treated with radiation after breast-conserving surgery (BCS) had superior CSS and OS rates compared with women who did not undergo radiation after BCS. The study showed a 6% decline in use of radiation after 2004, coinciding with revised National Comprehensive Cancer Network guidelines allowing omission of radiation therapy as a reasonable option for women over age 70 with small ER+ tumors treated with adjuvant tamoxifen.
CSS favored radiotherapy. At 5 years, CSS was 97% for those who received radiotherapy versus 95% for those who did not, an absolute difference of 2%; by 10 years, the absolute difference was doubled to 4%, favoring radiation: 95% and 91%, respectively.
OS also favored the addition of radiotherapy to surgery. Five-year OS was 87% versus 68%, respectively, with an absolute difference of 19% favoring radiation, and 8-year OS was 73% versus 50%, respectively, for an absolute difference of 23% favoring radiation.
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