e23018 Background: As the treatment for early-stage breast cancer continually evolves, there has been a pragmatic shift with regard to standard treatment placing a high-value on multidisciplinary management. Recent studies have shown that sentinel lymph node biopsy (SLNB) and adjuvant radiation (RT) can be omitted in a subset of older women with early-stage hormone receptor positive breast cancer who plan to take adjuvant endocrine therapy (ET). Prior analyses estimate a wide range of discontinuation rates, with studies citing 31-73%. The primary aim of this analysis is to estimate the discontinuation rate of endocrine therapy in women ages 70 and older with early stage breast cancer who omit radiation therapy at our institution. Methods: We performed a retrospective review of institutional cancer registry and EMR data to identify all women with breast cancer, ages 70 or older, AJCC 7 stage I or II, hormone receptor positive, HER2 negative, who underwent lumpectomy at the University of Michigan inclusive of years 2014 through 2017. Multiple variables of interest were collected and analyzed. Results: 174 women met initial inclusion criteria for ER/PR positive, HER2 negative, Stage I/II disease, who underwent lumpectomy. Of these, N = 10 pursued adjuvant radiation therapy with omission of ET, and N = 19 declined both ET and RT upfront. The remaining 145 women chose to pursue ET alone (N = 78) or ET+RT (N = 67). 30/145 (21%) discontinued endocrine therapy, 22% (N = 15) in the ET+RT, 19% (N = 15) in the ET alone groups. There was no statistically significant difference between groups with regard to the discontinuation of ET upon comparison, log-rank p-value 0.4. The primary reason for ET discontinuation, N = 27 (90%) was secondary to side effects. Conclusions: This review demonstrated that a significant number (54%) of older women opt to omit radiation in favor of ET alone after multidisciplinary discussion, in accordance with NCCN guidelines. Endocrine therapy discontinuation rates among older women at our institution were comparable to rates in the literature for women of all ages, and the reason for discontinuation was attributed to side effects. The pivotal clinical trials (PRIME II and CALGB 9343) exploring ET alone versus ET+RT did not report on ET discontinuation rates. In our analysis, almost 20% of women receiving ET alone discontinued ET therapy, calling into question a missed radiation treatment opportunity in a curative setting.
Erratum to: Wang SY, Kelly G, Gross C, et al. Information needs of older women with early-stage breast cancer when making radiation therapy decisions. Int J Radiat Oncol Biol Phys 2017;98:733-740.