Radiation Therapy After Breast-Conserving Surgery in Women 70 Years of Age and Older: How Wisely Do We Choose?

BACKGROUND: Despite data from randomized trials supporting omission of radiation therapy (RT) for women ≥ 70 years of age with T1, estrogen receptor-positive (ER+) tumors undergoing breast-conserving therapy (BCT), RT usage remains high. We reviewed our institutional experience to determine if risk factors for local recurrence or comorbidities influenced use.
METHODS: Women ≥ 70 years of age with T1, ER+, human epidermal growth factor receptor 2-negative (HER2-) tumors undergoing BCT in 2010-2012 were identified from a prospectively maintained database. Ten-year estimated mortality was calculated using the Suemoto index. The associations of clinicopathological features and mortality risk on receipt of RT were examined.
RESULTS: Overall, 323 patients with 327 cancers were identified. Median age was 75 years, median tumor size was 1 cm, and all were clinically node negative; 53.7% of patients received RT. RT usage decreased with age (73.6%, age 70-74 years; 49.5%, age 75-79 years; 33.3%, age 80-84 years; 10.7%, ≥ 85 years; p < 0.001). Within age groups, estimated mortality did not impact RT usage. On multivariable analysis, only younger age and larger tumor size were associated with RT use. Recurrence-free survival was 98% versus 93% with and without RT, respectively (p = 0.011). Those who received adjuvant radiation also had improved overall survival (92% vs. 89%), although this effect did not reach statistical significance (p = 0.051).
CONCLUSION: Neither the factors associated with risk of local recurrence nor the estimated risk of death in 10 years were associated with use of adjuvant radiation in a large cohort of women ≥ 70 years of age with small ER+ breast cancers treated with breast-conserving surgery.