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.
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.
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).
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.