A. Nayyar1, K. K. Gallagher1, P. D. Strassle1, C. G. Moses1, K. P. McGuire2 1University Of North Carolina At Chapel Hill,Department Of Surgery,Chapel Hill, NC, USA 2Virginia Commonwealth University,Department Of Surgery,Richmond, VA, USA
Introduction:
Women ≥70 years old form a significant proportion of patients affected by breast cancer (BC). Treatment decisions for this patient population are complicated given presence of comorbidities, reduced tolerability of therapy and limited enrollment in clinical trials. A growing body of evidence suggests equivalent outcomes in elderly patients with hormone receptor positive, early-stage BC patients receiving primary endocrine therapy only or surgery with subsequent endocrine therapy. Whether these results are reproduced in the larger BC population outside of a clinical trial, currently remains unclear.
Methods:
Women ≥70 years old, diagnosed with early-stage invasive BC between January 2008 and December 2013, with tumor size T1 or T2 and minimal nodal involvement (N0 and N1), endocrine and/or progesterone receptor positive, and started endocrine therapy within a year of diagnosis were identified using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked datasets. Endocrine therapy use was identified using outpatient prescription fills for Anastrozole, Exemestane, Fulvestrant, Letrozole, Raloxifene, Tamoxifen, and Toremifene. Surgical intervention included either breast conserving surgery or mastectomy. Trends in the use of primary endocrine therapy only were assessed using Poisson regression. Multivariable Cox proportional hazard regression was used to estimate the association between undergoing surgery within a year of diagnosis and 5-year all-cause mortality, after adjusting for patient demographics, comorbidities, and clinical cancer characteristics. Similar methods were used to assess 5-year cancer-specific mortality, where non-cancer mortality was treated as a competing risk.
Results:
Overall, 8,968 women were included in the analysis; 8,146 (91%) received surgery with endocrine therapy and 832 (9%) received primary endocrine therapy alone. The proportion of women not receiving surgery remained consistent between 2008 and 2013, p=0.24. The 5-year mortality was 7% (n=660), and 21% of all deaths were due to cancer causes (n=140). After adjustment, 5-year mortality was lower among women undergoing surgery (HR 0.55, 95% CI 0.44, 0.67, p<0.0001) (Figure). Similar results were found when looking at 5-year cancer-specific mortality (HR 0.35, 95% CI 0.22, 0.56, p<0.0001).
Conclusion:
Elderly BC patients with early-stage, hormone receptor positive disease receiving primary surgical intervention plus endocrine therapy had improved survival compared to those receiving primary endocrine therapy alone. This study reflects the importance of surgical intervention for elderly BC patients and warrants further investigation to evaluate whether surgery may be omitted safely in subsets of elderly patients.
