Treatment effect of neoadjuvant endocrine therapy compared to neoadjuvant chemotherapy on breast cancer outcomes.

e12630Background: Over the last decade, there has been increased use of neoadjuvant endocrine therapy (NET) for the treatment of hormone receptor (HR) positive breast cancer. Small clinical trials have demonstrated that for certain patients, NET is associated with similar rates of both complete response (CR) and similar rates of breast conservation surgery (BCS) compared to neoadjuvant chemotherapy (NAC). We aimed to compare the effectiveness of NET versus NAC with regards to complete pathologic response (pCR), change in stage, and breast conservation Methods: We performed a population-based assessment using the National Cancer Data Base to identify women diagnosed with stage II-III, HR-positive BC who received NET or NAC from 2004 through 2014 and subsequently underwent surgery. We ran logistic regression models to assess differences in outcomes between therapies, with inverse probability of treatment weighting using the propensity score to adjust for potential selection bias. Results: In our sample of 5...