Chemotherapy use for hormone receptor-positive, node-negative breast cancer

11004 Background: High quality evidence has shown that adjuvant chemotherapy (chemo) improves survival for hormone receptor- positive, node negative breast cancer measuring >1 cm (H+/N-/T>1cm BC). Since 2002 National Comprehensive Cancer Network (NCCN) guidelines have recommended chemo for this group. Because the benefit from chemo in this situation is modest there is debate regarding which women, if any, can forego chemo. We describe trends in chemo use and identify factors associated with not receiving chemo for H+/N-/T>1cm BC. Methods: We identified women less than 70 years old with H+/N-/T>1cm BC diagnosed 1997–2004 and treated at 8 NCCN institutions. We analyzed the frequency of chemo use on a yearly basis (chi square). A multivariable logistic regression model assessed the relationship between likelihood of not receiving chemo and year of diagnosis, institution, tumor size, histologic characteristics and socio- demographic variables. We incorporated interaction terms to explore how chemo use varied over time and between institutions. Results: Of 3190 women with H+/N-/T>1cm BC, 56% received chemo. Chemo use was less common for 1.1–2 cm than for >2 cm tumors (48 vs. 83%; p<.01). There was no significant change in chemo use over time, but there was significant variability among institutions (range 47–65%; p<.01). On multivariable analysis, predictors independently associated with not receiving chemo included lower histologic/nuclear grade, non-ductal/lobular histology, absence of lymphovascular invasion or HER2 overexpression, and older age (p<.01 for all). The interaction between institution and year of diagnosis was also significant (p<.01). Over the 2 years following the NCCN guideline’s definitive recommendation for chemo in 2002, the relative change in institutional chemo use ranged from a 25% decrease to a 28% increase. Conclusions: Many women did not receive chemo despite clinical trial evidence. Providers considered molecular features, tumor size and patient age when deciding who should receive chemo. While overall trends in chemo use did not change, use appeared to increase at some institutions and decreased at others after the 2002 guideline recommendation for chemo. This suggests a lack of consensus at NCCN institutions regarding when to administer chemo for H+/N-/T>1cm BC. No significant financial relationships to disclose.