Guideline-concordant treatment predicts survival: a National Cancer Database validation study of novel composite locoregional and systemic treatment scores among women with early stage breast cancer.

BACKGROUND: The aim of this large nationwide study was to validate two novel composite treatment scores that address guideline-concordant locoregional and systemic breast cancer care. We examined the relationship between these two scores and their association with survival.
METHODS: Women with Stage I-III unilateral breast cancer were identified within the National Cancer Database. For each woman, a locoregional and a systemic treatment score (0, 1, 2) was assigned based on receipt of guideline-concordant care. Multivariable Cox regression models evaluated the association between the scores and survival.
RESULTS: 623,756 women were treated at 1,221 different American College of Surgeons Commission on Cancer (CoC) facilities. Overall, 86% had a locoregional treatment score of 2 (most guideline-concordant), 75% had a systemic treatment score of 2, and 72% had both scores of 2. Median follow-up was 4.5 years. Compared to women with a locoregional treatment score of 2, those with a score of 1 or 0 had a 1.7-fold and 2.0-fold adjusted greater risk of death. Compared to women with a systemic treatment score of 2, those with a score of 1 or 0 had a 1.5-fold and 2.1-fold adjusted greater risk of death. Risk-adjusted 5-year overall survival was 91.6% when both scores were 2 compared to 73.4% when both scores were 0.
CONCLUSIONS: In this large national study of CoC facilities, two composite scores capturing guideline-concordant breast cancer care had independent and combined robust effects on survival. These clinically constructed novel scores are promising tools for health services research and quality-of-care studies.