Obesity and guideline-concordant systemic therapy for locoregional breast cancer.

145 Background: Obese breast cancer patients tend to have higher mortality than non-obese patients. Hypothesizing that differences in receipt of adequate treatment may contribute to this mortality differential, we examined whether breast cancer patients with higher body mass index (BMI) received systemic adjuvant treatment consistent with National Comprehensive Cancer Network guidelines. METHODS: Female adult stage I-III breast cancer cases diagnosed in 2004 were identified from population-based cancer registries in 7 states and supplemented with abstracted medical records. Differences in receipt of concordant treatment according to BMI were investigated using logistic regression models adjusted for age and other covariates. RESULTS: Among all women, 57% (2,174 of 3,828) received overall guideline-concordant (GC) adjuvant systemic treatment, meaning treatment adherent in each of 3 defined domains: chemotherapy, chemotherapy regimen, and hormonal therapy. Within the domains, 82% of women received GC chemotherapy, and 93% of those received a GC regimen, and 80% received GC hormonal therapy. Women with higher BMI had greater odds of receiving GC systemic therapy (odds ratio for each 5 kg/m(2) increase in BMI 1.07, 95% CI 1.01 to 1.14; p value for trend = 0.04). No significant differences in guideline treatment according to BMI were found in the individual therapy domains (adjuvant chemotherapy, p = 0.18; chemotherapy regimen, p = 0.26), although a borderline significant, nonlinear pattern was seen for hormonal therapy, in which the highest odds of GC treatment were found in the lowest and highest BMI ranges (p = 0.07 from χ(2) test). CONCLUSIONS: Contrary to our hypothesis, odds of guideline concordant systemic therapy increased with higher BMI, and no significant differences were found within any specific treatment domain. Further research describing how multiple factors including treatment patterns influence outcomes for obese breast cancer patients may identify areas where changes in practice can reduce disease burden and mortality. Our research also suggests further investigation into patterns of care for underweight patients.

Duke Scholars

Author Gretchen Genevieve Kimmick Medicine, Medical Oncology