A. C. Esposito1, J. L. Crawford2, E. R. Sigurdson2, E. Handorf4, R. J. Bleicher2 1Lewis Katz School Of Medicine At Temple University,Philadelphia, PA, USA 2Fox Chase Cancer Center,Surgical Oncology,Philadelpha, PA, USA 4Fox Chase Cancer Center,Biostatistics,Philadelphia, PA, USA
Introduction:
Breast conservation has been standard of care for invasive breast cancer, and complete treatment via breast conservation therapy (BCT) is comprised of both breast conservation surgery and radiotherapy (RT). Neoadjuvant chemotherapy (NACT) is given to make tumors having skin or chest wall involvement resectable, and to downstage those too large for local excision to a size amenable to BCT. On reviewing patterns of postneoadjuvant RT administration in the National Cancer Database (NCDB), we found that significant numbers of BCT patients did not receive RT after NACT. This study was performed to determine what factors predicted RT omission, which is nonstandard therapy.
Methods:
NCDB cases were reviewed for women having unilateral, invasive, non-inflammatory, non-metastatic, clinical stage 2-3 breast cancer, treated with NACT and subsequent BCT between 2008-2012. Only those starting NACT <90 days after diagnosis but 80-270 days preoperatively, and RT 0-20 weeks post-op were included. We used Pearson Chi-square and tests for trend to determine the relationship between patient, tumor, and facility factors and receipt of RT. We then determined simultaneous effects of these factors using multiple logistic regression with robust standard errors to account for within-hospital clustering.
Results:
10,220 patients were identified who received NACT prior to breast conservation with 974 (9.53%) not receiving RT after surgery. The majority of patients were white, female, had invasive ductal carcinoma, and received therapy at comprehensive community cancer centers or academic/research programs. Predictors of failure to receive RT included older age (ORs 1.17; 95% CI: 1.09-1.27, P=<.0001), more recent year of diagnosis (OR 1.06; 95% CI: 1.01-1.12, P=.0267), US region (ORs varied), insurance status (ORs varied), facility type (ORs 1.48; 95% CI: 1.02-2.16, P=.0404), positive margins (ORs 1.67; 95% CI: 1.29-2.16, P=.0001), receptor status unknown (OR 1.68; 95% CI: 1.19-2.37, P=.003), and HER2 status positive or unknown (ORs varied). Factors increasing the likelihood of RT receipt included N3 disease (ORs 0.59; 95% CI: 0.36-0.95, P=.0312), known grade (ORs varied), primary tumor downstaging (ORs 0.84; 95% CI: 0.72-0.98, P=.024), and receptor positivity (ORs 0.85; 95% CI: 0.73-0.99, P=.0391). Factors having no effect on likelihood of RT included race, education, income, and Charlson comorbidity index. When excluding 314 patients in whom RT was recommended, only age, US location, receptor status, and margins remain predictors.
Conclusion:
It is encouraging that racial and socioeconomic disparities were not found among the predictors for lack of RT receipt. Unfortunately however, comorbidities did not explain the difference in treatment. It remains unclear whether some omission of RT is due to lack of physician knowledge. Further efforts may be needed to ensure that physicians and patients recognize that RT is a required part of BCT even after NACT.