To examine local definitive therapy for non-metastatic breast cancer using the Centers for Disease Control and Prevention’s National Program of Cancer Registries Patterns of Care Breast and Prostate Cancer (POCBP) study.

POCBP medical record data were re-abstracted in seven state/ regional registry systems (GA, NC, KY, LA, WI, MN and CA) to verify data quality and assess treatment patterns in the population. National Comprehensive Cancer Network clinical practice treatment guidelines were aligned with American Joint Committee on Cancer stage at diagnosis to appraise care.

6,505 of 9142 patients with registry confirmed breast cancer were coded as primary disease with 0-IIIA stage tumors and were included for study. Approximately 90% received guideline concordant loco-regional treatment; however this outcome varied by age group as 92.9% of women < 65 years and 85.2% ≥ 65 years received standard care (p <0.0001). Characteristics which best discriminated receipt of guideline concordant care in receiver operating curve (ROC) analyses (C-value) were receipt of BCS versus mastectomy (C = 0.70), patient age (C=0.62), greater tumor stage (C= 0.60), public insurance (C= 0.58) and presence of at least mild comorbidity (C = 0.55). RT following BCS was the most omitted treatment component causing non-concordance in the study population. In multivariable regression, effects of treatment facility, DCIS, race, and comorbidity on non-concordant care differed by age group.

Patterns of underuse of standard therapies for breast cancer vary by age group and BCS use, where omission of RT is at risk.