The influence of radiation therapy on survival among Medicaid-enrolled breast cancer patients treated with breast conserving surgery

Abstract

609 Background: A growing body of evidence indicates that breast cancer patients treated with breast conserving surgery (BCS) without radiotherapy (RT) have a greater risk of cancer recurrence and mortality compared to those receiving BCS plus RT. Most of the research to date has not included or accounted for women with lower socioeconomic status. Methods: Using cancer registry, Medicaid claims, and Social Security death index data, we evaluated receipt of RT and mean 6-year overall and cancer-specific survival among Medicaid-enrolled breast cancer patients treated with BCS (n=230). Logistic regression was used to assess predictors of RT. The Kaplan-Meier method was used to determine survival by RT status and a multivariate Cox proportional hazards regression model was used to evaluate the role of RT on overall and cause-specific survival while controlling for demographic, clinical, and comorbid factors. Results: 65% of women received RT. Overall, 82% of the sample survived the 5–6 year study period, with death rates of 16% compared to 51% among those who did and did not receive RT, respectively (p<.001). Among the 24 individuals who died from cancer, 8 (33.3%) received radiation and 16 (66.7%) had not. After controlling for demographics, clinical factors, and comorbidity, use of RT was associated with a statistically significant decrease in all-cause mortality (hazard ratio = 0.42, 95% CI 0.21–0.85) and cancer-specific mortality (hazard ratio = 0.22, 95% CI −0.09–0.57). Conclusions: We found under-use of radiation following BCS in this Medicaid-enrolled population of breast cancer patients. Furthermore, omission of RT was associated with a greater than two-fold increased risk of death and almost a five-fold increase in cancer-specific death. Measures to improve RT use among poor women receiving BCS need to be implemented. No significant financial relationships to disclose.