Survival disadvantage among Medicaid-insured breast cancer patients treated with breast conserving surgery without radiation therapy.

BACKGROUND: Clinical studies indicate that breast cancer patients treated with breast conserving surgery (BCS) without radiotherapy (RT) have a greater risk of recurrence and mortality compared to those receiving BCS plus RT. However, this relationship has been underdeveloped among low-income women in the community who may face barriers in accessing adjuvant treatment and post-treatment surveillance. It is possible that the prognostic significance of omission of RT in clinical trials underestimates the significance of risk in the community.
METHODS: Using cancer registry, Medicaid claims, and the Social Security Master Death File, we evaluated receipt of RT in women with early stage breast cancer treated with BCS and mean 6-year overall and cancer-specific survival. Logistic regression was used to assess correlates of RT. The Kaplan-Meier method was used to determine survival by RT status and a multivariate Cox proportional hazards regression was used to evaluate the role of RT status on overall and cause-specific survival.
RESULTS: A total of 65% of women received RT, and 82% of the sample survived the study period. Death rates of 16% and 51% were observed among those who did and did not receive RT, respectively (P < 0.001). One-third of women who died from cancer (8 of 24) received radiation. Use of RT was associated with a statistically significant decrease in all-cause (hazard ratio = 0.42, 95% CI 0.21-0.85) and cancer-specific mortality (hazard ratio = 0.22, 95% CI -0.09 to 0.57).
CONCLUSIONS: Adjuvant radiation following BCS was underused in this sample of poor breast cancer patients. Lack of adjuvant RT may be a proxy for inadequate access to care and poor cancer surveillance after treatment.