Disparities in the application of adjuvant radiotherapy after breast-conserving surgery for early stage breast cancer: impact on overall survival.

BACKGROUND: Definitive local therapy of early stage breast cancer includes adjuvant radiotherapy after breast-conserving surgery (BCS). The authors analyzed factors that influence the receipt of radiotherapy therapy and their resultant impact on outcome.
METHODS: Using data from the Kentucky Cancer Registry, the authors analyzed the rate of adjuvant radiotherapy for 11,914 women who underwent BCS as a primary surgical treatment for stage 0, I, or II breast cancer between 1998 and 2007. The authors assessed the probability of receiving radiotherapy by using multivariate logistic regression and measured impact on outcome by using Cox survival analysis.
RESULTS: Overall, 66.2% of women received adjuvant radiotherapy for BCS over a 10-year period (annual rate range, 60.9%-70.1%). On multivariate analysis, the rate of receiving radiotherapy was drastically lower for women aged older than 70 years (vs younger) and rural Appalachian (vs non-Appalachian) populations. The rate was modestly lower for African American (vs white) women, those with in situ (vs invasive) disease, and uninsured (vs insured) patients. Lack of radiotherapy was associated with an increased hazard ratio for death of 1.67 (95% CI, 1.508-1.851) on Cox survival analysis when age, stage, tumor size, grade, hormone receptors, smoking, and insurance were factored into the analysis. The 10-year overall survival for patients who received adjuvant radiotherapy versus BCS alone was 79.7% versus 67.6% (P < .0001).
CONCLUSIONS: Despite widespread knowledge of the benefit of RT after BCS, the rate of undertreatment remains high, with significant disparities for elderly, rural, minority, and uninsured women. Multidisciplinary management strategies, including accelerated and hypofractionated radiation regimens, are needed to eliminate disparities and improve outcomes.