Adjuvant radiation and outcomes after breast conserving surgery in publicly insured patients

ObjectivesEpidemiologic studies report that lack of adjuvant radiation (RT) after breast conserving surgery (BCS) is associated with higher short-term mortality. It is generally accepted that adjuvant RT decreases risk of breast cancer recurrence and thereby lowers long-term mortality; here, we explore reasons for its relationship to short-term mortality.Materials and MethodsWe studied 1583 publically insured women who had BCS between 1998 and 2002 (mean 71.8 years, range 27–101), of whom 1346 (85%) received RT. Multivariate analyses with Cox Proportional Hazards and Logistic Regression models included: age; race; comorbidity; insurance status; tumor size; number of nodes positive; hormone receptor status; receipt of radiation; adjuvant chemotherapy; preventive care — including mammography, Pap smear and primary care visits; and hospitalization.ResultsAt a mean follow-up of 52.8 months, overall mortality was significantly lower in those who received RT (HR 0.45, p < 0.0001) and higher with older age (HR 1.05, p < 0.0001) and greater comorbidity (HR 1.16, p = 0.0007). Local recurrence was less with receipt of optimal radiation (HR 0.47; p = 0.03). Breast cancer event, as determined by a clinically logical algorithm to detect breast cancer recurrence and death, however, was not significantly associated with receipt of RT (OR 1.32, p = 0.2).ConclusionThese results imply that the higher short-term mortality in women not receiving RT after BCS is related to factors other than breast cancer recurrence.