Delay in initiating adjuvant radiotherapy following breast conservation surgery and its impact on survival

Purpose: Delays in the diagnosis of breast cancer are associated with advanced stage and poor survival, but the importance of the time interval between lumpectomy and initiation of radiation therapy (RT) has not been well studied. We investigated factors that influence the time interval between lumpectomy and RT, and the association between that interval and survival. Patients and Methods: We used data from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database on women aged 65 years and older, diagnosed with Stages I-II breast cancer, between 1991 and 1999. Among patients who did not receive chemotherapy, we studied factors associated with the time interval between lumpectomy and the initiation of RT, and the association of delay with survival, using linear regression and Cox proportional hazards modeling. Results: Among 24,833 women with who underwent lumpectomy, 13,907 (56%) underwent RT. Among those receiving RT, 97% started treatment within 3 months; older age, black race, advanced stage, more comorbidities, and being unmarried were associated with longer time intervals between surgery and RT. There was no benefit to earlier initiation of RT; however, delays >3 months were associated with higher overall mortality (hazard ratio, 1.92; 95% confidence interval, 1.64-2.24) and cancer-specific mortality (hazard ratio, 3.84; 95% confidence interval 3.01-4.91). Conclusions: Reassuringly, early initiation of RT was not associated with survival. Although delays of >3 months are uncommon, they are associated with poor survival. Whether this association is causal or due to confounding factors, such as poor health behaviors, is unknown; until it is better understood, efforts should be made to initiate RT in a timely fashion