Factors Associated With a Delay in Postmastectomy Radiation Therapy.

BACKGROUND While the optimal time interval between mastectomy and postmastectomy radiation therapy (PMRT) has not been well-elucidated, a delay in PMRT has been associated with increased local recurrence. We sought to determine factors associated with a delay in PMRT beyond 12 weeks in patients not undergoing adjuvant chemotherapy. METHODS Medical records of breast cancer patients who underwent mastectomy at our institution between January 2010 and December 2017 who subsequently received PMRT were retrospectively reviewed. As adjuvant chemotherapy can delay PMRT, patients receiving adjuvant chemotherapy were excluded. Factors associated with a delay in PMRT (defined as > 12 weeks from the time of mastectomy) were analyzed. RESULTS Among the 89 patients who met our inclusion criteria, the mean time from mastectomy to PMRT was 11.4 weeks. 24 patients (27.0%) had PMRT > 12 weeks after mastectomy. Factors associated with a delay in PMRT included black race (P = 0.031), younger age (P = 0.047), higher body mass index (P = 0.015), contralateral prophylactic mastectomy (P = 0.033), longer initial hospital length of stay (P = 0.001), and more complications (P = 0.025). On multivariable analysis controlling for all of these factors, only initial hospital length of stay (OR 1.63; 95% CI: 1.07-2.49; P = 0.024) was associated with a delay in PMRT. CONCLUSION Over a quarter of patients not undergoing adjuvant chemotherapy have a delay in PMRT beyond 12 weeks from the time of mastectomy. Length of initial hospital stay is the key driver in delaying PMRT.