ImportanceAlthough longer times from breast cancer diagnosis to primary surgery have been associated with worse survival outcomes, the specific time point after which it is disadvantageous to have surgery is unknown. Identifying an acceptable time to surgery would help inform patients, clinicians, and the health care system.ObjectiveTo examine the association between time from breast cancer diagnosis to surgery (in weeks) and overall survival and to describe factors associated with surgical delay. The hypothesis that there is an association between time to surgery and overall survival was tested.Design, Setting, and ParticipantsThis was a case series study that used National Cancer Database (NCDB) data from female individuals diagnosed with breast cancer from 2010 to 2014 (with 5-year follow-up to 2019). The NCDB uses hospital registry data from greater than 1500 Commission on Cancer–accredited facilities, accounting for 70% of all cancers diagnosed in the US. Included participants were females 18 years or older with stage I to III ductal or lobular breast cancer who underwent surgery as the first course of treatment. Patients with prior breast cancer, missing receptor information, neoadjuvant or experimental therapy, or who were diagnosed with breast cancer on the date of their primary surgery were excluded. Multivariable Cox regression was used to evaluate factors associated with overall survival. Patients were censored at death or last follow-up. Covariates included age and tumor characteristics. Multinomial regression was performed to identify factors associated with longer time to surgery, using surgery 30 days or less from diagnosis as the reference group. Data were analyzed from March 15 to July 7, 2022.ExposuresTime to receipt of primary breast surgery.MeasuresThe primary outcome measure was overall survival.ResultsThe final cohort included 373 334 patients (median [IQR] age, 61 [51-70] years). On multivariable Cox regression analysis, time to surgery 9 weeks (57-63 days) or later after diagnosis was associated with worse overall survival (hazard ratio, 1.15; 95% CI, 1.08-1.23; P < .001) compared with surgery between 0 to 4 weeks (1-28 days). By multinomial regression, factors associated with longer times to surgery (using surgery 1-30 days from diagnosis as a reference) included the following: (1) younger age, eg, the adjusted odds ratio (OR) for patients 45 years or younger undergoing surgery 31 to 60 days from diagnosis was 1.32 (95% CI, 1.28-1.38); 61 to 74 days, 1.64 (95% CI, 1.52-1.78); and greater than 74 days, 1.58 (95% CI, 1.46-1.71); (2) uninsured or Medicaid status, eg, the adjusted OR for patients with Medicaid undergoing surgery 31 to 60 days from diagnosis was 1.35 (95% CI, 1.30-1.39); 61 to 74 days, 2.13 (95% CI, 2.01-2.26); and greater than 74 days, 3.42 (95% CI, 3.25-3.61); and (3) lower neighborhood household income, eg, the adjusted OR for patients with household income less than $38,000 undergoing surgery 31 to 60 days from diagnosis was 1.35 (95% CI, 1.02-1.07); 61 to 74 days, 1.21 (95% CI, 1.15-1.27); and greater than 74 days, 1.53 (95% CI, 1.46-1.61).Conclusions and RelevanceFindings of this case series study suggest the use of 8 weeks or less as a quality metric for time to surgery. Time to surgery of greater than 8 weeks may partly be associated with disadvantageous social determinants of health.