'Driving' Rates Down: A Population-Based Study of Opening New Radiation Therapy Centers on the Use of Mastectomy for Breast Cancer.

Background: Two new cancer centers providing radiation therapy opened in Alberta, Canada, in 2010 and 2013, respectively. We aimed to assess whether opening the new RT centers influenced mastectomy rates for breast cancer.

Method: Breast cancer patients who underwent surgery from 2004 through 2015 were identified from the Alberta Cancer Registry. Mastectomy rates for 64 predefined health status areas (HSAs) were calculated after adjusting for patient and system factors. Variations in mastectomy rates among the HSAs were quantified using weighted coefficient of variation (CV). Multivariable logistic regressions were performed to determine associations between driving time and mastectomy use in the entire cohort and in subgroups.

Results: Of the 21,872 patients, the proportion of patients who lived a ≤ 60 min drive from the nearest RT center significantly increased from 68.8% (95% CI 67.7-69.9%) to 80.7% (95% CI 79.5-81.9%) during the study period. Concurrently, the crude provincial mastectomy rate decreased from 56.2% (95% CI 55.3-57.1%) to 45.3% (95% CI 44.1-46.5%). However, variation in adjusted mastectomy rates (weighted CV) across the 64 HSAs increased from 9.5 to 14.6. Factors associated with mastectomy included age, larger tumor size, lymph node involvement, higher tumor grade, molecular subtype, lobular histology type, more comorbidities, academic institution, region, earlier period of diagnosis, and longer driving time to the nearest RT center.

Conclusions: Opening new RT centers in previously underserved regions reduced driving times to the nearest center, and was associated with a reduction in mastectomy rates; however, these reductions among regions across the province were not uniform.