Utilization and Outcomes of Breast Brachytherapy in Younger Women

作者：Smith Grace L; Huo Jinhai; Giordano Sharon H; Hunt Kelly K; Buchholz Thomas A; Smith Benjamin D^*

来源：International Journal of Radiation Oncology, Biology, Physics, 2015, 93(1): 91-101.

DOI：10.1016/j.ijrobp.2015.05.010

Purpose: To directly compare (1) radiation treatment utilization patterns; (2) risks of subsequent mastectomy; and (3) costs of radiation treatment in patients treated with brachytherapy versus whole-breast irradiation (WBI), in a national, contemporary cohort of women with incident breast cancer, aged 64 years and younger.
Methods and Materials: Using MarketScan health care claims data, we identified 45,884 invasive breast cancer patients (aged 18-64 years), treated from 2003 to 2010 with lumpectomy, followed by brachytherapy (n = 3134) or whole-breast irradiation (n = 42,750). We stratified patients into risk groups according to age (Age<50 vs Age >= 50) and endocrine therapy status (Endocrine- vs Endocrine+). "Endocrine+" patients filled an endocrine therapy prescription within 1 year after lumpectomy. Pathologic hormone receptor status was not available in this dataset. In brachytherapy versus WBI patients, utilization trends and 5-year subsequent mastectomy risks were compared. Stratified, adjusted subsequent mastectomy risks were calculated using proportional hazards regression.
Results: Brachytherapy utilization increased from 2003 to 2010: in patients Age<50, from 0.6% to 4.9%; patients Age >= 50 from 2.2% to 11.3%; Endocrine- patients, 1.3% to 9.4%; Endocrine+ patients, 1.9% to 9.7%. Age influenced treatment selection more than endocrine status: 17% of brachytherapy patients were Age<50 versus 32% of WBI patients (P<.001); whereas 41% of brachytherapy patients were Endocrine-versus 44% of WBI patients (P = .003). Highest absolute 5-year subsequent mastectomy risks occurred in Endocrine-/Age<50 patients (24.4% after brachytherapy vs 9.0% after WBI (hazard ratio [HR] 2.18, 95% confidence interval [CI] 1.37-3.47); intermediate risks in Endocrine-/Age >= 50 patients (8.6% vs 4.9%; HR 1.76, 95% CI 1.26-2.46); and lowest risks in Endocrine+ patients of any age: Endocrine+/Age<50 (5.5% vs 4.5%; HR 1.18, 95% CI 0.61-2.31); Endocrine+/Age >= 50 (4.2% vs 2.4%; HR 1.71, 95% CI 1.16-2.51).
Conclusion: In this younger cohort, endocrine status was a valuable discriminatory factor predicting subsequent mastectomy risk after brachytherapy versus WBI and therefore may be useful for selecting appropriate younger brachytherapy candidates.