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Utilization and Outcomes of Breast Brachytherapy in Younger Women
Grace L Smith1, Jinhai Huo2, Sharon H Giordano3
1Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas; Department of Health Services Research, The University of Texas MD Anderson Cancer Center, Houston, Texas.
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.
