Utilization and Outcomes of Breast Brachytherapy in Younger Women.
OBJECTIVE
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
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).


CONCLUSIONS
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.
Department 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.
Grace L
GL
Smith
Department of Health Services Research, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Jinhai
J
Huo
Department of Health Services Research, The University of Texas MD Anderson Cancer Center, Houston, Texas; Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Sharon H
SH
Giordano
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Kelly K
KK
Hunt
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Thomas A
TA
Buchholz
Department 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. Electronic address: bsmith3@mdanderson.org.
Benjamin D
BD
Smith
D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001918:Brachytherapy / Q000191:economics / Q000706:statistics & numerical data* / Q000639:trends; D001943:Breast Neoplasms / Q000737:chemistry / Q000532:radiotherapy* / Q000628:therapy; D003131:Combined Modality Therapy; D005260:Female; D017048:Health Care Costs; D006801:Humans; D008408:Mastectomy / Q000706:statistics & numerical data* / Q000639:trends; D015412:Mastectomy, Segmental; D008875:Middle Aged; D018579:Patient Selection; D050397:Radiotherapy, Intensity-Modulated / Q000191:economics; D018570:Risk Assessment / Q000379:methods; D013997:Time Factors; D000068878:Trastuzumab; D016896:Treatment Outcome; D014481:United States; D055815:Young Adult
D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D000068878:Trastuzumab