Clinical and economic outcomes by first-line treatment among women with HR+/HER2– metastatic breast cancer in a large US health plan database

Abstract

Background: Guidelines recommend that women with hormone receptor–positive/human epidermal growth factor receptor 2–negative (HR+/HER2–) metastatic breast cancer (mBC) initiate hormonal therapy before chemotherapy. This study compared outcomes of women with mBC who received chemotherapy first vs hormonal therapy.

Methods: A retrospective cohort study of women with mBC was conducted using a large US commercial health plan database between January 1, 2008–April 30, 2013. Subjects had evidence of a HR+/HER2– tumor sub-type in a cancer registry and use of chemotherapy or hormonal therapy in claims. Subjects were continuously enrolled for ≥6 months after metastasis and assigned to cohorts for receiving chemotherapy only or hormonal therapy only during first-line (CT-1L vs HT-1L). Adjusted incidence rates of clinically significant events were compared using a negative binomial model, and adjusted healthcare costs were compared using a generalized linear model.

Results: Three hundred and twenty-four women with HR+/HER2– mBC met the selection criteria; 179 (55%) received CT-1L and 145 (45%) received HT-1L. Mortality rates did not differ between cohorts (unadjusted incidence rate ratio (IRR) = 1.67, 95% CI = 0.82–3.46; adjusted IRR = 0.64, 95% CI = 0.32–1.27). Adjusted average total all-cause healthcare costs were $11 090 for women with CT-1L and $6743 for women with HT-1L (cost ratio =1.64, 95% CI =1.36–1.99).

Conclusions: Observed use of first-line chemotherapy (>50%) was higher than expected given the HR + molecular profile of the tumors. Chemotherapy use during first-line did not appear to be associated with a survival benefit, but was associated with significantly higher costs compared with the use of hormonal therapy during first-line; however, this comparison is limited by demographic and baseline characteristic differences between the two cohorts. This study contributes to understanding real-world treatment patterns and the associated clinical and economic outcomes of using chemotherapy vs hormonal therapy as a first-line treatment option for the HR+/HER2– mBC population.

Keywords:

• Metastatic breast cancer
• HR+/HER2– sub-types
• Clinical and economic outcomes
• Chemotherapy
• Real-world data

Transparency

Declaration of funding

The study was sponsored by Pfizer Inc.

Declaration of financial/other relationships

Drs Smith, Zanotti, Bell, Perkins, and Horblyuk are employees of Pfizer Inc and own stock in the company. Drs Burton and DaCosta Byfield are employees of Optum, which received funds from Pfizer Inc for consulting and execution of the research reported in this manuscript; however, their employment at Optum is not dependent on research funds from Pfizer Inc. Dr Teitelbaum has no commercial interests to disclose. CMRO Peer Reviewer 1 has no relevant financial relationships to disclose. CMRO Peer Reviewer 2 has disclosed that he has received grants from Roche (past) and Novartis.

Acknowledgments

The authors thank Ying Fan, Yiyu Fang, and Feng Cao of Optum for their contributions to this study. Editorial support was provided by Anny Wu, PharmD, of Complete Healthcare Communications, LLC, and funded by Pfizer Inc. Results from this study have been published previously in a poster at the San Antonio Breast Cancer Symposium, December 9–13, 2014: San Antonio, TX.