Abstract P3-07-23: Patient characteristics, clinical and economic outcomes of women with first-line therapy for HR+/HER2- metastatic breast cancer in a large US managed care health plan: Chemotherapy first vs. no chemotherapy first

Abstract

Abstract BACKGROUND: NCCN guidelines clearly identify when chemotherapy may be an appropriate therapeutic approach for metastatic breast cancer (mBC). This study compared patient characteristics, mortality rates, and health care costs by initial chemotherapy (CT) use among women with HR+/HER2- mBC. METHODS: A retrospective cohort study design was used to analyze administrative claims data linked to clinical information for commercial health plan enrollees with evidence of mBC between 1/2008 and 4/2013. Clinical status at diagnosis was obtained from physician reports, including date of diagnosis, hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status. Women with known HR+/HER2- subtype and diagnosed initially with Stage IV or Stages I-III with evidence of progression later to metastatic disease were evaluated for at least 6 months after their Stage IV diagnosis or first metastatic claim, or until death if sooner. Clinical characteristics were compared descriptively between women who initiated therapy with/without chemotherapy (CT 1st vs. no CT 1st, respectively) using t-test for continuous and chi-square test for categorical variables. Mortality was compared using the incidence rate ratio (IRR) and 95% confidence interval (CI) from a negative binomial distribution. Total average per-member-per-month (PMPM) health care costs were compared using a generalized linear model. Both the mortality rates and costs were adjusted for age, geographic region, stage at diagnosis, initial metastatic site(s), and initial use of CT. RESULTS: Of 349 women with HR+/HER2- mBC, 204 (58%) had CT 1st and 145 (42%) had no CT 1st. Median follow-up was 17 months, and median length of the first-line of therapy (1st LOT) was 4 months (including censored LOTs). The mean age of women with CT 1st was slightly lower than those without CT 1st (52 vs. 55 years, p<0.01), although the proportion ≥ 50 years old did not differ between cohorts (35% vs. 28%, p=0.14). Cohorts did not differ by geographic region or initial metastatic site(s) to brain, liver, or lung. Compared to women without CT 1st, a lower proportion of women with CT 1st were diagnosed de novo Stage IV (34% vs. 48%, p=0.01). Among women with CT 1st, 24 (12%) also received hormonal therapy (HT) during their 1st LOT. All women with no CT 1st (100%) initiated treatment with HT, of which the most common were 52 (36%) with tamoxifen, 41 (28%) with anastrozole, and 39 (27%) with letrozole. After adjustment for baseline characteristics, no cohort differences were found in mortality (IRR: 0.93, 95% CI: 0.50-1.72), however adjusted total average PMPM costs were significantly higher in women with CT 1st than those without ($11,666 vs. $6,639, p<0.001). CONCLUSION: In this study of commercially insured women with HR+/HER2- mBC, use of CT 1st (>50%) was higher than expected. While there were minor cohort differences in patient characteristics, CT 1st does not appear to be associated with a survival benefit, but was associated with significantly higher costs when compared to no CT 1st. Additional research is needed to determine subset(s) of mBC women with CT 1st likely to benefit from initial HT. Citation Format: Tanya Burton, Stacey DaCosta Byfield, Ying Fan, Yiyu Fang, Feng Cao, Gregory L Smith, Giovanni Zanotti, Timothy J Bell, Julia J Perkins, Ruslan Horblyuk, April Teitlebaum. Patient characteristics, clinical and economic outcomes of women with first-line therapy for HR+/HER2- metastatic breast cancer in a large US managed care health plan: Chemotherapy first vs. no chemotherapy first [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-07-23.