Abstract P3-07-24: Clinical characteristics and treatment utilization by tumor subtype among metastatic breast cancer patients in a large US managed care health plan
Authors: Burton Tanya , DaCosta Byfield Stacey , Fan Ying , Fang Yiyu , Cao Feng , Smith Gregory L , Zanotti Giovanni , Bell Timothy J , Perkins Julia J , Horblyuk Ruslan , Teitlebaum April 
Published: May 2015

BACKGROUND: Breast cancer is the second most common cause of cancer death among US women. Molecular profiling of breast cancer tumors is important for assessing prognosis and optimizing treatment. This study compared clinical characteristics and treatment utilization by tumor subtype among women with metastatic breast cancer (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 subtypes 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. Lines of therapy (LOTs) were identified based on the timing of claims for NCCN-recommended chemotherapy (CT), hormonal therapy (HT), and biologics (BIO). Clinical characteristics and treatments were compared descriptively across the HR/HER2 subtypes using t-test for continuous and chi-square test for categorical variables.

RESULTS: Table 1 presents study results by tumor subtype. There were 657 women identified (72% HR+ and 28% HR-). Median age was 53 years, and median follow-up was 16 months. Overall, 93% initiated therapy; of which, 48% started a 2nd LOT, 4% died, 28% discontinued or had a ≥90-day gap in therapy, and 20% had their 1st LOT censored due to disenrollment or end of study (EOS) period. More than half received CT during the 1st LOT, regardless of tumor subtype. Less than half of HR+ women initiated HT, and among HER2+ patients, most initiated a BIO agent.

Total (N=657)HR+/HER2- (N=365)HR-/HER2- (N=118)HR+/HER2+ (N=111)HR-/HER2+ (N=63)n(%)n(%)n(%)n(%)n(%)Diagnosed at Stage IV*265(40)145(40)37(31)50(45)33(52)Initial site of metastasis- Bone283(43)167(46)49(42)46(41)21(33)- Brain*105(16)45(12)32(27)17(15)11(17)- Liver*171(26)76(21)40(34)35(32)20(32)- Lung*127(19)64(18)36(31)11(10)16(25)- Other (incl. distant lymph nodes)494(75)277(76)97(82)76(68)44(70)Initial NCCN-recommended therapy (1st LOT)614(93)349(96)98(83)109(98)58(92)- CT*422(69)204(58)92(94)78(72)48(83)- BIO*124(20)1(&lt;1)4(4)68(62)51(88)- HT*210(34)169(48)9(9)31(28)1(2)- Reason for 1st LOT end-- Initiated a 2nd LOT*293(48)159(46)45(46)71(65)18(31)-- Died26(4)10(3)8(8)5(5)3(5)-- Discontinuation/gap*174(28)105(30)36(37)15(14)18(31)-- Censored*121(20)75(21)9(9)18(17)19(33)*p&lt;0.05. Not all groups are mutually exclusive. Percentages may not total 100% due to rounding or overlap.

CONCLUSION: In this study of commercially insured mBC women, initial therapy choices were generally consistent with NCCN guidelines for three of the four subtypes, while the largest subtype of HR+/HER2- women had a higher than expected utilization of CT. Future analyses of study data will investigate appropriateness of these initial treatments and their impact on clinical and economic outcomes.

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. Clinical characteristics and treatment utilization by tumor subtype among metastatic breast cancer patients in a large US managed care health plan [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 P3-07-24.