Abstract P5-20-12: Adjuvant DCH vs TCH for low-risk (node negative); and FECDH vs TCH for high-risk (node positive) HER2+ breast cancer – A retrospective provincial analysis
Authors: Veitch ZW , Khan OF , Tilley D , Kostaras X , Tang PA , King K , Lupichuk S 
Published: February 2018

Background: Chemotherapy plus trastuzumab for early HER2+ breast cancer (BC) is associated with improved survival. Optimal regimens for low-risk (node negative) and high-risk (node positive) HER2+ breast cancers are unknown and choice of regimen varies in real-world clinical practice.

Objective: (1) For low-risk breast cancer, to compare DCH (4 cycles) and TCH (6 cycles) in terms of disease free (DFS) and overall survival (OS). (2) For high-risk breast cancer, to compare FECDH (6 cycles) and TCH (6 cycles) in terms of DFS and OS.

Methods: All women diagnosed from 2007-2014 with stage I-III, hormone receptor (HR) +/-, HER2+ BC receiving adjuvant chemotherapy plus trastuzumab (n=986) in Alberta, Canada were included. Patients with low-risk (node negative) disease were stratified into DCH (n=104) or TCH (n=360) cohorts for DFS/OS comparison (Kaplan-Meier). Patients with high-risk (node positive) disease were stratified into FECDH (n=145) or TCH (n=314) cohorts. Subgroup analysis of the high-risk cohorts by HR+/HER2+ and HR-/HER2+ for FECDH vs TCH were performed. Chi-square was used to evaluate for difference between cohort variables.

Low- Risk Cohort DCH TCH  n (104)%n (360)%Age (mean)55.3 53.0 Hormone Status    ER+ or PR+8682.727676.7ER and PR-1817.38423.3Grade    121.951.423230.88523.637067.327075.0Surgery    lumpectomy525010830.5mastectomy525024669.5

High-Risk Cohort FECDH TCH  n (145)%n (314)%Age (mean)50.2 53.6 Hormone Status    ER+ or PR+11579.323875.8ER and PR-3020.77624.2Grade    10051.6229206119.631168014678.8Surgery    lumpectomy3927.19831.2mastectomy10572.921668.8Node Status    N18357.219461.8N24128.37323.2N32114.54715

Results: Median follow-up was 58.1 months in the low-risk cohort and 63.1 months in the high-risk cohort. In the low-risk group, patients receiving TCH had more mastectomy (69.5%) than lumpectomy (30.5%; p&lt;0.001) compared to those receiving DCH (50%; 50%). No significant difference was seen in DFS (p=0.153) or OS (p=0.409) for patients in the DCH (92.3%; 95.2%) vs TCH (95.2%; 96.9%) cohorts. In the high-risk group, no significant difference was seen in DFS (p=0.226) or OS (p=0.164) for FECDH (92.4; 95.2%) or TCH (88.5%; 91.4%) respectively. In subgroup analysis of high-risk HR+/HER2+ BC, patients receiving FECDH demonstrated superior OS (98.3%; p=0.014) and a trend towards superior DFS (94.8%; p=0.069) relative to TCH patients (OS = 91.6%; DFS= 88.7%). Conversely, analysis of high-risk HR-/HER2+ BC, patients demonstrated higher DFS and OS for TCH (88.2%; 90.8%) relative to FECDH (83.3%; 83.3%); although this was non-significant (p=0.516; p=0.298) and likely underpowered. Nodal status was balanced between all groups (p=0.602).

Conclusion: In low-risk HER2+ BC, 4 cycles of DCH chemotherapy has high survival with similar outcomes to 6 cycles of TCH. In high-risk HER2+ BC, FECDH has comparable outcomes to TCH consistent with BCIRG-006. This study suggests that women with HR+/HER2+ breast cancer have improved OS with anthracycline containing regimens, such as FECDH. Although non-significant, patients with HR-/HER2+ BC may have some improvement in DFS and OS with TCH, a carboplatin containing regimen.

Citation Format: Veitch ZW, Khan OF, Tilley D, Kostaras X, Tang PA, King K, Lupichuk S. Adjuvant DCH vs TCH for low-risk (node negative); and FECDH vs TCH for high-risk (node positive) HER2+ breast cancer – A retrospective provincial analysis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-20-12.