Abstract 226P
Background
The impact of Body Mass Index (BMI) on receptor positive (HR+) breast cancer (BC) risk of recurrence has been deeply investigated but there are still few data concerning the BMI role in HER2 positive (HER2+) BC patients (pts). The aim of our study is to evaluate the impact of BMI on HER2+ BC pts treated with adjuvant trastuzumab in terms of disease-free survival and cardiac toxicity.
Methods
From 1992 to 2016, 694 consecutive HER2+ BC pts were enrolled in a monocentric observational study. Among these pts we selected 201 pts treated with adjuvant trastuzumab after surgery of the primary tumor and with available BMI data. Exclusion criteria were neoadjuvant chemotherapy (117 pts), metastatic disease ab initio (26 pts), treatment with adjuvant Pertuzumab or Lapatinib (30 pts), not receiving adjuvant trastuzumab (92 pts), missing adjuvant therapy data (27 pts) and missing BMI data (201 pts). 5-year disease free survival (5yDFS) rates analyses were performed using Kaplan Meyer method to evaluate differences between the following groups: BMI<25 vs.BMI≥25, HR+ BMI<25 vs.HR+ BMI≥25, receptor negative (HR-) BMI<25 vs.HR- BMI≥25. Moreover, in 151 pts with available cardiac data, we analyzed the number of cardiac events, defined as a left ventricular ejection fraction (LVEF) decline of ≥10% from baseline and/or LVEF<50%, in BMI<25 pts and in BMI≥25 pts, using χ(2) test.
Results
Median age was 56 years (28-85), 72 pts (36%) were premenopausal and 129 pts (64%) were post-menopausal. 123 pts (61%) had BMI<25 and 78 (39%) had BMI≥25. HR were negative in 79 pts (39%) and positive in 122 pts (61%). At a median follow up of 7.2 yrs, there was no difference in 5yDFS between BMI<25 pts and BMI≥25 pts (93% vs.94%, p=0.653). 5yDFS was 95% in HR+ BMI<25 vs.97% HR+ BMI≥25 (p=0.535), 91% in HR- BMI<25 vs.91% HR- BMI≥25 (p=0.730), consistent with overall population result. In 151 pts with available cardiac toxicity data we identified 15 cardiac events (15%) in BMI<25 group and 10 cardiac events in BMI≥25 group (19%) (p=0.522).
Conclusions
Our retrospective analysis did not show a significant impact of BMI on 5yDFS or cardiotoxicity in early HER2+ BC pts treated with adjuvant trastuzumab.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
C. Molinelli: Travel/Accommodation/Expenses: Novartis; Travel/Accommodation/Expenses: Istituto Gentili; Travel/Accommodation/Expenses: Ely Lilly. L. Del Mastro: Advisory/Consultancy: Roche; Advisory/Consultancy: Novartis; Advisory/Consultancy: Eisai; Advisory/Consultancy: Pfizer; Advisory/Consultancy: AstraZeneca; Advisory/Consultancy: Ipsen; Advisory/Consultancy: Eli Lilly; Advisory/Consultancy: MSD; Advisory/Consultancy: Seattle Genetics; Advisory/Consultancy: Genomic Health. F. Poggio: Travel/Accommodation/Expenses: Takeda; Honoraria (self), Travel/Accommodation/Expenses: Ely Lilly; Honoraria (self): Merck Sharp and Dohme; Honoraria (self): Novartis. C. Dellepiane: Travel/Accommodation/Expenses: Roche; Honoraria (self), Travel/Accommodation/Expenses: Novartis. M. Lambertini: Honoraria (self), Advisory/Consultancy: Roche; Honoraria (self): Theramex; Honoraria (self): Lilly. C. Bighin: Honoraria (self): Roche; Honoraria (self): Novartis; Honoraria (self): Lilly. All other authors have declared no conflicts of interest.