P1-12-11: Neoadjuvant Chemotherapy-Trastuzumab Versus Neoadjuvant Chemotherapy Followed by Post-Operative Trastuzumab: A Multicentre Study.

Background: The addition of neoadjuvant trastuzumab (NAT) to neoadjuvant chemotherapy (NCT) has been shown to increase the rate of breast preservation and pathological complete response (pCR) compared to neoadjuvant chemotherapy alone (NCT). Furthermore, pCR following NCT-NAT is higher and pCR in this setting has been associated with improved disease free survival (DFS) compared to NCT alone group. No study has yet investigated the effect of NCT-NAT versus NCT followed by surgery followed by adjuvant trastuzumab (AT) on disease free survival and overall survival. Methods: All cases of invasive breast cancer diagnosed at Imperial College Healthcare NHS Trust, Christie Hospital and University Hospitals Bristol NHS Foundation Trust between 2006–2010 were reviewed and all early HER2 positive breast cancers receiving neoadjuvant treatment were identified, and case notes reviewed. Histopathological details, neoadjuvant treatment and where trastuzumab was initiated were recorded. pCR rate was documented and an efficacy analysis performed, disease free survival (DFS) and overall survival (OS) for the whole cohort, and for cases treated with NCT-NAT versus NCT alone followed by surgery and AT. Results: Between 2006–2010 122 invasive HER2 positive invasive breast cancers were treated in the neoadjuvant setting at the 3 centres. Of these 58% (71) received NCT alone and 42% (51) were treated with NCT-NAT. The median follow up for whole group was 26 months (range 4.9−70.4), 30.5 months (range 10.5−70.4) for NCT group and 20.1 months (range 4.9-59) for NCT-NAT group. 19 (27%) relapse/death events in NCT group compared to 7 (14%) in NCT-NAT group have occurred. For the whole cohort DFS at 3 years was 74.6% (95% CI; 69.5−79.7%), for those receiving NCT-NAT versus NCT alone, DFS was 75.7% (95% CI 85.4-66) versus 74% (95% CI 80.1−67.9) respectively. The OS at 3 years for whole group was 81.4% (95% CI 76–79.7%), for those receiving NAT versus NCT alone it was 81.6% (95% CI 71.2-92%) versus 81.2% (95% CI 74.9−87.5). The overall pCR rate was 26% (31/121), majority of pCR were in NAT group (61%). pCR occurred in 37% and 15% of patients receiving NCT-NAT and NCT respectively. 3 year DFS for those attaining a pCR was 92.3% (95% CI 87–97.5%) versus without pCR 70.9% (95% CI 65.1−76.7%). The 3 year OS was 85.7% (95% CI 72.5−98.9) for patients with a pCR compared to 80.7% (95% CI 74.9−86.5%) for those without PCR. Full details of the histopathological features, neoadjuvant therapy toxicity will be presented. Additional cases are being added and an up dated efficacy analysis will be presented. Conclusion :Patients treated with NAT upfront have a lower number of events. Currently, no difference is seen in DFS and OS for NAT versus NCT. However, pCR is higher with NAT and those with a pCR have a longer DFS and OS. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-12-11.