Neoadjuvant chemotherapy plus anti-HER2 treatment is increasingly becoming the treatment of choice for all but the lowest risk HER2+ early and locally advanced breast cancer (BC). Patients achieving a pathological complete response (pCR) have substantially better outcomes compared with non-pCR. We evaluated the pCR rates following neoadjuvant systemic therapy in our HER2+ BC population and determined the influence of tumour and patient characteristics, and adverse events on pCR rates, disease free survival (DFS) and overall survival (OS).
We retrospectively identified patients with early and locally advanced HER2+ BC who received neoadjuvant treatment from January 2013 to December 2017 and underwent subsequent surgery. pCR was defined as ypT0/is N0. Demographics, patient and disease characteristics, pathological responses, toxicities, dose delays and reductions were recorded. Statistical analysis was undertaken using Chi-squared, Kaplan Meier and Log-rank tests.
300 patients were identified. Median age was 51 years (range 25-78) and 286 (95.3%) patients had performance status (PS) 0. 11 (4.0%) patients had clinical stage I, 189 (63.0%) stage II and 100 (33.0%) stage III disease. 204 (68.0%) had grade 3 disease and 282 (94.0%) ductal histology. 185 (61.7%) patients had ER+ disease and 115 (38.3%) ER- disease. 155 (52.0%) patients were treated with chemotherapy plus Trastuzumab. 143 (48.0%) patients had chemotherapy plus Trastuzumab and Pertuzumab. pCR rate in the overall population was 54.3% and significantly better in the ER- compared with the ER+ subgroup ( 68.7 vs 45.4 %; p < 0.001). Patients on dual anti-HER2 blockade achieved higher pCR rates compared with those on Trastuzumab (56.6 vs 52.2%) although the difference was not statistically significant (p = 0.448). pCR rates were not influenced by age, PS, dose reductions or dose delays but were significantly lower in case of chemotherapy early discontinuation. With a median follow-up of 23 months, median DFS and OS were not reached.
In our analysis, pCR rate was similar to published data in the literature and was higher in the ER-/HER2 positive subgroup.
The Breast Unit, The Royal Marsden Hospital.
Has not received any funding.
All authors have declared no conflicts of interest.