49P - Survival outcomes of HER2-positive breast cancer patients treated with neoadjuvant therapy at a single cancer centre in India

Background

There is scant data on outcomes of HER2-positive breast cancer patients treated with neoadjuvant therapy in real-world, resource-constrained settings. Factors affecting outcomes in patients who achieve pathological complete response (pCR) are insufficiently explored.

Methods

This was a retrospective analysis of HER2-positive breast cancer patients treated with neoadjuvant chemotherapy (NACT) with or without HER2-targeted therapy between Jan 2014 & Dec 2018. The endpoints were pCR, event-free survival (EFS) and overall survival (OS).

Results

1004 patients were included in the analysis with a median age of 47 years, 533 (53.1%) with cT3/T4, 466 (46.4%) with cN2/3, 527 (52.5%) with ER/PR-positive tumours, 528 (52.3%) received HER2-therapy with NACT, and 711 (70.8%) received it anytime during curative treatment. The 5-year EFS in all patients was 63.5% (95%CI 60.36-66.63%) and was significantly higher with pCR vs without pCR (86.1% vs 57.0%, HR 0.282, 95%CI 0.198-0.401, p=0.000), cT1/T2 vs cT3/T4 (66.8% vs 60.6%, HR 0.767, 95%CI 0.626-0.939, p=0.01), cN0/N1 vs cN2/N3 (67.9% vs 58.5%, HR 0.772, 95%CI 0.632-0.944, p=0.01), and ever-received vs never-received HER2-therapy (69.5% vs 50.1%, HR 0.537, 95%CI 0.438-0.659, p=0.000). The 5-year OS in all patients was 69.6% (95%CI 66.66-72.54%) and was significantly higher in pCR, cT1/T2, cN0/N1, and ever-received HER2-therapy subgroups. In the pCR subgroup (n=226), there was a trend towards higher 5-year EFS among patients with cT1/T2 vs cT3/T4 (90.0% vs 82.5%, HR 0.546, 95%CI 0.270-1.103, p=0.08), cN0/N1 vs cN2/N3 (89.3% vs 82.4%, HR 0.641, 95%CI 0.326-1.262, p=0.195), and ER/PR-positive) vs ER/PR-negative tumours (90.9% vs 83.0%, HR 0.609, 95%CI 0.291-1.274, p=0.183), but there was no difference between ever-received (n=204) vs never-received (n=22) HER2-therapy (86.1% vs 86.4%, HR 0.880, 95%CI 0.309-2.504, p=0.811).

Conclusions

The receipt of HER2-targeted therapy and achievement of pCR significantly impact survival of HER2-positive breast cancer patients treated with neoadjuvant therapy. In patients who achieve pCR baseline disease burden tends to influence survival but not receipt of HER2-targeted therapy.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.