Adjuvant trastuzumab for 1 year after chemotherapy significantly improved long-term disease-free survival compared with observation in women with HER2-positive early breast cancer, a study published in The Lancet has shown.1

Previous research has demonstrated that trastuzumab significantly improves overall survival and disease-free survival in patients with HER2-positive early breast cancer; however, additional follow-up data are needed to determine the long-term impact of trastuzumab treatment on clinical outcomes.

The international, open-label, phase 3 HERA trial (ClinicalTrials.gov Identifier: NCT00045032) enrolled 5099 women with HER2-positive early breast cancer and randomly assigned them 1:1:1 to receive trastuzumab for 1 year, trastuzumab for 2 years, or observation after completion of primary therapy with surgery, chemotherapy, and/or radiation therapy.

After a median follow-up of 11 years, results showed that adjuvant treatment with trastuzumab for 1 year significantly reduced the risk of recurrence by 24% (hazard ratio [HR], 0.76; 95% CI, 0.68-0.86) and death by 26% (HR, 0.74; 95% CI, 0.64-0.86) compared with observation.

There was no significant difference in disease-free survival between patients treated with 2 years of trastuzumab and those treated for 1 year (HR, 1.02; 95% CI, 0.89-1.17).

Investigators estimated that 69% of patients treated with trastuzumab for 1 year, 69% of those treated for 2 years, and 63% of those who received observation were disease-free at 10 years. More than half (52%) of patients initially assigned to observation crossed over to receive trastuzumab.

Fewer than 5% of patients in the 1-year trastuzumab group experienced cardiac toxicity compared with approximately 7% of patients in the 2-year trastuzumab group and approximately 1% of those in the observation arm.

The findings suggest that 1 year of trastuzumab after primary therapy improves long-term disease-free survival and overall survival, with no additional benefit from 2 years of trastuzumab, in this population.

Reference

1. Cameron D, Piccart-Gebhart MJ, Gelber RD, et al. 11 years’ follow-up of trastuzumab after adjuvant chemotherapy in HER2-positive early breast cancer: final analysis of the HERceptin Adjuvant (HERA) trial. Lancet. 2017 Feb 16. doi: 10.1016/S0140-6736(16)32616-2 [Epub ahead of print]