For patients with HER2-positive breast cancer, a shorter course of trastuzumab plus chemotherapy may not be superior to the standard 1-year trastuzumab treatment, but it does decrease the risk of severe cardiac toxicity. The final results of the phase 3 randomized Short-HER trial, published in Annals of Oncology, have shown.

Chemotherapy plus 1 year of trastuzumab is the commonly accepted standard adjuvant treatment for HER2-positive breast cancer. The Short-HER trial investigated whether a 9-week course of trastuzumab was comparable to the standard 1-year treatment. The study included 1254 patients with HER2-positive breast cancer who received sequential anthracycline-taxane combinations and were randomized to 1 year or 9 weeks of adjuvant trastuzumab.

The 5-year disease-free survival for patients who underwent 1 year of trastuzumab was 88% vs 85% for those who followed the 9-week course. The 5-year overall survival was 95.2% for the longer course, and 95.0% for the shorter one. However, the shorter course was associated with a significantly lower number of cardiac events compared with the longer one.

Using a statistical inference of probability, the study authors estimated an 80% chance that the 9-week treatment is noninferior to the 1-year treatment. Based on the remaining possibility that the shorter treatment may be inferior, the study authors concluded that a 1-year course of trastuzumab should remain standard. 

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“This study failed to show the noninferiority of the shorter trastuzumab administration,” wrote the authors. “However, a 9-week administration decreases the risk of severe cardiac toxicity and can be an option for patients with cardiac events during treatment and for those with a low risk of relapse.” 

Reference

Conte P, Frassoldati A, Bisagni G, et al. Nine weeks versus 1 year adjuvant trastuzumab in combination with chemotherapy: final results of the phase III randomized Short-HER study.Ann Oncol. 2018;29(12):2328-2333.