Effect and safety of dual anti-human epidermal growth factor receptor 2 therapy compared to monotherapy in patients with human epidermal growth factor receptor 2-positive breast cancer: a systematic review.

Dual anti-human epidermal growth factor receptor 2 (HER2) therapies have been shown to improve outcomes of HER2-positive breast cancer patients. We undertook a systematic review to compare treatment outcomes for patients who received single or combined anti-HER2 therapies.