Although NRTI was ineffective as a cancer prophylactic and had no direct antitumor activity in the MMTV-HER2/Neu model of breast cancer, it caused a dramatic effect on tumor relapse, significantly delaying tumor recurrence and prolonging progression-free survival, on average, from 25 d in the control group to 70 d in mice that received STV both prophylactically and during the time of 17-DMAG treatment, and to 95 d in mice that started drinking water with NRTI only from the time of commencement of the 17-DMAG treatment (Fig. 2D). This evidence concerns the gene ERBB2 and neoplasm.