Twelve months treatment is the current standard of care for adjuvant trastuzumab in patients with HER2 positive early breast cancer however the optimal duration is not known. Persephone is a non-inferiority randomised controlled trial comparing 6- to 12-months of trastuzumab. | Adjuvant trastuzumab duration trials in HER2 positive breast cancer what results would be practice-changing Persephone investigator questionnaire prior to primary endpoint results