Following on from the IMPACT trial, the ICR-CTSU in collaboration with the Royal Marsden Hospital, designed the POETIC (Perioperative Endocrine Therapy - Individualising Care, ISRCTN: 63882543) trial [20], a randomised controlled trial investigating aromatase inhibitor therapy in oestrogen positive early breast cancer prior to and after surgery (the perioperative treatment setting). Here, CYP19A1 is linked to breast cancer.