1, chemotherapy (mainly refers to the day of chemotherapy) and radiation therapy during try to stop using all vitamins (pills), especially vitamin C can not eat, please remember. Domestic patients usually like to take a multivitamin every day, but the latest study found that it will affect the efficacy of chemotherapy and radiotherapy, so please stop using it immediately, especially the day of chemotherapy. 2, when taking oral endocrine therapy, especially patients of Letrozole, Renindezvous, Anoxin, it is best to take vitamin D and calcium tablets twice a day, 1 tablet each time, and do not take any other vitamins. Patients taking oral phlebotomy and triamcinolone need only vitamin D supplementation.