The use of hormone replacement therapy in patients after breast cancer.

Four prospective randomized studies and at least 15 observational studies investigating hormone replacement therapy (HRT) after breast cancer are available. Only the Hormonal replacement therapy After Breast cancer: Is iT Safe (HABITS) study shows an increased risk of relapse. This is probably associated with the relatively high number of patients with HRT treatment after estrogen receptor-positive cancers as well as to the preferred use of estrogen/progestin combined preparations.