To the Editor.
—The Special Communication on ERT in breast cancer survivors1 noted potential National Cancer Institute support of new clinical investigations. A National Cancer Institute Working Group considered certain hormone combinations for short-term menopausal symptom relief studies but did not support the contention by Cobleigh et al that ERT or ERT with tamoxifen can yet be safely tested in large phase III trials.2The article provided limited evidence on ERT safety for breast cancer survivors. First, data on recurrence and survival effects were presented but were limited to studies of "past" or "ever recorded" ERT use. These studies were confounded by the reversible nature of hormonal promotion; meaningful contingencies of current or long-term use were not presented.2 The recurrence/survival studies were also too small to address the central question of the relative risk (RR) of tumor reactivation or second primary tumor. Survival studies may also have