The question of the role of adjuvant chemotherapy for so-called stage I breast cancers is easy to answer: there is none. A large cooperative study on breast cancer produced data supporting the thesis that recurrence was delayed by adjuvant chemotherapy with thiotepa given in conjunction with radical mastectomy.46In some ways the study was defective, partially as a result of factors external to the design and conduct of the investigation. A second more comprehensive and better designed study has been under way since October 1961. This study has features which do not permit publication of critical information until completion of the study unless an adverse effect was noted. From a theoretical standpoint, patients with stage I lesions (determined by pathologic examination) are the ones most apt to benefit from receiving effective systemic therapy in conjunction with excision of the primary lesion. Proof of this thesis will be difficult. First,