OBJECTIVES: I. Determine whether dietary fat reduction will effectively prolong disease-free and overall survival in women surgically treated for early stage breast cancer who are receiving adjuvant therapy with or without either tamoxifen, cyclophosphamide, methotrexate, fluorouracil (CMF), doxorubicin, cyclophosphamide (AC), fluorouracil, doxorubicin, cyclophosphamide (FAC, CAF), or AC followed by paclitaxel. II. Evaluate whether differences in the lipid profile are associated with dietary group assignment and dietary fat.