DISEASE CHARACTERISTICS: Histologically proven adenocarcinoma of the breast with at least 4 involved axillary and/or intramammary lymph nodes No known T4, N3, or M1 disease Dermal lymphatic involvement without clinical inflammatory changes (edema, peau d'orange, erythema) allowed Must have undergone breast conserving surgery or modified radical mastectomy plus axillary lymph node dissection Surgical margins negative for invasive or noninvasive ductal carcinoma At least 10 nodes sampled No more than 12 weeks since definitive surgery Synchronous bilateral breast carcinoma allowed if: Diagnosed within 4 weeks of initial histologic diagnosis One breast meets the eligibility criteria Other breast has fewer than 10 involved nodes and is not N3 or T4 Both breasts treated by modified radical mastectomy or breast conserving surgery with axillary node dissection Concurrent registration on S9719 Hormone receptor status: Not specified