Implications of oestrogen receptor status in primary breast carcinoma to the role of adjuvant chemotherapy in node-negative cases.

Recurrence occurred earlier in a small group of patients with node-negative breast carcinoma with oestrogen receptor (ER)-negative tumours, than in those in whom the tumour contained ER. The difference, indicative of an intrinsic advantage of an ER-positive tumour, was not seen following adjuvant chemotherapy. This finding could be explained on the basis of changes in the immunological balance between host and tumour brought about by treatment.