Relation between estrogen receptor concentration and clinical and histological factors: their relative prognostic importance after radical mastectomy for primary breast cancer.

After modified radical mastectomy, 490 primary breast cancer patients were followed for a median of 75 months. Bloom grade was measured in 340 patients and ER status in 341. Follow-up of these patients has yielded the following results: (a) The value of traditional indices has been reaffirmed. (Cox's multivariate analysis identified, in order of decreasing importance, the number of invaded lymph nodes, the initial tumor size and the histological grade. Other variables were found to be of lesser importance and were correlated with the three main indices.) (b) The value of ER status disappeared after more than 3 years of follow-up. (c) ER positive patients fared better after recurrence. This was interpreted as being a consequence of their responsiveness to hormonal treatment.