Assessment of hormone receptor status in breast cancer.

The aim of the present paper was to investigate the most adequate method for the assessment of hormone receptor status in breast cancer in routine clinical settings. Subjects were 486 patients with primary breast cancer who underwent surgery and postoperative tamoxifen monotherapy in 1982-1993. Using representative sections of the primary lesion in each patient, estrogen receptors (ER) were immunohistochemically stained. Patients were divided into ER-positive and ER-negative groups using various methods, and then overall and 5 year recurrence-free survival rates were compared. The results of ER status, which are diagnosed on entire cancer area and invasive cancer area, matched in 98% of cases. When assessing prognosis based on the proportion of positive cells, a significant difference in 5 year recurrence-free survival was seen between ER-positive and ER-negative patients for a cut-off of 10%, and in overall and 5 year survival for a cut-off of 33%. Based on the proportion and the intensity of positive cells (Allred score), a significant difference was seen in overall and 5 year survival for a cut-off in total scores between 4 and 5 points. When assessing hormone receptors of breast cancer in routine clinical settings, it is sufficient to determine the proportion of positive cells in the entire cancer area.