Role of steroid hormone receptors as prognostic factors in primary breast cancer.

A review and update of published studies on estrogen receptor (ER) and progesterone receptor (PgR) as prognostic factors in breast cancer support the following conclusions. In stage I breast cancer, the lack of ER seems to be the most important factor for predicting earlier recurrence and poorer survival. In stage II breast cancer, PgR content appears to be better than ER content in predicting disease-free survival and PgR content is as important as ER content in predicting overall survival. The benefits of adjuvant endocrine therapy are better predicted by the presence or absence of PgR than by the presence or absence of ER. Measurement of proliferative activity (S-phase DNA) by thymidine labeling or flow cytometry and of aneuploidy by flow cytometry also provides prognostic information. The strong correlations between tumor receptor content, percent S-phase cells, and aneuploidy suggest that these measurements in concert might identify a subset of stage I breast cancer patients at increased risk for recurrence, who would thus be potential candidates for adjuvant therapy.