Estrogen (ER) and progesterone (PgR) receptor status
ER and PgR status were determined either by immunohistochemistry (in 60% and 62% of the cases, respectively) or using the dextran-coated charcoal method, and was classified either as positive or negative.
negative = negative hormone
positive = borderline or positive hormone receptor status
not available = missing data or the receptor status could not be assessed