The standard prognostic factors currently used for primary breast cancer decision making in the United States (reviewed in Clark, 2001) are: involved axillary node status (Fisher et al, 1978), histologic subtype, tumour size (Carter et al, 1989), nuclear grade (Fisher et al, 1980), oestrogen and progesterone receptor (ER and PR) status (McGuire, 1980), and measures of cellular proliferation (Clark et al, 1989). The gene discussed is PGR; the disease is breast cancer.