Although traditional prognostic factors were well balanced (such as age, menopausal status and tumour size), other confounding factors such as progesterone receptor status were not balanced (Saarto et al, 2001) and the oestrogen receptor status is unknown in the patient population of three trials (Elomaa et al, 1988; Kanis et al, 1996; Mardiak et al, 2000). The gene discussed is PGR; the disease is neoplasm.