To explain the improved OS of the carriers of the wild-type G allele, Nowell et al. [8] suggested in their study of TAM treated breast cancer patients (n = 160) that the sulfated form of 4-OH-TAM is reabsorbed in the kidney and further desulfated in the breast tumours by steroid sulfatase, thus prolonging the duration of action of the active 4-OH-TAM. This evidence concerns the gene STS and breast cancer.