PRL and breast carcinoma in situ: Similarly, the estimated association of prolactin with in situ breast cancer risk appeared stronger among nulliparous women compared to parous women, more pronounced in analysis restricted to postmenopausal women (ORlog2 = 5.10 (95% CI 1.23, 21.15), Ptrend = 0.02 in nulliparous women versus ORlog2 = 1.22 (95% CI 0.88, 1.68), Ptrend = 0.24 in parous women; Phet = 0.02).