1. Does screening by "Pap" smears help prevent cervical cancer? A case-control study;Clarke, E.A.; Anderson, T.W.;Lancet,1979
2. Use of case-control studies in evaluation of screening programmes;Berrino, F.; Gatta, G.; D'Alto, M.; Crosignani, P.; Riboli, E.,1984
3. "Pap" smears and the risk of cervical neoplasia: quantitative estimates from a case-control study;C, La Vecchia; S, Franceschi; A, De Carli; M, Fasoli; A, Gentile; G, Tognoni;Lancet,1984
4. The impact of vaginal cytology on cervical cancer risks in Cali, Colombia;Aristizabal, N.; Cuello, C.; Correa, P.; Collazos, T.; Haenszel, W.;Int J Cancer,1984
5. Reduction of breast cancer mortality through mass screening with modem mammography: first results of the Nijmegen project 1975-1981. Lancet 1984; i: Several studies in different countries have evaluated the protection against invasive cervical cancer offered through Pap smears according to the interval since the last test and the number of smears. Overall the results of these studies show a considerable change in the risk of developing cervical cancer with time elapsed since last negative smear.1921 However the results of a study conducted in Manitoba, Canada,22 recently published, show no trend of increasing risk with increasing interval since the last test. The risk of invasive cervical cancer according to the interval since the last test is very important in determining how often to rescreen with a previous negative screening test;Verbeek, A.L.M.; Hendriks, J.H.C.L.; Holland, R.; Mravunac, M.; Sturmans, F.; Day, N.E.