“…In addition, 5 case-control studies of cervical carcinoma in situ (Irwin et al, 1988;Brock et al, 1989;Ory et al, 1977;Boyce et al, 1977;Fasal et al, 1981), 2 of intra-epithelial neoplasia (Harris et al, 1980;Hellberg et al, 1985), and 2 that included both in situ and invasive disease (Cuzick et al, 1989;Slattery et al, 1989), as well as 3 of squamous dysplasia (Ory et al, 1977;Fasal et al, 1981;Clarket al, 1985), all yielded relative risk estimates greater than one (ranging from 1.2 to 5.7) in the longest category of oral contraceptive use considered (ranging from over 2.5 to over 10 years). Increased risks of in situ and invasive cervical carcinomas have also been observed in 4 (Andolsek et al, 1983;Beral et al, 1988;Vessey et al,, 1983;Peritz et al, 1977) and 3 (Andolsek et al, 1983;Beral et al, 1988;Vessey et al, 1983) cohort studies respectively.…”