“…This is consistent with the recent finding that the apparent protective effect of dietary vitamin A against cancer of the lung is practically limited to the squamous cell type (Kvale et al, 1983). As the great majority of cervical cancers are squamous cell in origin (Raphael & Waterman, 1951) and are thought to be preceded by squamous metaplasia (Johnson, 1969), the cervix would seem to be a promising site in which to investigate the role of vitamin A. Studies in Italy (La Vecchia et al, 1984), Japan (Hirayama, 1979), and the USA (Marshall et al, 1983;Romney et al, 1981) (Orr et al, 1985), while the other two studies showed no differences that were statistically significant (Bernstein & Harris, 1984;Lambert et al, 1985).…”