The epidemiology of cervical neoplasia.

Controversial topics in the epidemiology of cervical neoplasia are reviewed, in the light of data from studies conducted in Italy and indications from the literature. The downward trends registered over the last three decades in mortality from cervical cancer seem to be levelling off in the younger age groups (below age 45). This may be partly due to changes in sexual habits in younger women, but is certainly attributable to deficiencies in cervical screening. Pap smear, in fact, strongly reduces the risk of cervical neoplasia, the protection (as suggested by data from a case control study), being long lasting (over five years and perhaps around 10-15 years) for invasive cancers. The results of the same case-control study indicate that, although women with pre-invasive and invasive conditions seem to share several unspecific indicators of sexual habits (i.e., total number of partners and age at first intercourse), they appear to differ with regard to clinical history of specific venereal disease. In fact, genital warts, herpes genitalis and trichomoniasis were more frequent in cases of intraepithelial neoplasia, but not of invasive cancer. The implications of these findings, and of other controversial points in the epidemiology of cervical neoplasia, such as oral contraceptives, cigarette smoking and diet, are discussed with regard to indications from other disciplines (chiefly molecular hybridization and stochastic models of carcinogenesis).