Pills, partners and preventive prospects: in-situ cancer of the cervix
McMichael, A.J.; Hiller, J.E.
Medical Journal of Australia 150(3): 114-116
1989
ISSN/ISBN: 0025-729X PMID: 2541323 Document Number: 357989
Australian women face a lifetime risk of dying of cervical cancer of 1 in 250. Current epidemiological evidence suggests that the age at 1st sexual intercourse and the number of sexual partners are important risk factors for cervical carcinogenesis. Other risk factors for invasive cervical cancer include cigarette smoking, deficiencies of dietary and plasma micronutrients, and oral contraceptive (OC) use. The recently documented increased risk of invasive cervical cancer associated with longterm OC use may in part reflect uncontrolled confounding by other factors, especially the likely association of OCs with greater exposure of the cervix to infectious agents such as human papillomavirus. Moreover, any association of present cancer with past use of OCs may not reflect the risk that is associated with the currently prescribed lower-dose agents. The profiles of risk appear to be similar for invasive carcinoma of the cervix and carcinoma in situ, confirming the view that carcinoma in situ is the main precursor lesion for invasive cancer of the cervix. A recent case-control study conducted in Sydney found a 50% increase in the risk of carcinoma in situ in ever users of OCs compared to never users, and the risk increased with increasing duration of OC use. The mode of the possible action of OCs on the risk of cervical cancer remains unclear. Recent studies have demonstrated that certain sex steroids directly activate viral DNA that is incorporated into the DNA of epithelial cells and that in vitro interaction occurs between such hormones and human papillomavirus type 16 DNA in the enhanced induction of carcinogenesis in cultured cells. This evidence that a sexually transmitted infectious agent contributes to the etiology of cervical cancer offers a clear direction for preventive action.