The effect of exogenous hormones, smoking and HPV on the incidence of screen detected pre-invasive cervical cancer.

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Cervical cancer is one of the leading causes of cancer death in women internationally. About 15,000 women are detected in NSW annually as having pre-invasive cervical cancer (cervical intraepithelial neoplasia (CIN) grade I, II or III). Infection with certain high risk human papillomaviruses is known to be necessary for the development of cervical cancer. In addition, recent long term exposure to smoking and to hormonal contraception are two new factors considered as independent risk factors for the disease. Hormone replacement therapy (HRT) preparations taken around the menopause are a similar composition to hormonal contraceptives, (oestrogen and progestogen), therefore women on HRT may also be at increased risk. No comprehensive study exists internationally to measure the relative importance of these exogenous hormones on the development of pre-invasive cervical cancer in a way that is of public health relevance (e.g. recent long-term use of oral contraceptives and time since stopped, and among smokers and non-smokers). No Australian data are available on the proportion of women who are current users of hormonal contraceptives or HRT. No local prevalence data on the major high risk HPV subtypes (e.g. 16, 18, 33, 45) are available for Australia to describe its distribution and to inform the cervical screening program and future vaccine initiatives. The NSW Pap Test Register holds the screening history of all women on the cervical screening program, hence this is an ideal source for recruiting a representative sample into a study. We wish to conduct a large study of ~2600 NSW women using the NSW Pap Test Register to measure the relative importance of hormones, smoking and HPV infection on the development of CIN II or III.