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Monday, 16 June 2003
Page: 16373


Dr WASHER (1:22 PM) —I thank the Member for Charlton for bringing to the House this important debate on cancer of the uterine cervix, as this is the eighth most common cancer in women. It is also noted that, as a result of the National Cervical Screening Program, the incidence of and mortality from cervical cancer have been falling for many years. In particular, I agree with the need to encourage all women in Australia to undertake regular screening using the pap test to detect the cytological changes indicating the possible presence of precursor lesions—lesions that could give rise to invasive disease if not removed. Thus, the main role of this screening test is to identify patients who require further evaluation and possible cervical biopsy.

Pap smear screening should begin when a female becomes sexually active or reaches 18 years of age and should continue annually for at least three years. If three or more pap smears are negative and the patient's risk of cervical cancer is average, further testing can be performed at the physician's discretion—perhaps every two to three years, although the optimal frequency in this situation has not been established. Continued annual pap smears for women at high risk of developing cervical cancer are recommended.

Cervical cancer is typically a disease of women in their fifth and sixth decades, whereas premalignant cervical lesions are often discovered in women younger than 40 years of age. This rather large gap in the age distribution between precursor lesions and invasive cancer is indicative of a long latency period for malignant transformation. Infection with human papilloma virus, HPV, most commonly subtypes 16, 18, 31, 33 and 35, is largely responsible for the development of precursor lesions and subsequent transformation to invasive disease. Not surprisingly, factors that predispose to transmission of this sexually transmitted virus are associated with an increased risk of the development of cervical cancer. A history of smoking and immunosuppression confers a high risk.

George Papanicolaou MD, from whom the pap smear derived its name, had a PhD in zoology. In 1943 Dr Papanicolaou, together with Herbert Traut, a gynaecologist, published `Diagnosis of uterine cancer by the vaginal smear'. This publication demonstrated how lesions could be detected in their preinvasive phase, creating a turning point in the management of cervical cancer, the most deadly form of cancer at the time.

No randomised controlled trials have been done in Australia demonstrating ThinPrep to be better than the normal pap smear. However, a US paper showed that ThinPrep decreased the amount of inconclusive pap smears in US women. In Perth, WA, PathCentre, a large pathology unit, have demonstrated that ThinPrep has a 0.8 per cent better pick-up with high-grade lesions. They also noted that the unsatisfactory pap smear rate was lower using ThinPrep compared to using the normal pap smear—that is, it was 0.3 per cent compared to 1.5 per cent. ThinPrep was better with bloodstained and inflamed smears.

Scotland has moved to ThinPrep solely. Finland uses only normal pap tests but has total population compliance and has the lowest rate of cancer of the cervix at two per 100,000 of population. Western Australia's rate is seven per 100,000. The Indigenous Australian rate is 14 per 100,000. ThinPrep requires demanding education for a screener and is much better performed by a computer, but huge costs are involved in computer screening. Finland's experience shows complete compliance using normal pap tests is superior to ThinPrep used only in a selected population. In Australia money should definitely be put into achieving complete compliance using the normal pap test, as in Finland. ThinPrep should be used in bloodstained and inflamed smears.

The most common cancer of the cervix is squamous cell carcinoma, which generally originates at the transitional zone on the cervix. The second most common cancer is adenocarcinoma, originating in the endocervical canal. Skilled sampling of these regions when performing a pap test is critical. The big advantage of ThinPrep is that it is in solution—it uses liquid based cytology—which allows DNA testing to subtype human papilloma virus in patients with this infection and other venereal diseases such as chlamydia. (Time expired)