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Long-term high-risk human papillomavirus incidence and clearance in population based cervical screening, as retrieved from a second screening round in the POBASCAM study

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Based on high-risk human papillomavirus (hrHPV) infection being the major causative factor of cervical cancer, substantial evidence has been obtained that cervical screening might become more efficient if testing for hrHPV is added to cervical cytology. Most evidence obtained so far from population-based research is based on follow-up studies with either relatively small numbers of women, or relatively short follow-up periods. However, it is clear that additional hrHPV testing can only lead to more cost-effective screening strategies if the screening interval can be prolonged for double negative women, i.e., women with normal cytology and a negative hrHPV test result. From previous research and preliminary simulation studies we anticipate that the screening interval in The Netherlands might be prolonged from 5 to 8 or even 10 years for double negative women. In order to address the additive value of hrHPV testing in increasing the efficacy of cervical screening we started in 1999 a large randomised prospective trial, the so-called POBASCAM trial (supported by ZONMW, nr. 30-5220). In this trial 44,102 women attending cervical screening have been tested by both cytology and hrHPV GP5+/6+-PCR, with hrHPV test results being blinded for half of the women (i.e. control group). Follow-up and referral policy is based on either cytology alone (control group) or cytology plus hrHPV test results (intervention group). The detection rate of lesions >=CIN 2/3 (cq. CIN 3) in relation to the number of repeat smears and referrals will be compared between both study groups within the time frame up to and including the next screening round (after 5 years). However, in this trial hrHPV testing is not included for the next screening round, so that no estimates can be made of the long-term incidence and clearance of hrHPV infections and consequently of the long-term protective effect of additive hrHPV testing. These data are indispensable for cost-effectiveness calculations when considering increased screening intervals. From 2004 onwards, women participating in the POBASCAM trial will be recalled for the next cervical screening round. To obtain the essential data of long-term incidence and clearance of hrHPV in women participating in cervical screening we aim to collect during a 2-year period HPV samples of the second screening round (n=12,500) in universal collection medium in order to address the following main question: 1) How many incident CIN 2/3 (cq. CIN 3) cases are found after 5 years in hrHPV negative women with normal cytology and borderline or mild dyskaryosis (BMD) at baseline and is hrHPV acquisition after 5 years predictive of these incident CIN2/3 (cq. CIN 3) lesions? Further sub-questions that will be addressed are: 2) What is the 5-year incidence rate of hrHPV infection in women who had an hrHPV negative normal or BMD smear at baseline? 3) What is the 5-year hrHPV clearance rate in women who had an hrHPV positive normal or BMD smear at baseline? 4) What is after 5 years the viral load in women with incident hrHPV infections who had an hrHPV negative normal smear at baseline and is there a relationship between viral load and incident CIN2/3 (cq. CIN 3) lesions? The data will be used for cost-effectiveness calculations of the effect of additional hrHPV testing on cervical screening. Apart from being essential for the items listed above it is also of utmost importance to safeguard HPV samples of the next screening round to consider other HPV detection methods such as SPF10 and Hybrid Capture 2, in case these assays would have advantages over GP5+/6+ PCR, as is currently being studied in project ZONMW 22000147.

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Projectnummer:
62000013
Looptijd: 100%
Looptijd: 100 %
2005
2007
Onderdeel van programma:
Projectleider en penvoerder:
Prof. dr. C.J.L.M. Meijer
Verantwoordelijke organisatie:
Amsterdam UMC - locatie VUmc