Dépistage du cancer cervical.

Résultats d'une étude suédoise incluant 1.230 cas et 6.150 témoins

les femmes qui n'ont pas eu de frottis aux échéances recommandés

tous les 3 ans entre 23 et 50 ans et
tous les 5 ans entre 51 et 60 ans)

ont multiplié par 2,52 le risque de cancer cervical
et par 4,82 le risque que ce cancer soit avancé.

Andrae & Coll., Journal of the National Cancer Institute, avril 2008 ; 100 (9) : 622-629.

Background: The effectiveness of cervical cancer screening programs differs widely in different populations. The reasons for these differences are unclear. Routine and comprehensive audits have been proposed as an ethically required component of screening. We performed a nationwide audit of the effectiveness of the Swedish cervical cancer screening program.

Methods: We identified all invasive cervical cancer cases that were diagnosed in Sweden from January 1, 1999, through December 31, 2001, and had been reported to the Swedish Cancer Registry (n = 1230 cases). We verified the diagnoses by histopathologic rereview and matched each case subject to five (population-based) age-matched control subjects who were identified from the National Population Register. The Pap smear screening histories for case and control subjects were reviewed for a 6-year period using the National Cervical Cancer Screening Register, which contains data on essentially all relevant cytological and histological diagnoses in Sweden. Odds ratios (ORs), and their 95% confidence intervals (CIs), of cervical cancer according to screening history were calculated in conditional logistic regression models. All statistical tests were two-sided.

Results: Women who had not had a Pap smear within the recommended screening interval had higher risk of cervical cancer than women who had been screened (OR = 2.52, 95% CI = 2.19 to 2.91). This risk was similarly increased for all age groups (Phomogeneity = .96). The risk for nonsquamous cell cervical cancers (OR = 1.59, 95% CI = 1.20 to 2.11) was also increased. Women who had not had a Pap smear within the recommended screening interval had a particularly high risk of advanced cancers (OR = 4.82, 95% CI = 3.61 to 6.44). Among women who had been screened within the recommended interval, those with abnormal Pap smears had a higher risk of cervical cancer than those with normal smears (OR = 7.55, 95% CI = 5.88 to 9.69) and constituted 11.5% of all women with cervical cancer.

Conclusions: Nonadherence to screening intervals was the major reason for cervical cancer morbidity. The screening program was equally effective for women of all ages and was also effective against nonsquamous cancers-