Conventional Pap Smear and Liquid-Based Cytology as Screening Tools in Low-Resource Settings in Latin America
Objective To evaluate the performance of the conventional Pap test and liquid-based cytology (LBC) in an ongoing multicenter trial testing optional screening tools (cytology, screening colposcopy, visual inspection with acetic acid, visual inspection with Lugols Iodine, cervicography and Hybrid Capture II [HCII] (Digene Brazil, Sao Paulo, Brazil) conventional and self-sampling), for cervical cancer in Brazil and Argentina. Study Design A cobort of 12,107 women attendingfour clinics (Campinas, Sao Paulo, Porto Alegre, Buenos Aires) were randomized into the 8 diagnostic arms. Women testing positive witb any of the tests were referred for colposcopy, and cervical biopsies were used as the gold standard to assess performance cbaracteristics of the diagnostic tests. Conventional Pap smears were sampled by all clinics (n = 10, 240), and LBC (Autogte (R) PREP, [TriPath Imaging, Burlington, North Carolina, U.S.A.], n = 320, and DNA-Citoliq (R) [Digene Brazil], n=1,346) was performed by 1 of the clinics. Results Conventional Pap smears showed no squamous intraepithelial lesions (normal) in 8,946 (87.4%) and LRC in 1,373 (82.4%). Using high grade squamous intraepithelial lesions (HSIL) as the cutoff, Pap smears predicted high grade (cervical intraepithelial neoplasia [CIN] 3) with OR 63.0 (95% CI, 36.90-107.70), standard error (SE) 59%, SP 97.8%, positive predictive value (PPV) 68.1% and negative predictive value (NPV) 96.7%. The same figures for Autocyte (R) PREP were: OR 9.0 (95% CI, 2.43-33.24), sensitivity (SE) 33.3%, specificity (SP) 100%, PPV 100% and negative PV (NVP) 88.8%. DNA-Citoliq (R) detected CIN 3 as follows: OR 11.8 (95% CI 2.60-53.26), SE 40.0%, SP 94.6%, PPV40.0% and NPV 94.6%. Lowering the cutoff to low grade squamous intraepithelial lesions increased SE and NPV but compromised SP and PPV. The detection rates for high grade lesions after an atypical squamous cells of undetermined significance diagnosis were similar with the 3 techniques. Conclusion In our settings, the 3 methods of cervical cytology were slightly different in performance. The conventional Pap smear had the highest SE, while Autocyte (R) PREP had 100% SP and PPV in detecting CIN 3 with the HSIL cutoff. All 3 tests had lower SE but higher SP as compared to HCH.