Comparative evaluation of smear cytology & hybrid capture II for the diagnosis of cervical cancer

Background & objectives: There is no ideal screening method for cervical cancer in India with the role of human papilloma virus (HPV) detection yet to be established. This study was undertaken to compare the diagnostic accuracy of HPV testing by hybrid capture II (HC-II) with conventional cervical smear cytology for squamous intraepithelial lesions (SIL). Methods: This prospective study was conducted at New Delhi during 2003-2004 with patients selected from the gynaecology out patients of the All India Institute of Medical Sciences. Initial screening by a questionnaire and per-speculum examination were used to select high-risk patients. Patients, in whom conventional cytology, HC-II test and colposcopy-directed biopsy were done, formed the basis of this study. Results: Of the 133 patients included in the study, incidence on biopsy of low grade SIL (L-SIL) was 6.77 per cent, high grade SIL (H-SIL) was 8.27 per cent and carcinoma was 3.00 per cent. Sensitivity and specificity of cytology for detection of H-SIL and above lesions was 93.33 and 83.49 per cent while for HC-II it was 93.33 and 90.83 per cent, respectively. HC-II had higher diagnostic accuracy of 91.13 per cent versus 84.68 per cent for cytology. Kappa for HC-II was higher (0.67) than cytology (0.52). Among patients diagnosed to have atypical squamous cells (ASC-US & ASC-H) and L-SIL, HC-II helped to select patients who had significant lesions on biopsy. Interpretation & conclusion: The main utility of HC-II is in the triage of patients with cytology smear diagnosis of ASC-US, ASC-H or L-SIL, for referral to colposcopic examination. HC-II alone has the best diagnostic accuracy but owing to high cost it is unsuitable for general screening in developing countries. Combining HC-II with cytology will refer smaller numbers for colposcopy, improving efficient utilization of available resources