Adjunctive testing for cervical cancer screening in low resource settings

Cervical cancer screening using cytology is expensive and requires repeat testing with loss to follow-up for triage. Adjunctive testing using two tests in a parallel or sequential combination can improve diagnostic accuracy, decrease costs and minimise referral rates.

To evaluate the performance of visual inspection with acetic acid (VIA), human papillomavirus (HPV) DNA and cervical cytology in sequential and parallel combinations, to determine the optimum screening strategy.

A total of 548 symptomatic women presenting to a gynaecology clinic were screened using conventional cytology; HPV testing of self- and physician-collected samples using HC2 assay; and VIA. All women underwent colposcopy with biopsy from all lesions as the reference standard. Test characteristics were calculated individually, and then applied jointly in parallel and sequential combinations.

Biopsy-proven CIN2+ was present in 40 (7.8%) women. The sensitivity and specificity, respectively, of the various tests were as follows - VIA 82.5, 66.9%, Pap (≥ASCUS) 77.5, 86.8%, HPV-Physician (HPV(P)) 90.0, 91.5%, HPV-Self (HPV(S)) 80.0, 88.1%. Among the adjunctive testing scenarios, sequential testing performed better than parallel. VIA followed by HPV test had the highest specificity (90.4%) and diagnostic accuracy (90.5%), comparable to HPV-P followed by Pap.

Sequential testing combination of VIA and HPV, followed by colposcopy and directed biopsy for diagnosis, combines economic viability with high scientific fidelity. The high specificity and negative predictive value reduce referral and treatment rates, as well as number of visits required for diagnosis. HPV (P) followed by reflex Pap is a suitable option for high resource situations with access to liquid-based cytology.