HPV testing for cervical cancer screening: Should reflex cytology be performed after a positive test for HPV 16 and 18?

At Portuguese-organized cervical cancer (CC) screening programs, all women testing positive for human papillomavirus (HPV) 16 and/or 18 are referred for immediate colposcopy. This study aimed to evaluate the utility of reflex cytology in women who test positive for HPV 16 and/or 18 to improve the efficiency of CC screening. A cross-sectional and retrospective study was performed based on data from the routine CC screening protocol in force at Cova da Beira University Hospital Center, Portugal between August 2012 and June 2021. The screening method was the Cobas 4800 HPV test using the liquid medium Surepath. In all the selected cases, the patient's HPV test results and the cytology and histology findings of the biopsies obtained using colposcopy were analyzed. This study included 339 women who first tested positive for HPV 16 and/or 18 and were referred for immediate colposcopy, in whom 40 (11.8%) cases of high-grade squamous intraepithelial lesion (HSIL+) were diagnosed. Of these, 12 (30%) had reflex cytology negative for intraepithelial lesion or malignancy (NILM) and 14 (35%) had HSIL+ cytology. After 3 years, 14 (9.3%) of the 150 women who were still undergoing follow-up were diagnosed with histologic HSIL+ lesions, of which 5 (35.7%) had baseline NILM cytology. Despite the small sample, the results of this study allow us to conclude that reflex cytology is not useful for discrimination to immediate referral for colposcopy in women who test positive for HPV 16 and/or 18, as most women with a histologic diagnosis of an HSIL+ lesion had <HSIL reflex cytology.