Human papillomavirus viral load expressed as relative light units (RLU) correlates with the presence and grade of preneoplastic lesions of the uterine cervix in atypical squamous cells of undetermined significance (ASCUS) cytology.

Human papillomavirus (HPV) testing is more sensitive and has higher negative predictive value (NPV) than the Pap test for the detection of cervical intraepithelial neoplasia (CIN) in patients with atypical squamous cells of undetermined significance (ASCUS) cytology, but has low specificity, leading to high referral rates to second-level triage. Our goal was to identify the prognostic significance of HPV viral load figures. We evaluated whether a correlation between viral load, expressed as relative light units/cutoff (RLU/CO), and the severity of cervical lesions existed in 614 ASCUS cases. Hybrid Capture 2 (HC2®) RLU/CO values, categorised into five classes, were correlated to clinical outcomes and statistically analysed. A significant correlation (p < 0.0001) was observed between increasing RLU values and the prevalence of high-grade CIN (CIN2/CIN3). The mean RLU values for negative, low-grade and high-grade lesions were 68.1, 172.5 and 1,020.0 RLU/CO, respectively (p < 0.0001). CIN2/CIN3 ranged from 4% for 0 < RLU/CO values ≤ 1, to 5% for 1 < RLU/CO values ≤ 10, to 9% for 10 < RLU/CO values ≤ 100, to 23% for 100 < RLU/CO values ≤ 1,000 and to 48% when RLU/CO values were >1,000 (p < 0.05). The HPV viral load in ASCUS cases significantly correlates with the severity of cervical cancer precursors. These data may have prognostic value, as they significantly correlate with the probability of a CIN2+ .