Quality Assurance in Cervical Cancer Screening: Evaluation of Sample Adequacy in HPV DNA Testing

ABSTRACT

In HPV‐primary screening, sample quality significantly influences test accuracy. Unlike cytology‐based screening, no consensus guidelines presently exist for sample quality assessment in HPV testing. This study aims to evaluate the impact of sample cellularity on HPV testing. A total of 37 592 liquid‐based cytology (LBC) samples from women undergoing HPV‐primary screening (aged 30–64, median 48; IQR: 40–56 years) were analyzed using Cobas 4800 HPV Test (Roche). Sample adequacy was assessed by the assay's β‐globin internal control and by an independent quantitative cellularity assessment (OncoPredict HPV, Hiantis). HPV positivity rates (PR) were stratified according to β‐globin Ct values. Among the analyzed samples, 50.0%, 47.1%, 2.3%, and 0.6% had β‐globin Ct values of ≤ 28, > 28 to ≤ 32, > 32 to ≤ 34, and > 34, respectively. Overall HPV‐PR was 7.7% (2891/37 592). PR reached 9.7% in samples with β‐globin ≤ 28 Ct (1820/18 801), decreasing markedly to 1.4% for β‐globin > 34 Ct (3/214), (p < 0.001). Quantitative analysis showed that Cobas 4800 β‐globin Ct = 34 corresponds to approximately 1.5 × 10^3 nucleated cells/reaction. A subset of 195 HPV‐negative samples with β‐globin Ct ≥ 34 was evaluated by liquid based cytology (LBC): 19% had inadequate cellularity according to LBC guidelines, 8% were ≥ ASC‐US and 73% NILMs. 65% of adequate LBC showed cellular atrophy. These findings emphasize the importance of assessing cellularity in HPV‐screening to avoid potentially false‐negative results due to inadequate samples. Future research should focus on establishing standardized cellularity thresholds to improve screening accuracy.