EPIDEMIOLOGY OF HIGH-RISK HPV GENOTYPES AND THEIR CLINICAL CORRELATES WITH CERVICAL CYTOLOGY IN EASTERN BULGARIA: A RETROSPECTIVE STUDY

Abstract

Cervical cancer (CC) remains a major public health problem, ranking as the fourth most common malignancy among women worldwide. Persistent infection with high-risk (HR) human papillomavirus (HPV) (HR-HPV) genotypes is the principal etiological factor in the development of cervical intraepithelial neoplasia (CIN) and cervical carcinoma. More than 200 HPV genotypes have been identified, of which at least 13 are classified as HR (highly oncogenic). HPV 16 and 18 alone account for approximately 70% of the CC cases globally. The prevalence and distribution of HPV genotypes vary substantially by geographic region, age, socioeconomic factors, and screening practices. Regional characterization of HPV epidemiology is therefore essential for tailoring vaccination programs, screening strategies, and follow up guidelines. Objective: To evaluate the frequency and association between HR-HPV infection and cervical cytological abnormalities and to describe HPV genotype distribution in a screened population. Materials and Methods: The retrospective analysis included 190 women aged 15-60 years who underwent routine CC screening. Patients with incomplete medical records or a history of treatment for CIN were excluded. All the patients underwent liquid-based cytology and HPV genotyping (only HR oncogenic HPV strains were tested; patients with low risk HPV types were not included).  Results: Of the 190 patients included in the study, 65 tested positive for HPV, yielding an overall infection rate of 34.2%. Our analysis found that the number of patients tested for HPV increased over the years: from 22 tests in 2022 to 58 in 2025. Among 190 patients, 125 (65.8%) were HPV-negative and 65 (34.2%) HPV-positive. The rate of abnormal cytology was 26.32% (50/190), and the overall prevalence of HR-HPV positivity was 34.2% (65/190). In our cohort, of the 50 patients with abnormal cytology, 38 were HR-HPV-positive, while among 140 patients with normal cytology, 113 were HR-HPV-negative. The HR-HPV types detected in our cohort were mainly 16, 66, 45, 51, 52 and 53. The frequency distribution was as follows: HPV 16 – 10% (19/190), 66 – 4.74% (9/190), 45 – 4.74% (9/190), 52 – 4.21% (8/190), and HPV 51 and 53 – 3.68% (7/190) each. Of the 65 HPV-positive patients, 61.54% (40/65) had a single HR-HPV type infection and 38.46% (25/65) had multiple HR-HPV infections. In the 20-29-year age group, two patients were positive for five different HR-HPV types. A chi-square test was used to assess the association between single and multiple infections. Multiple infections were recorded when more than one HR-HPV genotype was detected in the sample. Conclusion: The present study confirms a strong association between HPV infection and abnormal cervical cytology, supporting the established role of HPV as a major factor in the development of CIN. Women with a positive HPV result had a six-fold increased risk of cytological abnormalities, consistent with findings from global meta-analyses. Based on the analysis of HR-HPV infection in exfoliated cervical cells from 190 gynecological patients in our clinic in Eastern Bulgaria, we draw the following conclusions: from 2022 to 2025, the overall prevalence of HR-HPV infections showed an increasing trend. Rates of single and multiple HR-HPV infections peaked among young women. Single infections remain the predominant form of HPV infection, with the most common HR genotypes being HPV 16, 66, 45, 52, 53 and 51. HR-HPV type 33, which is included in current HPV vaccines, was not detected in the studied population. In our study, HR-HPV-positive women were 6.5 times more likely to have abnormal cervical cytology.