Utility of extended HPV genotyping in cervical cancer screening and clinical management

Cervical cancer is the fourth most common cause of death among adult women worldwide, with persistent infection by high-risk human papillomavirus (HR-HPV) recognised as the primary pathogenic factor.1 Approximately 30 HPV genotypes are known to infect the cervical mucosa, with 14 of these, including HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 and 68, classified by the WHO. Notably, HPV 66, previously considered carcinogenic, has now been reclassified as a non-carcinogen. Consequently, the International Agency for Research on Cancer (IARC) categorises the remaining 13 HPV genotypes into four groups based on their carcinogenic potential: HPV 16, HPV 18/45, HPV 16-related genotypes (HPV 33, 31, 52, 58 and 35) and other potentially carcinogenic genotypes (HPV 39, 51, 59, 56 and 68). The majority of the published literature focused on these 14 HR-HPV genotypes, as well as HPV 73, 82, 26 and 53. It is well established that HPV 16 and 18 exhibit the highest carcinogenicity, accounting for more than 70% of cervical cancers and precancerous lesions. Recent studies have also begun to recognise the role of other HPV genotypes in the development of cervical disease.

Given the critical role of HPV infection in cervical lesions, HPV testing has become the preferred method for primary cervical cancer screening in the 2020 American Cancer Society and the 2019 American Society for Colposcopy and Cervical Pathology (ASCCP) consensus guidelines.2 3 Triage strategies for positive HPV testing results include options such as dual p16/Ki-67 immunohistochemical staining, methylation testing and extended HPV genotyping.3 Recently, the Enduring Consensus Cervical Cancer Screening and Management Guidelines Committee developed recommendations for using extended genotyping results in cervical cancer prevention programmes, based on clinical action thresholds established by the 2019 ASCCP consensus guidelines.4 Three main triage strategies are recommended: (1) colposcopy is advised for individuals who test positive for HPV 16 and 18, in alignment with the 2019 ASCCP guidance; (2) for those who test positive for HPV 45, 33/58, 31, 52, 35/39/68 or 51, cytology or dual p16/Ki-67 immunohistochemical staining is recommended as part of the triage process; (3) when screening with the primary HPV test, repeat HPV testing after 1 year is recommended for patients who test positive for HPV 56/59/66. For patients undergoing cotesting, patients with HPV 56/59/66-positive results and cytological results reported as negative, atypical squamous cells of undetermined significance (ASC-US) or low-grade squamous intraepithelial lesions (LSILs) should be screened again in 1 year. For patients with atypical squamous cells who cannot exclude high-grade squamous intraepithelial lesion (ASC-H), atypical glandular cells (AGC), high-grade squamous intraepithelial lesion (HSIL) or carcinoma, colposcopy is recommended. The recommendation also notes that for patients with multiple HPV genotypes detected, management should be based on the type with the highest cancer risk according to the IARC scale. However, this consensus applies only to US Food and Drug Administration (FDA)-approved extended genotyping assays, specifically the Onclarity HPV testing assay. Current FDA-approved extended genotyping assays do not fully conform to the IARC HPV groupings. For instance, while HPV 35 is categorised as an HPV 16-related type according to the IARC carcinogenicity ranking, and HPV 39 and HPV 68 are considered lower risk, the Onclarity HPV assay groups HPV 35 39, and 68 are combined together in the same category.

The recommendation presented here is primarily based on data from a few clinical trials or studies from countries with high screening rates and has been specifically developed for the USA. Extended HPV genotyping methods are rarely used clinically in the USA now. Data from studies in China differ significantly due to variations in race, screening rates, geographic regions and HPV testing assays. For instance, significant differences have been noted in the distribution of HR-HPV genotypes. HPV16, HPV18 and HPV45 are by far the most common and most oncogenic genotypes in the USA and European countries, whereas HPV16, HPV58 and HPV52 are more prevalent in China and Asian countries, especially in squamous lesions.5–8 And then, there are numerous China National Medical Products Administration-approved HPV testing assays from various companies, in addition to the assays approved by the US FDA. It is estimated that there are approximately 40 types of HPV full genotyping products available, covering a broader range of genotypes, including the 14 HPV genotypes recognised by the WHO as well as HPV types 73, 82, 26 and 53. Full genotyping offers a more comprehensive and objective approach compared with extended genotyping, providing greater detail regarding HPV genotyping-associated risks. Recently, a review article summarised studies on the relationship between various HR-HPV genotypes and the highest risk for CIN2+ or CIN3+ lesions across different cytological outcomes.9 Specific HPV genotypes have been shown to significantly improve the accuracy of predicting CIN2+ lesions among normal or mildly abnormal cytological results in large-scale studies of the Chinese population from different regions (table 1). The CIN2+ detection rate for HPV16/18/45 (11.5%; 14/122 cases) was higher than that for the HPV16/18/45-negative genotypes (3.6%; 7/196 cases) in cytologically negative cases.10 The top 5 HPV genotypes associated with the highest risk for CIN2+ in ASCUS cases were HPV16/18/31/33/58, 16/33/82/18/31, 16/31/35/45/82, 16/18/33/51/52 and 16/58/18/33/31 from different studies.11–15 Two studies have proposed a genotyping model, HPV16/26/82/31/18/33/58/35/52/51 and HPV 16/18/31/33/52/58, which has shown excellent efficacy in the detection of CIN2+ lesions in LSIL cases.16 17 Tang et al reported the increasing risk of CIN2+ for the composite group of HPV16/18/58/52/53-positive cases among AGC cases.18 These results reveal that HPV 31, 33, 58 and 52 are most frequently associated with higher risks for cervical HSIL lesions after HPV 16 and 18. While HPV 45 is strongly linked to adenocarcinoma, its association with high-grade squamous lesions is not as pronounced as it is with cervical cancer. Interestingly, HPV 82, which is not included in the US FDA-approved HPV assay, has been reported to carry a higher risk for HSIL+ in ASCUS and LSIL even though the positivity rate is low. The study by Dun et al reached a similar conclusion, showing that women with positive HPV genotyping for types 16/18/58/33/31 had a sufficiently high risk for CIN3+ to warrant a referral for colposcopy.19 Conversely, women with negative tests had a risk below the 1-year return threshold, according to internal benchmarks. Additionally, the ASCCP guidelines are based on risk, which considers both current screening results and medical history. This approach may not be as applicable in many developing countries, including China, which are facing logistical and infrastructure inadequacies, high costs, difficulties in patient follow-up and sociocultural constraints. To address this gap, Dong et al developed a machine learning model that provides a new risk prediction tool for cervical cancer screening based on full genotyping data for HR-HPV.20 The final simplified clinical risk prediction model included the following factors: HR-HPV, the number of HPV genotypes, cervical cytology, HPV types 16, 18, 52 and 39, age and gynaecological examination. The XGBoost model demonstrated strong discriminant and calibration performance in predicting CIN2+ and CIN3+. Xiao et al also built a cervical cancer diagnostic prediction model for women with HR-HPV infection, which is a stacking machine learning model that included epidemiological factors, pelvic examination results, and HPV genotypes predicted CIN3+ and CIN2+ well.21 The developed prediction model using HPV genotyping may be a practical tool for cervical cancer screening in the future, especially in low-resource settings.

Traditional HPV tests primarily focus on the most common high-risk genotypes, namely HPV 16 and 18. However, further research has revealed that other HR-HPV genotypes, such as HPV 31, 33, 52, and 58, also play a significant role in the development of cervical cancer, particularly in regions such as China and other parts of Asia. These findings have led to the increasing use of HPV-extended or full genotyping in cervical cancer screening. HPV-extended genotyping allows for more precise identification of high-risk groups, improving the specificity and negative predictive value of screening. This approach can reduce unnecessary medical interventions and alleviate both the financial and psychological burdens on patients. Furthermore, with the widespread use of HPV vaccines, the infection rates of HPV 16 and 18 are gradually declining, while the rates of infection with other high-risk HPV types may rise. As a result, HPV-extended or full genotyping is becoming better suited to monitor these changes, providing a more effective tool for cervical cancer screening in the postvaccination era.