Persistent infection with high-risk HPV is the primary cause of cervical cancer and precancerous lesions. However, most HPV infections are asymptomatic or subclinical and can only be identified through HPV nucleic acid testing. HPV nucleic acid testing plays a critical role in cervical cancer screening and follow-up.
Methods of HPV Nucleic Acid Testing
The widespread adoption of HPV nucleic acid testing has been facilitated by advancements in detection techniques. In 1999, the first HPV DNA test kit employing hybrid capture technology (hybrid capture 2, HC2) received FDA approval in the United States. Regardless of the detection technology used, the primary purpose of HPV testing is not to diagnose the presence of viral infection, but to predict the likelihood of cervical precancerous lesions or early invasive cancer. According to the NMPA's 2015 standards, testing is conducted for 13 high-risk HPV genotypes (HPV16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). Based on the target gene fragment, testing can be categorized into HPV DNA testing and HPV RNA testing. Furthermore, tests can be classified into non-genotyping, partial genotyping (HPV16 and HPV18), and full genotyping.
Based on detection principles, nucleic acid testing is divided into amplification and non-amplification techniques. Non-nucleic acid amplification techniques include hybrid capture, which detects HPV by amplifying the chemiluminescent signal from the viral genomic sequence, and enzyme signal amplification methods, which use molecular hybridization and chemical signal amplification to directly detect specific HPV DNA sequences. Nucleic acid amplification techniques are categorized into DNA and RNA amplification based on the target gene fragment. Amplification methods include PCR-based techniques (conventional PCR, real-time quantitative fluorescence PCR, PCR-reverse dot blot hybridization, fluorescence PCR-melting curve analysis, PCR-microfluidic chip analysis, PCR-flow fluorescence hybridization, among others) and transcription-mediated isothermal amplification.
In addition, pathological examination combined with in situ hybridization is a technique that involves hybridizing molecular probes with HPV DNA on pathological tissue or cytological slides. This method allows the observation of histological changes while simultaneously determining HPV genotypes. It is an ideal technique for pathological detection and research, though unsuitable for large-scale screening.
Clinical Applications of HPV Testing
With the accumulation of robust clinical evidence from high-quality studies, HPV nucleic acid testing has become increasingly important in cervical cancer screening and follow-up.
HPV Testing as a Standalone Primary Screening Tool for Women Aged 25 and Older
This is the preferred cervical cancer primary screening method for healthy populations. It offers high sensitivity and is not influenced by subjective factors. However, a positive HPV result does not equate to the presence of precancerous lesions. Triage using cytology, partial genotyping for HPV16/18, or other high-specificity methods is necessary to avoid excessive testing and overtreatment.
HPV Testing Combined with Cytology for Primary Cervical Cancer Screening
The high specificity of cytological testing compensates for the low specificity of HPV testing, while the high sensitivity of HPV testing reduces the likelihood of false-negative results in cytology. The combination of these methods provides complementary advantages and is suitable for hospital-based populations or regions with abundant financial resources and medical infrastructure.
HPV Testing for Triage of ASC-US Cases in Cytology Screening
This application reduces the burden of over-diagnosis and overtreatment on both patients and physicians.
HPV Testing for Monitoring Clinical Outcomes and Follow-Up After Treatment for Cervical Precancerous Lesions or Cancer
When HPV testing remains persistently positive after treatment, it may indicate residual lesions or potential recurrence, requiring close monitoring.