Human Papillomavirus (HPV)
Cervical cancer is the second most common cancer in women after breast cancer.
14 high risk HPV genotypes contribute to the majority of cervical cancer cases. The main reasons for the higher incidence and mortality in developing countries are lack of awareness of cervical cancer among the population, lack of screening programs, and limited access to health care services.
According to data from WHO, the number of women at risk for cervical cancer is over 2 billion, primarily in developing worlds. The number of cervical cancer rates and deaths is projected to almost double by 2025.
WHAT IS HPV ?
Human Papillomavirus (HPV) is a small, non-enveloped, double-stranded DNA virus (approximately 8,000 base pairs) that replicates in the nucleus of squamous epithelial cells and induces hyperproliferative lesions. HPV infections are among the most common sexually transmitted infections.
Most HPV infections have a benign clinical consequence and are cleared spontaneously. However, persistent HPV infection may result in progression to cervical cancer. More than one hundred different HPV genotypes have been identified, among which over forty infect mucosal and genital epithelia. Genital HPV genotypes are generally classified into high risk (HR) and low risk (LR) groups based on their carcinogenic potential.
HR HPV genotypes are associated with invasive cervical cancer or its immediate precursor (high-grade squamous intraepithelial lesion, cervical intraepithelial neoplasia or carcinoma in situ), whereas LR HPV genotypes include benign lesion and are not associated with cervical cancer. Approximately 70% of invasive cervical cancer cases worldwide are caused by HPV 16 and HPV 18.
Infection by HPV 16 or HPV 18 is associated with higher risk of disease progression compared to other HR HPV genotypes. Compared with cervical screening methods identifying cytological abnormalities, molecular tests that specifically detect the presence of HR HPV DNA in cervical cells can potentially increase sensitivity and cost-effectiveness of cervical cancer screening programs. Furthermore, HPV DNA tests can be effectively used in triaging patients with equivocal cytology, in post-therapeutic follow-up and in monitoring vaccine efficacy.
The RealTime High Risk (HR) HPV DNA assay is a qualitative in vitro test that amplifies and detects HR HPV DNA in cervical cells collected in liquid media. The detection of fourteen HR HPV genotypes (HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68) is achieved through a primer mix targeting a conserved region of HPV genomes and single-stranded DNA probes. The assay can differentiate between HPV 16, HPV 18 and non-HPV 16/18 genotypes (Other HR HPV).
Specimen Collection and Handling
Specimens collected in Liquid Cytology Pap Test solution can be used. Cervical specimens collected in Liquid Cytology Pap Test solution (universal specimen medium) can be transported at 2 ‘C to 30 ‘C and may be stored for up to 14 days at 2 ‘C to 30 ‘C or up to 90 days at -10 ‘C or colder following collection.
Specific key messages to patients receiving cervical screening:
- The purpose of regular, lifelong cervical cancer screening is to identify cervical cancer precursors, which can be treated before progression to cervical cancer.
- A positive high-risk HPV DNA test or an abnormal cervical cytology test is not indicative of cervical cancer.Appropriate follow-up is necessary to ensure that cervical abnormalities do not progress.
- Some women might have a normal Pap test and a positive high-risk HPV test. A positive high risk HPV DNA test indicates a HPV infection of the cervix, but does not indicate cervical cancer.A normal cervical cytology test indicates that no cellular abnormalities were detected at the time of testing, but women who have HPV infection of the cervix have a higher likelihood of developing cell changes, which could lead to cervical cancer over time. Follow-up evaluation is essential to monitor cervical cytology.
- A Pap test that reveals ASC-US (atypical squamous cells of undetermined significance) indicates some abnormal areas on the cervix that may require close follow-up or treatment so that they do not progress. Additional testing might be required to confirm these results. It is essential that patients return for all follow-up appointments and recommended tests.
- HPV is very common. It can infect the genital areas of both men and women. It usually has no signs or symptoms.
- Most sexually active persons get HPV at some time in their lives, though most will never know it. Even persons with only one lifetime sex partner can get HPV if their partner was infected
- While the immune system clears HPV infection most of the time, in some persons, HPV infection does not resolve.
- No clinically validated test exists for men to determine if they have HPV infection. The most common manifestation of HPV infection in men is genital warts. High-risk HPV types seldom cause genital warts.
- Partners who are in a long-term relationship tend to share HPV. Sexual partners of HPV-infected patients also likely have HPV, even though they might have no signs or symptoms of infection.
- Detection of high-risk HPV infection in a woman does not mean that the woman or her partner is engaging in sexual activity outside of a relationship. HPV infection can be present for many years before it is detected, and no method can accurately confirm when HPV infection was acquired.