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Diagnosing HPV Infection, Genotyping
& Cervical Cancer
Invasive squamous carcinoma of the cervix results from the progression of preinvasive precursor lesions called Cervical Intraepithelial Neoplasia (CIN), or dysplasia. CIN is histologically graded into mild dysplasia (CIN 1), moderate dysplasia (CIN 2), or severe dysplasia (CIN 3). Not all of these lesions progress to invasive cancer. The rate at which invasive cancer develops from CIN is usually slow. This long natural history provides the opportunity for screening to effectively detect this process during the preinvasive phase, thus allowing early treatment and cure.
The leading etiologic factor in the development of preinvasive and invasive cervical cancer is infection with specific types of Human Papillomavirus (HPV), transmitted by sexual contact.
95% of women with invasive cervical cancer have evidence of HPV infection. 10% to 20% of women with (CIN 3) lesions progress to invasive cancer.
What are HPVs, and how are they transmitted?
Human Papillomaviruses (HPV) are a group of more than 100 viruses. They are called papillomaviruses because certain types may cause warts, or papillomas. The HPVs that cause the common warts which grow on hands and feet are different from those that cause growths in the throat or genital area. More than 30 types of HPV are Sexually transmitted.
How can HPV cause cancer?
Some types of HPV are referred to as “low-risk” viruses because they rarely develop into cancer. HPV types that are more likely to lead to the development of cancer are referred to as “high-risk.” Both high-risk and low-risk types of HPV can cause the growth of abnormal cells. High-risk include types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 69, and possibly a few others. Studies suggest that acute infection with HPV types 16 and 18 results in an 11-17 fold risk of rapid development of high-grade CIN.
How can cervical screening & diagnosis of HPV reduce cervical cancer?
Based on solid evidence, regular screening of appropriate women for cervical cancer with the Papanicolaou (Pap) test reduces mortality from cervical cancer through the early diagnosis of precancerous lesions. Screening is effective when started within 3 years after first vaginal intercourse. Testing samples of cervical cells is an effective way to identify high-risk types of HPV that may be present. This test, which looks for viral DNA, can detect high-risk types of HPV even before there are any conclusive visible changes to the cervical cells.
Indications for HPV screening & genotyping?
The FDA has approved an HPV test as a follow-up for women who have an ambiguous Pap test and for women over the age of 30, for general cervical cancer screening.
Diagnosis of HPV (new)
Al Borg lab has recently introduced PCR for HPV diagnosis and HPV genotyping. Both techniques are sensitive, specific detecting 35 HPV genotypes. Detection and interpretation of results is fully automated using a patented array tube with workstation powered by specific software.
Material eligible for performing the test?
The test can be performed reliably on cervical swabs (stored at 4oC for 7 days), liquid cytology (cell suspension in a transport medium), formol-fixed paraffin-embedded tissues (fixation in neutral 10% formalin not for more than 24 hours).
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