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Cervical Screening

HPV testing: The detection of DNA, RNA or protein from high-risk, cancer-causing HPV types is increasingly being used to screen for the presence of the virus.  HPV DNA testing is most common, and there are several platforms that support this.  The HPV DNA test sample has historically been taken in the same way as the Pap smear, during a speculum examination.  However many studies have now shown that a vaginal sample taken with a swab is a similarly effective means of sampling.  There are also now a number of studies that show a self-collected vaginal sample is suitable for this type of test.  Self-sampling has benefits in the context of cervical screening in the Pacific, enabling community-based screening at 'point-of-care' and overcoming barriers of shyness and discomfort that prevent some women from being screened.

The 'Pap' test: The Pap test (or Pap smear) was developed in the 1930's by George Papanicolaou.  The cells of the cervix are gently scraped with a special brush during a speculum examination.  The sample is smeared onto a slide and stained.  A trained Cytopathologist examines the slide under the microscope and looks for changes to the cells that are characteristically pre-cancerous (dysplasia - not cancer but more likely to progress to cancer) or cancerous.  The key results are reported as normal (healthy cervix), a 'low grade squamous intraepithelial lesion', or LSIL (indicates HPV infection, needs to be monitored) or high grade squamous intraepithelial lesion' or HSIL (indicates an increased likelihood of progression to cancer).  This test may also detect changes that are of unknown significance (ASCUS) or squamous cell carcinoma. 

VIA (Visual Inspection with Acetic Acid):  Application of acetic acid (vinegar) to the cervix causes cervical dyplasia (pre-cancer) lesions to go white.  This method is used to guide treatment, but has also been used as a primary screening tool in low resource settings.  Benefits of VIA are its cost, and that the testing and treatment is carried out in one visit (reduced risk of loss to follow up).  However the test is less specific than the Pap smear, and is more prone to false positives.  Several studies have now shown that HPV testing is more accurate, sensitive and robust than VIA.

Cervical Cancer Screening in the Pacific:  An overview of cervical cancer screening practices in the Pacific region has been reported by Obel, et al (2015) and is available via PubMed.