When a Pap Smear Just Isn’t Enough

HPV test may help diagnose abnormal Pap smear as cervical cancer

(RxWiki News) If Pap smear results come back as abnormal, don't panic. An HPV test might help shed a little light on what exactly "abnormal" means for some tests.

A recent study looked at the effectiveness of lab testing for cervical cancer from Pap smear samples.

The results of the study showed that a DNA test for human papillomavirus (HPV) may help detect one of two potentially cancerous cells in the cervix.

"Ask for an HPV test instead of a repeat Pap smear."

Marc Arbyn, MD, from the Unit of Cancer Epidemiology at the Scientific Institute of Public Health in Brussels, Belgium, led an investigation into two different types of tests that screen for cervical cancer.

For this study, 39 previous studies that included 13,196 women were selected to compare test results of cervical cancer screening tests.

All of the women in the study were given Pap smears to test for precancerous cervical cells or lesions.

The studies looked at the accuracy of two different types of lab techniques used to test Pap smear samples: the Hybrid Capture 2 High-Risk HPV DNA Test (HPV test) and cytology.

HPV is a risk factor for cervical cancer, and testing for the virus with the HPV test could point to whether a woman could really be at risk for cervical cancer.

Cytology is done by a trained lab technician who looks through a microscope at the cells taken from the Pap smear for anything out of the ordinary.

Two types of cervical cell abnormalities are atypical cells of undetermined significance (ASCUS) and low-grade squamous intra-epithelial lesions (LSIL).

Typically, after a woman gets a Pap smear, the results are sent to a lab for cytology. If the cytology results are abnormal, another Pap smear is done, which gets sent to the lab for another cytology.

This process can continue for multiple tests and is called “repeat cytology.” Abnormal test results do not necessarily mean pre-cancer. More expensive and invasive tests are available to help determine whether cervical cells are precancerous. These tests include colposcopy and biopsy. 

The results of the study showed that the HPV test was 91 percent accurate at finding moderately serious lesions and 95 percent accurate at finding very serious lesions in patients with ASCUS cells.

But the HPV test was only 71 percent accurate at finding moderately serious lesions and 57 percent accurate at finding very serious lesions in patients with LSIL cells.

The authors recommended that women with ASCUS-type lesions have an HPV test, while women with LSIL-type lesions might need repeat cytology, or colposcopy and biopsy, if those are accessible.

This study was published in March in The Cochrane Library.

The Cochrane Gynaecological Cancer Review Group, the European Commission, the International Agency for Research on Cancer, the Belgian Foundation Against Cancer and other public and private institution, agency and foundation funding was used for external support of this project. No conflicts of interest were declared.

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Review Date: 
March 25, 2013