Pap Smear or HPV Testing for Cervical Cancer?

By Jeffrey Norris, UCSF Science Cafe | April 9, 2009

Cervical cancer screening and follow-up might one day come to the rural US via a mobile van. Or at least one might imagine such a scenario after reading a study published in the April 2 issue of the New England Journal of Medicine (NEJM).

Cervical cancer may be caused by any of more than a dozen particular strains of sexually transmitted human papillomavirus, or HPV. The NEJM study of more than 130,000 women found that one-time screening and follow up using a DNA test to detect HPV strains associated with cervical cancer resulted in fewer cervical cancer deaths in later years in comparison to other screening methods, including the familiar "Pap" smear used to detect abnormal cells.

The study, funded by the Bill and Melinda Gates Foundation, took place in India and included women between the ages of 30 and 59. Cervical cancer is common in developing countries, such as India, where few women have access to routine screening in comparison to most women in the United States. The study aimed to see if low-cost, one-time screening and immediate follow-up had any long term benefit over no screening.

The answer appears to be yes. Women screened for either HPV or abnormal cells had fewer cervical cancers in the following years, compared to unscreened women. However, cervical cancer deaths appeared to be significantly reduced only among women screened with the HPV test.

According to the researchers who conducted the study, "The reduction in the incidence of advanced cancers and deaths associated with HPV testing probably reflects the higher sensitivity of HPV testing to detect lesions with a high potential for malignant transformation than that of cytologic testing...."

George Sawaya, MD, a UCSF gynecologist and epidemiologist who studies the costs and benefits of screening strategies, finds that explanation intriguing, but wonders if the failure to demonstrate fewer cervical cancer deaths among women screened with Pap smears was due to less-experienced cytologists interpreting Pap smears in comparison to cytologists working in US clinical labs.

Read more at Jeffrey Norris, UCSF Science Cafe