Monday, September 17, 2018

Cervical cancer screening in the age of HPV vaccination

- Jennifer Middleton, MD, MPH

A POEM (Patient-Oriented Evidence that Matters) in the current edition of AFP suggests the potential for change in cervical cancer screening practices; screening younger women only with human papillomavirus (HPV) testing, and not cytology, resulted in better identification of high grade pre-cancerous disease in individuals who have received the HPV vaccine.

This study from Australia enrolled nearly 5,000 women aged 25-64 presenting for cervical cancer screening to one of three groups: liquid-based cytology screening followed by HPV testing if abnormal, HPV screening followed by liquid-based cytology as indicated, or HPV screening followed by dual-stained cytology (staining for high-risk HPV markers) as indicated. At the time of the study, women 33 years old or younger had been eligible to receive the HPV vaccine when it was first available in Australia; in these women, both of the HPV screening groups had a higher rate of pre-cancerous disease detection than the cytology-based screening group.

The United States Preventive Services Task Force (USPSTF) currently recommends HPV screening every 5 years as an option only for women aged 30 and older along with screening every 3 years with cytology alone or screening every 5 years with cytology and HPV co-testing; they recommend discussing risks (HPV screening alone and HPV/cytology co-testing both have an increased rate of false positive screening results, while cytology alone may miss some true positives) of each method with individuals to personalize screening decisions. For women aged 21-29, the USPSTF only recommends cervical cancer screening with cytology alone every 3 years. The American College of Gynecology and Obstetrics does not allow for the option of HPV testing alone for women of any age, but otherwise their recommendations align with the USPSTF.

HPV vaccine acceptance and uptake has been quite high in Australia, with the study authors citing that 70-78% of women aged 12-17 years were fully vaccinated in 2013. In the United States, HPV vaccine uptake has been less successful; the Centers for Disease Control (CDC) estimates that half of US teens have not completed the HPV series (you can find specific data for your state using this interactive map). It's possible that this POEM's findings may not be generalizable to the US given this difference in vaccination rates, but studies have also supported the sole use of HPV screening in women who were beyond vaccination age when HPV vaccine was introduced in the US.

Regardless, HPV vaccination rates have plenty of room for improvement in the US. Barriers to increasing HPV vaccination in the US, as outlined in this 2016 AFP Community Blog post by Dr. Lin, include safety concerns and parental worry about the vaccine encouraging earlier initiation of sexual activity (it doesn't). Physicians, too, are sometimes reluctant to discuss or recommend the vaccine. Strategies to overcome these barriers include reviewing vaccinations at every visit (not just well visits) as recommended by the authors of this 2015 AFP editorial on "HPV Vaccination: Overcoming Parental and Physician Impediments." The CDC also advises physicians to recommend HPV vaccine "the same way, the same day as other vaccines." Identifying office workflow barriers, implementing previsit planning, and permitting walk-in vaccinations can help increase vaccine uptake as well. There's an AFP by Topic on Immunizations (excluding Influenza) with several other resources on discussing vaccine hesitancy and increasing vaccination rates if you'd like to read more.

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