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HPV vaccine success may reduce need for screening

Studies show vaccines protected against several strains of HPV

Adrian O'Dowd

Wednesday, 09 November 2011

The success of using the human papillomavirus (HPV) vaccine Cervarix in reducing incidence of cervical cancer in adolescent girls may reduce the need for future screening for the disease, according to two studies published today in The Lancet Oncology.

American and Finnish researchers studied the effectiveness of Cervarix, produced by GlaxoSmithKline, and found it provided excellent protection against the more serious immediate precursor to invasive cervical cancer, particularly when given to young adolescent girls before they became sexually active.

The studies also found that the vaccine partially protected against four other cancer-causing HPV types not targeted by the formulation, that together with HPV16/18, cause about 85% of cervical cancer globally.

In the first study, almost 20,000 healthy women aged 15–25 years from 14 countries in Asia-Pacific, Europe, Latin America, and North America took part.

Women were randomly assigned to receive the bivalent HPV vaccine or a control (hepatitis A) vaccine, given in three doses at enrolment, one month, and six months.

After four years of follow-up, the researchers found the bivalent HPV vaccine resulted in high rates of protection against high-grade cervical precancers (CIN3+), early development of adenocarcinoma (AIS), and 12 other cancer-causing HPV types not targeted by the vaccine.

The authors concluded: “Appropriate effectiveness and implementation studies assessing the combination of vaccination and new screening strategies are warranted.”

One of the lead authors Professor Matti Lehtinen from University of Tampere in Finland, said: “Provided that organised vaccination programmes achieve high coverage in early adolescents before sexual debut, HPV vaccination has the potential to substantially reduce the incidence of cervical cancer, probably allowing modification of screening programmes… when conducted alongside vaccination strategies.”

In the second study, the vaccine showed increased cross-protection against other cancer-causing HPV types 31, 33, 45, and 51 in different cohorts representing diverse groups of women.

Lead author of this study, Professor Cosette Wheeler from the University of New Mexico Health Sciences Center, Department of Pathology, USA, said: “There is a particularly high risk of HPV-33 infections progressing to cervical lesions, and HPV-45 is over-represented in adenocarcinoma…Our results show that cross-protective efficacy might provide substantial additional protection against cervical cancer beyond protection conferred against HPV-16/18.”

In an accompanying comment, Mark Schiffman and Sholom Wacholder from the National Cancer Institute, Rockville, USA, said: “We believe that increasing coverage, particularly of sexually-naïve adolescent females, is now the most important public-health issue in HPV vaccination efforts.

“We are particularly concerned about low vaccination rates in areas where cervical cancer incidence and mortality are high because of inadequate alternative prevention through effective cervical screening, and where nine of 10 cervical cancers deaths occur…The current vaccines are too expensive and difficult to deliver for many low-resource regions.”

doi:10.1016/S1470-2045(11)70286-8
doi:10.1016/S1470-2045(11)70287-X

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