Black women may benefit less from current HPV vaccines: study

By Megan Brooks

NEW YORK (Reuters Health) - African American women may be less likely to benefit from currently available human papillomavirus (HPV) vaccines to prevent cervical cancer.

In a study, researchers detected HPV subtypes 16 and 18, the two main subtypes prevented by current HPV vaccines, far less often in African American women than in white women with precancerous cervical lesions.

The findings were presented today during a media briefing at the American Association for Cancer Research (AACR) 12th annual International Conference on Frontiers in Cancer Prevention Research in National Harbor, Maryland.

"The approved cervical cancer vaccines are effective but they may not be effective for everyone, particularly African American women," said conference chair and briefing moderator Dr. Paul Limburg from the Mayo Clinic.

Dr. Cathrine Hoyo, of Duke University School of Medicine in Durham, North Carolina, reported the study findings at the briefing. She said there is "enormous disparity between blacks and whites with respect to both incidence and mortality from cervical cancer."

It was thought that increasing screening would "solve this problem," she explained, but that hasn't panned out. While African Americans are screened at "much higher" rates than whites or Hispanics, they continue to have a higher incidence and mortality from cervical cancer, Dr. Hoyo said.

Differential distributions of oncogenic HPV genotypes among black and white women may explain this.

The research team evaluated HPV genotype distribution and cervical intraepithelial neoplasia (CIN) in 280 African American women and 292 non-Hispanic white women who had colposcopy following an abnormal Pap test.

Among all 572 women, 245 (43%) had no precancerous cervical abnormalities, 239 (42%) had early precancerous cervical abnormalities (CIN1), and 88 (15%) had advanced precancerous cervical abnormalities (CIN2 and CIN3).

White women and African American women were often infected with different HPV subtypes, the researchers found.

The most frequent HPV subtypes detected among white women with CIN1 were 16, 18, 56, 39 and 66, while HPV subtypes 33, 35, 58 and 68 were most commonly detected in their African American counterparts.

Among women with CIN2 or CIN3, HPV 16, 18, 33, 39 and 59 were the most common genotypes detected in white women, whereas HPV 31, 35, 45, 56, 58, 66 and 68 were the most prevalent in African American women.

A new HPV vaccine now in phase III trials targets nine HPV subtypes (6, 11, 16, 18, 31, 33, 45, 52 and 58).

"The most disconcerting part of this new vaccine is it doesn't include HPV 35, 66 and 68, three of the strains of HPV of which African American women are getting the most," Dr. Hoyo said in a conference statement. "We may want to rethink how we develop these vaccines, given that African Americans tend to be underrepresented in clinical trials," she added.

"This is early research and data always have to be replicated in other studies," Dr. Limburg cautioned.

"As we get vaccines out into the community and in clinical practice, I think we always need to be mindful of monitoring and determining where are those population groups that may be benefiting more or benefiting less," he added.

"I think we need to do a better job of recognizing that a cancer vaccine doesn't work for everybody and we need to figure out why that may be the case and then do our best to come up with additional vaccines or additional approaches," Dr. Limburg said.

The research was supported by the National Cancer Institute.