HealthDay News — Black women are more likely to have strains of human papillomavirus that do not match the genotypes included in available vaccines, suggesting the potential for reduced vaccine effectiveness, according to study findings presented at the 12th Annual American Association for Cancer Research’s International Conference on Frontiers in Cancer Prevention Research.
Four viral strains not included in the HPV vaccines currently on the market — genotypes 31, 45, 51 and 66 — were the most common high-risk HPV subtypes identified among black women with abnormal Pap tests, Cathrine Hoyo , PhD, MPH, of Duke University School of Medicine in Durham, N.C., and colleagues found.
“Although our findings need to be replicated in larger cohorts of women, they suggest that the currently available HPV vaccines, which target HPV subtypes 16 and 18 in order to prevent cervical cancer and precancerous cervical abnormalities, will be less beneficial for African-American women than non-Hispanic white women,” Hoyo said in a press release.
She and colleagues are currently enrolling women undergoing a colposcopy after abnormal Pap tests to determine whether certain markers distinguish early cervical intraepithelial neoplasia (CIN1) — a form of precancerous cervical abnormality — from more advanced CIN2 and CIN3.
As part of the Cervical Intraepithelial Neoplasia Cohort Study (CINCS), the researchers evaluated HPV subtypes from a multiethnic cohort of 572 participants, including 280 black and 292 non-Hispanic white women.
Overall, 72% of the women were HPV-positive and 37% had no cervical intraepithelial neoplasia (CIN). Among women with any CIN, 47% had CIN1, 10% had CIN2 and 6% had CIN3.
Among CIN1 cases, the most frequent high-risk HPV genotypes were 16, 18, 31, 45, 52, 56, 59 and 66 in white women (N=127), and genotypes 33, 35, 58 and 68 in black women (N=112).
For CIN2 and CIN3, the most common high-risk HPV genotypes among white women (N=47) were 16, 18, 33, 35, 39 and 59, compared with genotypes 31, 45, 51 and 66 in black women (N=41).
“We found a much lower prevalence of HPV 16 and 18 in advanced CIN [CIN2 and 3] from African-American women. Rather, their CIN2 and 3 frequently harbored HPV 31, 35, 45, 56, 58, 66 and 68, all of which are linked to cervical cancer,” Hoyo said.
An HPV vaccine with protection against nine HPV genotypes currently in phase III clinical trials, may be more beneficial to black women, as it covers three of the most common cervical cancer-associated HPV subtypes in those with CIN2 and CIN3, including genotypes 31, 45 and 58. The novel vaccine also protects against HPV genotypes 6, 11, 16, 18, 33 and 52.
“We need more African-American women to enroll in trials like this to see how beneficial this new vaccine will be for them,” Hoyo said.