ATLANTA — The recently approved quadrivalent human papillomavirus vaccine shown to be effective for preventing most HPV-related cervical cancers may also prevent most vulvar and vaginal cancers, Dr. Jorma Paavonen reported at the annual meeting of the American Society of Clinical Oncology.
The vaccine (Gardisil, Merck & Co.) received approval from the Food and Drug Administration this month.
Gardisil targets HPV 6 and 11, which are associated with anogenital warts, and HPV 16 and 18, which cause most cervical cancers. HPV 16 and 18 are also the most common causes of vulvar and vaginal cancers, said Dr. Paavonen, professor and chief physician in obstetrics and gynecology at the University of Helsinki, Finland.
The FUTURE II study was a combined analysis of data from three randomized, placebo-controlled trials that studied the impact of the vaccine on rates of HPV 16- and 18-related vulvar and vaginal intraepithelial neoplasia grade 2/3.
FUTURE II showed that the vaccine was 100% effective up to 2 years of follow-up for preventing these precancerous lesions, said Dr. Paavonen, who has served as a consultant to Merck & Co. and received research funding from the company.
A total of 18,150 women aged 16–26 were randomized in these trials to receive either the vaccine or placebo. Vaccination occurred at day 1 and at 2 and 6 months. Genital tract specimens were obtained at day 1 and then at 6- to 12-month intervals for up to 48 months, with colposcopy performed as needed following algorithm-based referrals.
On per-protocol analysis, there were 10 cases of vulvar intraepithelial neoplasia (VIN) 2/3 or vaginal intraepithelial neoplasia (VaIN) 2/3 in the placebo group, and none in the vaccine group, at an average of 18 months of follow-up. On modified intention-to-treat analysis, there were 24 histologically confirmed cases of VIN 2/3 or VaIN 2/3 in the placebo group, at an average of 2 years of follow-up.
“The burden of HPV disease is not restricted to the cervix. HPV is present in nearly 80% of the 6,000 cases of vaginal and vulvar cancers that are diagnosed in the United States each year,” Dr. Paavonen said. The vaccine is expected, based on these findings, to greatly reduce the risk of vulvar and vaginal cancers, he noted.