New indication OK'd for HPV vaccine
Add new information in your counseling dialogue regarding the human papillomavirus (HPV) vaccine Gardasil. The Food and Drug Administration (FDA) has approved the Merck & Co. quadrivalent vaccine for prevention of anal cancer and associated precancerous lesions related to HPV types 6, 11, 16, and 18 in people ages 9-26.
Gardasil already has approval for the same age population for the prevention of cervical, vulvar, and vaginal cancer and the associated precancerous lesions caused by HPV types 6, 11, 16, and 18 in females. It also is approved for the prevention of genital warts caused by types 6 and 11 in males and females.
Treatment for anal cancer is challenging, stated Karen Midthun, MD, director of the FDA's Center for Biologics Evaluation and Research, in a statement released with the December 2010 indication approval. The use of Gardasil as a method of prevention is important as it might result in fewer diagnoses and the subsequent surgery, radiation, or chemotherapy that individuals need to endure, she said.
Check study results
Approval for the new indication was based on a single randomized, controlled trial of 4,065 patients, including 602 men who have sex with men (MSM). Among the MSM population, the point estimate of efficacy for Gardasil was 78% (95% confidence interval [CI], 40-93) for the primary composite endpoint of prevention of any grade anal intraepithelial neoplasia and anal cancer. Efficacy was 75% (95% CI, 9-93) for grade 2 or higher anal intraepithelial neoplasia. No cases of invasive anal cancer were noted in the study.
The study yielded overall efficacy of 50% (95% CI, 26-27) for any grade anal intraepithelial neoplasia and anal cancer. For grade 2 or higher anal intraepithelial neoplasia, efficacy was 54% (95% CI, 18-75).1
Because anal cancer is the same disease in males and females, the effectiveness data was used to support the indication in females as well.
While anal cancer is uncommon in the general population, the incidence is increasing, according to the FDA. HPV is associated with about 90% of anal cancer. The American Cancer Society estimates that about 5,300 people are diagnosed with anal cancer each year in the United States.2 It is estimated that about 1,600 new cases of HPV-associated anal cancers are diagnosed in women, and about 900 are diagnosed in men each year in the United States.3 More white women are diagnosed with anal cancer than women of other races; more black men are diagnosed with anal cancer than men of other races.
There is no standardized screening recommended for the general population for anal cancer. A digital rectal exam will find some cases of anal carcinoma early. This test is sometimes used to look for prostate cancer in men and is a routine part of a woman's pelvic exam. The odds that anal cancer can be found early depend on the location and type of the cancer, according to the American Cancer Society.
For people at high risk for anal intraepithelial neoplasia (AIN), such as men who have sex with men, women who have had cervical cancer or vulvar cancer, those who are HIV-positive, and all transplant recipients, some experts recommend screening with anal cytology testing. Known as an anal Pap test or anal Pap smear, the test is performed by swabbing the anal lining, with swab contents examined under a microscope.
Science has not yet determined how often an anal Pap test should be done or if it reduces the risk of anal cancer, according to the American Cancer Society. Some experts recommend the test be repeated on an annual basis in HIV-positive men who have sex with men and every two to three years if the men are HIV-negative.4
References
- FDA approves HPV vaccine for anal cancer. Infectious Disease News. Jan. 1, 2011. Accessed at http://www.infectiousdiseasenews.com/article/78864.aspx.
- American Cancer Society. How many people get anal cancer? Last revised Dec. 23, 2010. Accessed at http://www.cancer.org/Cancer/AnalCancer/OverviewGuide/anal-cancer-overview-key-statistics.
- Joseph DA, Miller JW, Wu X, et al. Understanding the burden of human papillomavirus-associated anal cancers in the US. Cancer 2008;113(S10):2892–2900.
- American Cancer Society. Can anal cancer be found early? Accessed at http://www.cancer.org/Cancer/AnalCancer/DetailedGuide/anal-cancer-detection.
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