Published in UAB Insight, Summer 2008
Fewer Abnormal Pap Smears Reduce Follow-up Procedures, Patient Anxiety
Several years may be needed to determine whether the human papilloma virus (HPV) vaccine Gardasil prevents cervical cancer, but a recent study clearly shows the quadrivalent vaccine significantly reduces abnormal Pap test results and the need for cervical biopsies and colposcopies, gynecologic oncology researcher Warner K. Huh, MD, says. Gardasil protects against HPV strains that together account for 70% of cases of cervical cancers and 90% of genital wart cases.
Huh is an investigator for the UAB site of the Gardasil clinical trial that led to Food and Drug Administration (FDA) approval of the agent in 2006 and is involved in other HPV vaccine studies.
Cervical cancer screening is extremely effective but carries an expensive price tag in follow-up procedures and treatments, he says. His study results suggest that the vaccine will spare thousands of women a diagnosis of cell abnormality or malignant change that may lead to more tests and possibly surgery, Huh says. He presented his evaluation of three separate studies involving more than 18,000 women on three continents to the Society of Gynecologic Oncologists earlier this year.
During a 4-year period, women vaccinated with the quadrivalent vaccine experienced 43% fewer severely abnormal Pap smears and 42% fewer invasive cervical procedures to treat precancerous abnormalities compared with women receiving a placebo. "We did not expect such a significant reduction so quickly," Huh says.
One in three women in the US will have an abnormal Pap smear in their lifetime. The study only involved women aged 16 to 26 years who had a low likelihood of exposure to HPV before enrollment and thus were likely to benefit more from the vaccine. In addition, the actual number of women who developed severely abnormal cervical lesions was small.
"Despite these limitations the findings are impressive and should help relieve the anxiety of women faced with an abnormal screening result," he says. "It gives physicians information on further benefits of the vaccine, which may be helpful when encouraging patients to complete the three-dose regimen."
Huh notes that in addition to Gardasil, a bivalent HPV vaccine is approved for use in the European Union and is currently under FDA review. Both vaccines confer protection against HPV 16 and 18 strains that are believed to cause 70% of cervical cancer. Gardasil also protects against HPV 6 and 11 strains, which cause almost all cases of genital warts. The FDA has granted a priority review for Merck's application to expand marketing of Gardasil to women aged 27 to 45 years.
"Other studies of Gardasil also show some degree of cross-protection against other strains of HPV that are thought to cause some of the remaining 30% of cervical cancer as well as vulvar and vaginal cancers," Huh says.
"These recent vaccine findings are exciting. We have quickly gone from having a continuing major public health problem to the high likelihood that we can prevent most of these diseases," he says. "Even though the Holy Grail of reduction of cervical cancer may be 20 years away, we now can immediately reduce the number of abnormal Pap tests."
After reviewing almost 10,000 reports of adverse events after Gardasil injection, the FDA and Centers for Disease Control and Prevention issued a statement on July 22 saying that, "Gardasil continues to be safe and effective, and its benefits continue to outweigh its risks."
Huh maintains a consulting and speaker's bureau relationship with Merck & Co, Inc.
FOR MORE INFORMATION:
Dr. Warner Huh
1.800.UAB.MIST
mist@uabmc.edu