TUESDAY, March 27 (HealthDay News) -- A new study finds that women diagnosed with pre-cancerous cervical conditions after they get the human papillomavirus (HPV) vaccine can still benefit from the shot because it cuts their risk of future HPV-related cervical disease.

"This study helps to clarify the effects of the HPV vaccine and further define its use," noted one expert, Dr. Elizabeth Poynor, a gynecologic oncologist and pelvic surgeon at Lenox Hill Hospital in New York City.

Poynor, who was not involved in the new research, said it "is the first to address the effect of the HPV vaccine in women who have undergone treatment for HPV-related disease."

The study was published online March 27 in the BMJ.

HPV remains the most common sexually transmitted infection in the United States and can cause health problems ranging from genital warts to cervical cancer, according to the U.S. Centers for Disease Control and Prevention. HPV infection is thought to be the leading cause of cervical cancer, and two HPV vaccines, Gardasil and Cervarix, have received U.S. Food and Drug Administration approval.

Previous research has shown that HPV vaccination does not prevent progression to cervical pre-cancers in women who have an HPV infection when they receive the vaccine.

However, this is the first study to examine if HPV vaccination can prevent future cervical disease in these women after they've been successfully treated for their current condition, the researchers pointed out in a journal news release.

The study involved an international team of researchers led by Dr. Elmar Joura of the Medical University of Vienna. The investigators analyzed data from 1,350 young women in 24 developed and developing countries who took part in two clinical trials in which they received either the HPV vaccine or an inactive placebo. The women were subsequently diagnosed with either a vulvar or vaginal disease (including genital warts) or had required cervical surgery.

Among women who required cervical surgery after taking part in the studies, the risk of getting a subsequent HPV-related disease was 6.6 cases per 100 women per year among those who received the HPV vaccine and 12.2 cases per 100 women per year among those who received the placebo. This translates into more than a 46 percent reduced risk for women who received the HPV vaccine, the authors noted.

The researchers also found that the risk of pre-cancerous changes of the cervix and other "high-grade" cervical disease was almost 65 percent lower in those who received the HPV vaccination than in those who received the placebo.

Among women who were diagnosed with and treated for vaginal or vulvar disease, the risk of any future HPV-related disease was about 35 percent lower among those who received the HPV vaccine than among those who received the placebo, the study authors reported.

Two other experts said the findings appear heartening.

"While questions remain on the design of the study, it offers another reassurance that the efficacy of the quadrivalent HPV vaccine as initial protection may extend to decreasing subsequent diseases after initial vaccination," said Dr. Linus Chuang, director of gynecologic oncology at Mount Sinai Medical Center in New York City.

And Dr. Stephanie Blank, director of the gynecologic oncology fellowship at NYU School of Medicine, agreed that the study "describes potential further benefits of the HPV vaccine. HPV causes cervical cancer but affects even more women by causing cervical dysplasia [abnormal cell growth]." She noted that "dysplasia, which itself is only dangerous due to its association with cancer, results in multiple procedures, extensive health care costs and patient angst."

More information

The U.S. Centers for Disease Control and Prevention has more about HPV vaccination.