Nov. 5, 2002 -- Genital herpes increases the risk of cervical cancer -- which kills thousands of women every year -- by acting as an "accomplice" to another common virus that commonly causes this cancer.
Herpes simplex virus-2, the cause of genital herpes, was detected in nearly half of women with invasive cervical cancer -- nearly twice as often as in women without signs of cancer, researches report in a study published in the Nov. 6 issue of the Journal of the National Cancer Institute.
But this doesn't mean that all women with herpes simplex-2 (HSV-2) are at increased risk. In fact, those diagnosed with HSV-2 face no additional risk if they are not also infected with human papillomavirus (HPV).
"The message of this study is to reinforce the importance of getting regular Pap smear screenings at good laboratories, which detect the presence of papillomavirus," says Mark Schiffman, MD, of the National Cancer Institute, who was not involved in the study.
"If you get regular Pap screenings and they produce normal results, then relax," he tells WebMD. "Even if you have been diagnosed with herpes 2, it's a minor player in the risk of cervical cancer and is only active when in conjunction with papillomavirus."
There are nearly 100 different types of HPV, and together they infect about 24 million Americans. About one-third are transmitted through sexual contact without a condom or diaphragm and most are harmless, while others cause genital warts.
However, "there are 14 high-risk HPV types that have been clearly shown to cause invasive cervical cancer," lead researcher Jennifer Smith, PhD, tells WebMD. These strains cause at least 90% of all cervical cancers, as well as other genital cancers.
In her study, researchers at the International Agency for Research on Cancer in France found that women infected with both HPV and HSV-2 were two to three times more likely to get cervical cancer. They studied nearly 2,400 women living in seven countries in Asia, Europe, and Latin America. Women of Asian descent have the highest frequency of cervical cancer.
"This study was done in countries that typically have very little in the way of formal Pap screening programs and management of minor abnormalities," says Schiffman. "It's an attempt by scientists to further determine how HPV uncommonly progresses to cervical cancer and to further clarify what is already one of the best understood cancers."
Although among the more common cancers affecting women, when detected early -- via a Pap smear -- cervical cancer has a nearly 100% cure rate. Since 1955, its death rate has decreased by 74%, primarily because of increased use of Pap screenings. Most women have been advised to have at least one screening a year; those who have gotten "abnormal" results may require two or three per year. The American Cancer Society is expected to announce new recommendations by month's end.
The herpes-2 virus is among several factors that work in conjunction with HPV in boosting cervical cancer risk. Previous studies indicate that using oral contraceptives for more than five years doubles the risk in those with HPV, while having more than seven births boosts risk four times. Other suspected co-factors include being sexually active in adolescence, smoking, and giving birth before age 20.
There is no cure for HSV-2, which also is spread through unprotected sexual contact and now infects an estimated one in five Americans older than age 12, according to the CDC. When active, it can trigger painful and highly infectious sores on the genitalia.
Another type of herpes simplex virus that causes cold sores on the mouth - HSV-1 - has not been implicated in the HPV-cervical cancer link, says Smith.