HPV appears to be the key risk factor for cervical adenocarcinoma. HPV testing in primary screening using current mixtures of HPV types and HPV vaccination against main HPV types should reduce the incidence of this cancer worldwide.

Seropositivity for HSV-2 is associated with viral shedding in the genital tract, even in subjects with no reported history of genital herpes.

Efficient and sustained protection from sexual acquisition of HSV-2 infection will require more than high titers of specific neutralizing antibodies. Protection against sexually transmitted viruses involving exposure over a prolonged period will require a higher degree of vaccine efficacy than that achieved in this study.

To elucidate the risk factors for anal cancer, we interviewed and obtained blood specimens from 148 persons with anal cancer and from 166 controls with colon cancer in whom these diseases were diagnosed during 1978-1985. We found that in men, a history of receptive anal intercourse (related to homosexual behavior) was strongly associated with the occurrence of anal cancer (relative risk, 33.1; 95 percent confidence interval, 4.0 to 272.1). Anal intercourse was only weakly associated with the risk of anal cancer in women (relative risk, 1.8; 95 percent confidence interval, 0.7 to 4.2). Among the subjects with squamous-cell anal cancer, 47.1 percent of homosexual men, 28.6 percent of heterosexual men, and 28.3 percent of women gave a history of genital warts, as compared with only 1 to 2 percent of controls and no patients with transitional-cell anal cancer. In patients without a history of warts, anal cancer was associated with a history of gonorrhea in heterosexual men (relative risk, 17.2; 95 percent confidence interval, 2.0 to 149.4) and with seropositivity for herpes simplex type 2 (relative risk, 4.1; 95 percent confidence interval, 1.9 to 8.8) and Chlamydia trachomatis (relative risk, 2.3; 95 percent confidence interval, 1.1 to 4.8) in women. Current cigarette smoking was a substantial risk factor in both women (relative risk, 7.7; 95 percent confidence interval, 3.5 to 17.2) and men (relative risk, 9.4; 95 percent confidence interval, 2.3 to 38.5). We conclude that homosexual behavior in men is a risk factor for anal cancer, and that squamous-cell anal cancer is also associated with a history of genital warts, an association suggesting that papillomavirus infection is a cause of anal cancer. Certain other genital infections and cigarette smoking are also associated with anal cancer.

Among women with a history of genital herpes infection, subclinical shedding of HSV is common and accounts for nearly one third of the total days of reactivation of HSV infection in the genital tract. Women with frequent symptomatic recurrences also have frequent subclinical shedding and may be at high risk for transmitting HSV.

Nearly 40 percent of newly acquired HSV-2 infections and nearly two thirds of new HSV-1 infections are symptomatic. Among sexually active adults, new genital HSV-1 infections are as common as new oropharyngeal HSV-1 infections.

A larger study would allow examination of interrelationships of circumcision, infection with HPV, and smoking as risk factors.

Almost all persons with initially symptomatic HSV-2 infection have symptomatic recurrences. More than 35% of such patients have frequent recurrences. Recurrence rates are especially high in persons with an extended first episode of infection, regardless of whether they receive antiviral chemotherapy with acyclovir. Men with genital HSV-2 infection have about 20% more recurrences than do women, a factor that may contribute to the higher rate of HSV-2 transmission from men to women than from women to men and to the continuing epidemic of genital herpes in the United States.