Sexual Practices, Sexually Transmitted Diseases, and the Incidence of Anal Cancer

Abstract

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.

Human papillomavirus, smoking, and sexual practices in the etiology of anal cancer

“…In contrast to our previous study, 3 women who reported experience with anal intercourse were at increased risk for the development of both SCC and cloacogenic anal cancer (overall adjusted OR, 2.2; 95% CI, 1.4 -3.3). The prevalence of this exposure (32.1% of cases and 21.4% of controls) has increased compared with our previous results (16.9% of cases and 10.8% of controls).…”

“…Consistent with our previous report based on earlier years of diagnosis 3 and on results from other population-based studies [12][13][14] and nonpopulation-based studies, 15-17 men who were not exclusively heterosexual were at increased risk of anal cancer. In this study, nearly half of the men with anal cancer (47.1%) were not exclusively heterosexual, compared with 6.0% of male controls (OR, 17.3; 95% CI, 8.2-36.1).…”

“…The prevalence of this exposure (32.1% of cases and 21.4% of controls) has increased compared with our previous results (16.9% of cases and 10.8% of controls). 3 The latter levels are similar to the reported prevalence of anal intercourse among women in two other population-based studies conducted by Holly et al 12 and Frisch et al 13 The years of diagnosis in our previous study (1978 -1985) and those in the study by Holly et al (1979Holly et al ( -1986 were similar, whereas Frisch et al used patients who were diagnosed between 1991 and 1994.…”

“…Similar comments may apply to increased reporting of the lifetime num-ber of sexual partners and a history of genital warts over that reported in prior studies. [3][4][5]12 Status as a current smoker at the time of study enrollment has been a consistent risk factor in most studies of anal cancer 3,5,12,18 and in the larger population-based studies of other HPV-related SCC anogenital malignancies. 6,10,19 -24 In this study, current smoker status was related to the risk of anal cancer in both men and women.…”

High Prevalence of Smoking Among Urban-Dwelling Canadian Men Who Have Sex with Men

“…Moreover, reductions in smoking among MSM would mitigate risks for health problems that affect them disproportionately; for example, smoking appears to be a potent yet modifiable cofactor in the development of anal cancer. [14][15][16][17][18] Targeting smoking prevention and cessation initiatives among MSM is difficult since only a handful of studies have investigated correlates of smoking among sexual minorities. 3,4,6,11,13 We undertook the present study to determine the prevalence and correlates of smoking in a community-recruited cohort of urban-dwelling Canadian MSM.…”