* Human papillomavirus: Examination of squamous cell carcinoma tumor tissues from patients in Denmark and Sweden showed a high proportion of<unk> s to be positive for the types of HPV that are also associated with high risk of cervical<unk> . In another study done, high-risk types of HPV, notably HPV-16, were detected in 84 percent of<unk>  specimens examined. Based on the study in Denmark and Sweden, Parkin estimated that 90% of<unk> s are attributable to HPV. * Sexual activity: Due to increased risk of exposure to HPV, having multiple sex partners and receptive anal intercourse greatly increases the likelihood of developing<unk> , for men and women. * Smoking: Current smokers are several times more likely to develop<unk>  compared with nonsmokers. Epidemiologist Janet Daling, Ph.D., a member of Fred Hutchinson's Public Health Sciences Division, and her team found that smoking appears to play a significant role in<unk>  development that is independent of other behavioral risk factors, such as sexual activity. More than half of the<unk>  patients studied were current smokers at the time of diagnosis, as compared to a smoking rate of about 23 percent among the controls. "Current smoking is a very important promoter of the disease," said Daling. "There's a fourfold increase in risk if you're a current smoker, regardless of whether you're male or female." They explained that the mechanism behind smoking and<unk>  development is unknown, but researchers speculate that smoking interferes with a process called apoptosis, or programmed cell death, which helps rid the body of abnormal cells that could turn<unk> ous. Another possibility is that smoking suppresses the immune system, which can decrease the body's ability to clear persistent infection or abnormal cells. * Immunosuppression, which is often associated with HIV infection. * Benign anal lesions. * A history of cervical, vaginal or vulval<unk> s * Cloacogenic. Cloacogenic carcinoma is a rare tumor of the anorectal region originating from a persistent remnant of the cloacal membrane of the embryo. The tumor accounts for 2–3% of anorectal carcinomas and occurs more than twice as often in women.
Anal cancer
Genital wart
Anal fissure
Hemorrhoid
Anal fistula
Genital ulcer
Anorectal varices
Perianal cellulitis