At Significantly Higher Risk 
• This cancer is more common in women over 40.
• Primary association with a history of chronic anal irritation—genital warts (condyloma), abscesses, fistulas,
  fissures , scars and infections such as chlamydia, trichomonas, genital herpes, gonorrhea and radiation
  dermatitis.
• Associated with venereal warts and the presence of the papilloma virus .
• Anal margin cancer (cancer encircling the anus) is more common in men.
• Increased incidence in cigarette smokers. 
• Increased risk in homosexuals, probably related to anal intercourse and infections with a retrovirus such as
  HIV (human immunodeficiency virus) and HPV (human papilloma viruses).
• Persons with symptomatic HIV disease, lower CD4 (T4) blood counts.
• There is an increased incidence of anal cancer with cervical, vaginal and vulvar high-grade intraepithelial
  neoplasia (grade 3).
• Anal cancer may occur along with benign anal disease. It is more common in those with hemorrhoids, anal
  degenerative skin changes and white plaque (leukoplakia) on the mucous membranes.