title: Impact of the HIV epidemic on the incidence rates of anal cancer in the United States.
abstract: BACKGROUND
  The risk of anal cancer is substantially increased in HIV-infected individuals. Thus, the HIV epidemic may have influenced the increasing anal cancer trends in the United States. We estimated the impact of the HIV epidemic on trends in anal cancer incidence in the United States during 1980-2005.
  
  
  METHODS
  Data on anal cancer cases with and without AIDS were obtained from the HIV/AIDS Cancer Match Study. The number of HIV-infected anal cancer cases without AIDS was estimated from the number of anal cancers occurring before diagnosis of AIDS. The proportion of anal cancer cases with HIV infection in the general population was calculated. We estimated temporal trends in the incidence rates of anal cancer in the general population overall and after exclusion of HIV-infected cancer cases by calculating annual percent changes and 95% confidence intervals (CIs) using a Joinpoint log-linear model. All incidence rates were standardized to the 2000 US population by age, sex, and race.
  
  
  RESULTS
  During 1980-2005, of the 20 533 estimated anal cancer cases, 1665 (8.1%) were HIV-infected. During 2001-2005, the proportion of anal cancer cases with HIV infection was the highest-1.2% (95% CI = 0.93 to 1.4%) among females and 28.4% (95% CI = 26.6 to 29.4%) among males. During 1980-2005, HIV infection did not have an impact on the trends in anal cancer among females (incidence rates increased by 3.3% [95% CI = 3.0 to 3.7%] annually overall, and by 3.3% [95% CI = 2.9 to 3.6%] annually without HIV-infected anal cancer cases) but had a strong impact on the trends in anal cancer among males (incidence rates increased by 3.4% [95% CI = 2.9 to 3.9%] annually overall, and by 1.7% [95% CI = 1.2 to 2.3%] annually without HIV infection).
  
  
  CONCLUSIONS
  During 1980-2005, the increasing anal cancer incidence rates in the United States were strongly influenced by the HIV epidemic in males but were independent of HIV infection in females.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD 20892, USA. shielsms@mail.nih.gov
authors.forename: Meredith S
authors.initials: MS
authors.lastname: Shiels
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Pfeiffer
authors.forename: Anil K
authors.initials: AK
authors.lastname: Chaturvedi
authors.forename: Aimee R
authors.initials: AR
authors.lastname: Kreimer
authors.forename: Eric A
authors.initials: EA
authors.lastname: Engels
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000453:epidemiology; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001005:Anus Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000821:virology*; D058872:Epidemics; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D017678:Sex Distribution; D012725:Sexual Behavior; D013997:Time Factors; D014481:United States / Q000453:epidemiology