title: Second Primary Malignancy in Anal Carcinoma--A US Population-based Study.
abstract: OBJECTIVE
  To our knowledge, there are no data on second primary malignancies in anal cancer. This study was conducted to evaluate the risk of second primary malignancies in patients with anal carcinoma.
  
  
  METHODS
  We selected adult patients diagnosed with anal cancer from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) 13 database. We calculated the risk of second primary malignancies in these patients using multiple primary standardized incidence ratio (MP-SIR) session of SEER statistical software.
  
  
  RESULTS
  Among 7,661 patients, 675 (9.07%) developed 747 second primary malignancies, with an observed/expected ratio of 1.41 (95% confidence interval=1.32-1.52, p<0.001), and an absolute excess risk of ~55 per 10,000 population. Significant excess risks were observed for tumors of the oral cavity and pharynx, rectum and anal canal, larynx, lung and bronchus, ovary, vagina, and vulva, and Kaposi's sarcoma and hematological malignancies. The risk of specific second primary malignancies was related to the age of patients, exposure to radiotherapy and latency period.
  
  
  CONCLUSIONS
  The risk of second primary malignancies in adult patients with anal cancer is significantly increased compared to the general population.
authors.affiliation: Cancer Center and Blood Institute, St. Joseph Regional Medical Center, Lewiston, ID, U.S.A. binay.shah@gmail.com.
authors.forename: Binay Kumar
authors.initials: BK
authors.lastname: Shah
authors.affiliation: Cancer Center and Blood Institute, St. Joseph Regional Medical Center, Lewiston, ID, U.S.A.
authors.forename: Nibash
authors.initials: N
authors.lastname: Budhathoki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001005:Anus Neoplasms / Q000150:complications* / Q000473:pathology; D002277:Carcinoma / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000453:epidemiology* / Q000209:etiology*; D012306:Risk; D012307:Risk Factors
keywords: Anal cancer; SEER; latency; second primary malignancy