title: Comparative Survival of Patients With Anal Adenocarcinoma, Squamous Cell Carcinoma of the Anus, and Rectal Adenocarcinoma.
abstract: BACKGROUND
  Anal adenocarcinoma (AA) represents 5% to 10% of anal cancer. Little is known about its natural history and prognosis. Using population-based data, we defined the outcomes of AA relative to other anorectal malignancies.
  
  
  METHODS
  We analyzed the Surveillance, Epidemiology, and End Results 18 database to identify patients ≥ 18 years old with AA, squamous cell carcinoma of the anus (SCCA), and rectal adenocarcinoma (RA) diagnosed between 1990 and 2011. Median overall survival (OS), 1-year, 3-year, 5-year, and 10-year OS were computed using actuarial methods. The log rank test was used to estimate the difference between Kaplan-Meier survival curves. A Cox proportional hazard regression model was used to adjust the effects of other covariates on survival, including age, year diagnosed, sex, stage, surgery, and radiation.
  
  
  RESULTS
  Of 57,369 cases, 0.8% (n = 462) were patients with AA, 87.8% (n = 50,382) were patients with RA, and 11.4% (n = 6525) were patients with SCCA. The median age for AA was 69 years (range, 20-96 years), 66 years (range, 18-103 years) for RA, and 66 years (range, 14-104 years) for SCCA. The median OS was significantly lower for AA (33 months), compared with SCCA (118 months) and RA (68 months) (P < .01). In multivariate analysis, AA had a worse prognosis compared with SCCA (hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.59-0.75; P < .01) and RA (HR, 0.68; 95% CI, 0.61-0.77; P < .01), after adjusting for age, sex, race, stage, grade, radiation, and surgery. There was a strong trend for improved survival among patients who received radical surgery (HR, 0.71; 95% CI, 0.51-1.00; P = .05).
  
  
  CONCLUSIONS
  AA confers a significantly worse prognosis than SCCA and RA.
authors.affiliation: College of Medicine, The University of Tennessee Health Science Center, Memphis, TN. Electronic address: rfrankln@gmail.com.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Franklin
authors.affiliation: College of Medicine, The University of Tennessee Health Science Center, Memphis, TN.
authors.forename: Smith
authors.initials: S
authors.lastname: Giri
authors.affiliation: College of Medicine, The University of Tennessee Health Science Center, Memphis, TN.
authors.forename: Poojitha
authors.initials: P
authors.lastname: Valasareddy
authors.affiliation: Department of Internal Medicine, The University of Tennessee Health Science Center, Memphis, TN; Department of Hematology/Oncology, The West Cancer Center, The University of Tennessee Health Science Center, Memphis, TN.
authors.forename: Lindsey T
authors.initials: LT
authors.lastname: Lands
authors.affiliation: Department of Hematology/Oncology, The West Cancer Center, The University of Tennessee Health Science Center, Memphis, TN.
authors.forename: Mike G
authors.initials: MG
authors.lastname: Martin
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents; D001005:Anus Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D002294:Carcinoma, Squamous Cell / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D059248:Chemoradiotherapy; D003131:Combined Modality Therapy; D013505:Digestive System Surgical Procedures; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models; D011878:Radiotherapy; D012004:Rectal Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D018426:SEER Program; D012737:Sex Factors; D015996:Survival Rate; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents
keywords: Anal cancer; Population-based; Radiochemotherapy; Rectal cancer; Surgery