title: Colorectal cancers of rare histologic types compared with adenocarcinomas.
abstract: OBJECTIVE
  To examine clinical characteristics of colorectal cancers of rare histologic types compared with adenocarcinomas.
  
  
  METHODS
  Review of a population-based registry with complete ascertainment.
  
  
  RESULTS
  There were 7,422 colorectal cancers, 4,900 (66 percent) colonic and 2,522 (34 percent) rectal. Two hundred fifty-five cancers (3 percent) were of nonadenocarcinoma varieties including 75 (33 percent) squamous, 74 (33 percent) malignant carcinoids, 37 (16 percent) transitional cell-like, 25 (11 percent) lymphomas, 9 (4 percent) sarcomas, and 2 (0.9 percent) melanomas. Sixty (1.2 percent) of the colon cancers occurred in the appendix, and proportionately more carcinoids accounted for these tumors. Compared with adenocarcinomas, colonic and rectal carcinoids and colonic lymphomas accounted for a larger proportion of cancers in the younger age groups. The elderly had proportionately fewer colonic carcinoids. Colonic carcinoids, rectal squamous-cell cancers, and rectal transitional cell-like cancers were more common in women. Colonic lymphomas had a worse prognosis than adenocarcinomas. Survival was better with colonic and rectal carcinoids and rectal transitional cell-like cancers than with adenocarcinomas.
  
  
  CONCLUSIONS
  Colorectal cancers of histologic varieties other than adenocarcinoma have distinctive epidemiologic and clinical traits.
authors.affiliation: Division of Gastroenterology, University of Utah Health Sciences Center, Salt Lake City.
authors.forename: J A
authors.initials: JA
authors.lastname: DiSario
authors.forename: R W
authors.initials: RW
authors.lastname: Burt
authors.forename: M L
authors.initials: ML
authors.lastname: Kendrick
authors.forename: W P
authors.initials: WP
authors.lastname: McWhorter
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology; D000328:Adult; D017677:Age Distribution; D000368:Aged; D002276:Carcinoid Tumor / Q000453:epidemiology; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology; D002295:Carcinoma, Transitional Cell / Q000453:epidemiology; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000453:epidemiology; D008297:Male; D008545:Melanoma / Q000453:epidemiology; D008875:Middle Aged; D012189:Retrospective Studies; D012509:Sarcoma / Q000453:epidemiology; D017678:Sex Distribution; D015996:Survival Rate