title: Second primary cancer in patients with colorectal cancer after a curative resection.
abstract: BACKGROUND
  Colorectal cancer (CRC) patients have an increased risk of developing other malignancies. Understanding the characteristics of the second primary cancer is important to establish an effective surveillance program.
  
  
  METHODS
  This study investigated 301 CRC patients to assess the risk factors for postoperative primary cancers arising from organs distinct from the colorectal area (extracolorectal cancers). The observed/expected ratio (O/E ratio) was calculated using the Osaka Cancer Registry, to determine the rate of increase in extracolorectal cancers.
  
  
  RESULTS
  The frequency of postoperative extracolorectal cancers was 12.6%. A logistic regression analysis showed only age to be an independent risk factor for postoperative extracolorectal cancer development. The O/E ratio of overall postoperative extracolorectal cancer was significantly higher than one (O/E ratio 2.6, p < 0.01). In each organ, the frequency of lung and gastric cancers were significantly higher than one, with O/E ratios of 3.2 and 2.7 (p < 0.01 and p < 0.05, respectively).
  
  
  CONCLUSIONS
  The frequency of postoperative extracolorectal cancers in CRC patients was significantly higher than that in the normal population, especially for lung and gastric cancers. Clinicians should carefully follow patients for a possible recurrence of CRC and educate CRC patients with regard to the high risk of a second primary cancer.
authors.affiliation: Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan. noura-si @ mc.pref.osaka.jp
authors.forename: Shingo
authors.initials: S
authors.lastname: Noura
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ohue
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Seki
authors.forename: Koji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Masaaki
authors.initials: M
authors.lastname: Motoori
authors.forename: Kentaro
authors.initials: K
authors.lastname: Kishi
authors.forename: Isao
authors.initials: I
authors.lastname: Miyashiro
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ohigashi
authors.forename: Masahiko
authors.initials: M
authors.lastname: Yano
authors.forename: Osamu
authors.initials: O
authors.lastname: Ishikawa
authors.forename: Hideaki
authors.initials: H
authors.lastname: Tsukuma
authors.forename: Kohei
authors.initials: K
authors.lastname: Murata
authors.forename: Masao
authors.initials: M
authors.lastname: Kameyama
mesh_terms: D000230:Adenocarcinoma / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003082:Colectomy / Q000379:methods*; D015179:Colorectal Neoplasms / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016609:Neoplasms, Second Primary / Q000453:epidemiology* / Q000473:pathology; D012042:Registries; D012307:Risk Factors