title: Usefulness of analytical CEA doubling time and half-life time for overlooked synchronous metastases in colorectal carcinoma.
abstract: BACKGROUND
  Measurement of carcinoembryonic antigen (CEA) has been widely applied to detect recurrence, especially of colorectal carcinoma. The validity however, is still controversial. We investigated serial changes in CEA values to calculate whether the CEA doubling time and half-life time could predict metastatic progression or prognosis in colorectal carcinoma.
  
  
  METHODS
  Pre- and post-operative serial serum CEA contents were determined in 22 cases of colorectal cancer with or without metastasis. CEA values were determined by enzyme immunoassay (EIA). Patients were assigned depending upon survival time (within vs. more than 18 months after primary resection) for assessment of CEA doubling time. From the gradient of the semi-logarithmic CEA graph, the preoperative doubling time was calculated and the postoperative half-life time was estimated according to the diagnosis of metastases within 2 years after primary resection [metastasis (+) or (-)].
  
  
  RESULTS
  In spite of the effect of curative re-operation of metastatic lesions or of postoperative adjuvant chemotherapy, the CEA doubling time of the groups showed a relation with prognosis (p = 0.045, Student's t-test) when the patients were divided into >18 and < or =18 months survival time. The CEA half-life time of the groups without overlooked metastases was statistically longer than those with (mean +/- SD 8.01 +/- 2.07 and 4.33 +/- 1.11, respectively, p < 0.01, one-factor ANOVA test). Clearance (k) showed a significant difference between the groups (p < 0.001, Student's t-test).
  
  
  CONCLUSIONS
  The CEA doubling time appeared to be a less independent prognostic factor, whereas prolongation of the CEA half-life time might potentially suggest the existence of overlooked synchronous metastases from colorectal carcinoma.
authors.affiliation: Department of Surgery II, School of Medicine, Nagoya University, Nagoya, Japan. katsuki@tsuru.med.nagoya-u.ac.jp
authors.forename: Katsuki
authors.initials: K
authors.lastname: Ito
authors.forename: Kenji
authors.initials: K
authors.lastname: Hibi
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Ando
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Hidemura
authors.forename: Taiji
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Seiji
authors.initials: S
authors.lastname: Akiyama
authors.forename: Akimasa
authors.initials: A
authors.lastname: Nakao
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000556:secondary; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D002272:Carcinoembryonic Antigen / Q000097:blood*; D003110:Colonic Neoplasms / Q000473:pathology*; D005260:Female; D006207:Half-Life; D006801:Humans; D008113:Liver Neoplasms / Q000556:secondary*; D008175:Lung Neoplasms / Q000556:secondary; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen