Background: The presence of gastric cancer cells in the peritoneal cavity detected by cytologic examination is an important prognostic factor. A reverse transcriptase-polymerase chain reaction (RT-PCR) technique amplifying carcinoembryonic antigen mRNA was recently introduced to detect these cells more sensitively.
Study design: Five-year followup was completed for 284 gastric carcinoma patients who underwent CEA RT-PCR testing. Analyses to assess the accuracy and prognostic value of this procedure were performed, along with univariate and multivariable analyses to evaluate RT-PCR as a technique with peritoneal carcinomatosis and cancer death as the outcomes variables.
Results: CEA mRNA levels exceeded the cutoff value defining a positive result in 9.5%, 29%, 66%, and 81% of patients with pT1, pT2, pT3, and pT4 stage disease, respectively. Sensitivity, specificity, positive predictive value, and negative predictive value for peritoneal carcinomatosis within 5 years of surgery were 88.5%, 81.6%, 64.5%, and 94.9%, respectively. Multivariable analysis revealed that a positive CEA mRNA result was an independent risk factor for cancer death (hazard ratio 2.82, 95% CI 1.17 -3.07) among 274 patients (10 patients with no record of nodal status were excluded from the analysis) and for peritoneal carcinomatosis (hazard ratio 1.57, 95% CI 1.07-2.29) among 242 patients who had no peritoneal deposits at operation.
Conclusions: CEA RT-PCR is useful as a prognostic marker for increased risk of cancer death and peritoneal carcinomatosis, and might be useful in the clinical setting for selecting patients for various adjuvant treatments.