Multivariate analyses as aids to diagnosis and assessment of prognosis in gastrointestinal cancer.

The role of carcinoembryonic antigen (CEA), gamma glutamyl transpeptidase (gamma GT), phosphohexose isomerase (PHI), pseudouridine (psi) and acute phase reactant proteins (C-reactive protein (CRP) alpha 1-antichymotrypsin (ACT) and alpha 1-acid glycoprotein (AGP] in assessing the prognosis of gastrointestinal neoplasms and the discriminant function in distinguishing benign from malignant diseases of the GI tract was examined. In stomach cancer pre-operative levels of CRP can help in the identification of the patients with a resectable tumour; the pre-operative biochemical measurements do not give any further information on prognosis once stage and site are taken into account. In colorectal cancer pre-operative ACT levels give additional prognostic information once the clinical factors, Dukes stage, sex and age have been accounted for; PHI levels are on the border line of significance. A discriminant function has been devised using sex, CEA, psi, gamma GT, ACT and PHI that can identify 89% of Dukes "D" patients prior to surgery with a misclassification of 7% of other cases of colorectal cancer. A discriminant function using all the biochemical variates separated the cancer from non-cancer patients. The false positive rate for cancer was 16% and a false negative rate of 19%, when the cut-off level was set at 0.7.