Clinical Significance of Cancer Serum Index in Colorectal Cancer

Masaru Fujimori

Department of Surgery, Obihiro Kohsei Hospital

The cancer serum index (CSI) was determined by single radial immunodiffusion in 120 patients with colorectal cancer and compared with serum carcinoembryonic antigen (CEA) in order to investigate its clinical significance. The CSI increased with advance of the clinical stage of the cancer. When 2.20 was defined as the cut-off value for a positive CSI, the index was positive in 77.5% of the patients with the cancer, but also positive in 86.1% of patients with inflammatory gastrointestinal disease. The CSI correlated with the maximum diameter of the tumor, serosal invasion or extensive nodal metastasis. On the other hand, CEA was not correlated with the maximum diameter of the tumor, but it was closely correlated with liver metastasis. Both CSI and CEA were significantly higher in patients who received a non-curative operation than in those given a curative operation. However, 22.7% of the non-curative operation group showed normal CEA values. CEA was positive earlier than the CSI in all the patients with recurrence after a curative operation. Therefore it is concluded that the CSI is not suitable for a screening test for colorectal cancer nor a monitoring test for detection of recurrence after surgery, but that a combination assay of both CSI and CEA is useful for evaluation of the clinical stage and for forecasting operative curability in colorectal cancer.

Key words
cancer serum index, single radial immunodiffusion, colorectal cancer, carcinoembryonic antigen, combination assay

Reprint requests
Masaru Fujimori Department of Surgery, Obihiro Kohsei Hospital
South-8, West-6, Obihiro, 080 JAPAN

Accepted
April 17, 1991

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