Clinical significance of CA19-9 in diagnosis of digestive tract tumors

Ji Zong Zhao,Bo Heng Wu

Subject headings  Digestive  system neoplasms; CA_19-9; tumor related antigen; stomach neoplasms; colorectal neoplasms; pancreatic neoplasms; esophageal neoplasms

Zhao JZ, Wu BH. Clinical significance of CAa-a  19-9aa in diagnosis of digestive tract tumors. China Nati J New Gastroenterol, 1997;3(4):253-254

Abstract

AIM  To evaluate the clinical value of CA_19-9 in diagnosing and differentiating the gastrointestinal tumors and in monitoring the patients treated surgically.

METHODS  Gastric cancer(n=70), colorectal cancer (n=90), pancreatic cancer (n=7), esophageal cancer (n=10), benign disorder (n=30), and normal adults (n=111) as control were studied. Fasting blood samples were obtained from each patient and normal adult. The serum CA_19-9 concentration was measured with radioimmunoassay.

RESULTS  The mean CA_19-9 level in gastric cancer (170.69kU/L¡À91.45kU/L) and in colorectal cancer (87.21kU/L¡À39.55kU/L) was significantly higher than that in the control (11.254kU/L¡À6.00kU/L). Compared with the normal adults, the CA_19-9 level was much higher in pancreatic cancer patients (1266.58kU/L¡À521.31kU/L) (P£¼0.01). However, the CA_19-9 concentrations in non recurrent gastric (12.63kU/L¡À3.62kU/L) and colorectal cancers (14.14kU/L¡À3.26kU/L) and benign disorders (14.23kU/L¡À2.60kU/L) were similar to the control. The differences were not statistically significant (P£¾0.05). The demarcation value of CA_19-9 between the negative and positive was £¼31.0kU/L. The sensitivity of CA_19-9 for gastric, colorectal, pancreatic and esophageal cancers and gastrointestinal benign disorders was 47.3%, 50.0%, 83.3%, 20.0% and 0%, respectively. The specificity of CA_19-9 for digestive system malignant diseases was all 100%.



INTRODUCTION
CA_19-9 antigen isolated by Koprowski and co-workers^£Û1£Ýin 1979, is a lacto N-fucopentaose ¢ò like substance and one of the tumorª²associated antigens present in serum in the mucin  fraction. Close attention has been paid to the role of CA_19-9 in  the diagnosis of digestive tract tumors^£Û2,3£Ý. After strictly inspecting the quality of CA_19-9 antigen kit, we assayed serum CA_19-9 levels in 207 patients with gastrointestinal diseases and 111 normal adults as control. The aim of this study is to evaluate the clinical significance of CA_19-9 in diagnosis of digestive tract tumors.

MATERIALS AND METHODS

Experimental equipment
CA_19-9 McAb solid phase IRMA kit (Tianjin SYTRON Biotech Inc.) FT-613 automatic counter of ¹²⁵I radioimmunoassay (Beijing)

Normal CA_19-9 value
We determined CA19-9 concentration in the sera of 111 normal adults from Guangzhou area as the normal referential value (55 male, 50 female, the mean age 47.7 years).

Patients
Serum samples were obtained from 207 patients with malignant and benign diseases  of digestive system. All diagnoses were confirmed by clinical, laboratory and pathological examinations. Of the 207 cases, 70 had gastric cancer, 90 colorectal cancer, 7 pancreatic cancer and 10 had esophageal cancer; and 30 had benign disorders, including 6 chronic superfical gastritis, 7 antral gastritis, 5 gastric ulcer, 10 duodenal ulcer and 2 acute appendicitis. There were 148 males and 59 females. The age ranged from 22 to 85 years, averaging 52.9 years.

RESULTS
The mean serum CA_19-9 concentration in 111 normal adults from Guangzhou area was 11.254kU/L¡À6.006kU/L. The difference of CA_19-9 value among normal adults has no statistically significance with age and sex (P£¾0.05). The demarcation value of CA_19-9ªª between the negative and positive was £¼31.0kU/L in our laboratory. The serum CA_19-9 concentrations in patients with malignant and benign diseases are listed in Table 1. Table 2 shows the evaluational indexes of CA_19-9 in diagnosing some of the gastrointestinal tumors.
Table 1  Serum CA_19-9 concentration in patients and normal adults

^aP£¼0.05 vs normal adults, ^bP£¼0.01 vs normal adults; P.R=positive rate.
Table 2  The evaluational indexes in diagnosis of gastrointestinal benign and malignant diseases with CA_19-9

Se: Sensitivity, Sp: Specificity, Ac: Accuracy, +PV: Positive predictive value, £­PV: Negative predictive value.

DISCUSSION
We have determined the normal referential value of CA_19-9 (11.254kU/L¡À6.006kU/L) with solid phase IRMA kit (Tianjin SYTRON) in 111 normal adults from Guangzhou area. This result was similar to the results tested with solid phase radioimmunoassay kits of Abbott Company and ORIS Company, (France). The demarcation value of CA_19-9 between the negative and positive was £¼31.0kU/L. This value was a little lower than that provided by the kit (£¼34.0kU/L).
    The results showed that the serum CA_19-9 levels in the patients with gastric cancer (55), colorectal cancer (66) and some postoperatively recurrent cancer were significantly higher than those of normal adults. The sensitivity of CA_19-9 in diagnosing gastric and co-lorectal- cancers was 47.7% and 50.0% and the specificity and positive predictive value were all 100%. None of the 30 patients with benign disorders of gastrointestinal tract had a higher serum CA_19-9 level than the normal referential value. The sensitivity and specifity of CA_19-9for benign disorders were 0% and 100%, respectively. This indicated that CA_19-9 is a high specific tumor marker in diagnosing gastric and colorectal cancers, and will play an important role in the differentiation of benign and malignant diseases of digestive tract.ª¥
    It is worth notice that of 39 patients with gastric cancer or co-lorectal-cancer who had no recurrent tumor postoperatively, no one had a higher CA_19-9 level than normal referenial value. The mean value of CA_19-9 of the 39 patients was similar to the normal ref erential value. However, the serum levels of CA_19-9 in 9 patients with recurrent gastric cancer and 16 with recurrent colorectal cancer postoperatively were significantly higher than the normal referential value. The positive rate of CA_19-9 in recurrent gastric and colorectal cancers was 77.8% and 68.7%, respectively. The CA_19-9 level reached 2500kU/L in a few patients with recurrent tumors. The results showed that CA_19-9 was a good index in evaluating the effect of treatment and predicting the prognosis of gastric and colorectal cancers postoperatively.
    Elevated serum CA_19-9 levels have been found in many different malignant diseases. The test seems expecially promising for detection of pancreatic cancer, as more than 80% of these patients showed increased serum CA_19-9 concentration^£Û4,5£Ý, therefore it may be a good tumor marker in diagnosing pancreatic cancer and monitoring the patients treated surgically^£Û6£Ý. We assayed the CA_19-9 levels  in patients with pancreatic cancer, and the serum CA_19-9 concentration was £¾85kU/L in 6 £¾110kU/L in 5 patients, £¾1900kU/L in 3 patients and 3200kU/L in one patient. The sensitivity, speciticity, accuracy, positive and negative predictive values were 83.3%, 100%, 97.3%, 100%, 96.8%, respectively.
    The incidence of pancreatic cancer is increasing worldwide. The Japanese Cancer Register in 1987 reported that the 5-year survival rates in 177 resected cases of T₁ stage, 783 resected cases of T₂ stage, 463 resected cases of T₃ stage and 304 resected cases of T₄ stage cancer were 39.8%, 21.7%, 14.3% and 13.4% respectively^£Û7£Ý. These results indicate that it is important to diagnose early stage pancreatic cancer so as to improve the prognosis. However, by the current diagnostic methods, it is difficult to diagnose pancreatic cancer in early stage, and to distinguish it from benign condition which resembles pancreatic cancer in many aspects. Although only 7 patients with pancreatic cancer received the CA_19-9 test in this study, the results still showed that the CA_19-9 test seems to be a useful additional tool in the diagnosis of pancreatic cancer.

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The First Affiliated Hospital, SUN Yat Sen University of Medical Sciences, Guangzhou 510080, China
Correspondence to Dr. Ji Zong Zhao, male, was born on Jan. 22, 1945 in Guangzhou, graduated from Department of Laboratory Medical Sciences, Guangzhou Medical Collage, Laboratorian in Charge, engaged in laboratory diagnostic study on clinical chemistry and immunology, having 15 papers published.
Tel:+86¡¤20¡¤87755766
Received  1996-09-06    Revised  1996-10-05