Utility of CT Scan and CA 19-9 in Predicting Non –Resectability in Malignant Obstructive Jaundice
Bitta C1, Githaiga J2, Kaisha W2
1. Webuye District Hospital
2. School of Medicine, University of Nairobi
Correspondence to: Dr Ceaser Bitta, P.O.BOX 25-50205 Webuye, Kenya. Email: cbittas@yahoo.com
 
Abstract
Background: Most patients with malignant obstructive jaundice (MOJ) present with non-resectable disease. Non curative laparotomy has been associated with adverse outcome. There is need to predict non-resectable disease and prepare patients for planned palliative procedures. Objective: To study the utility of Ca 19-9 serum levels and CT scan in predicting the non- resectability of MOJ tumours at Kenyatta National Hospital. Methods: Eligible consenting patients were recruited. All had a CT scan of the abdomen and serum CA 19-9 levels determined preoperatively and staging was done using the LRCC criteria. At surgery, intraoperative findings were then compared in terms of non-resectability with the preoperative CT scan prediction and the CA 19-9 levels. Results: A total of 49 patients were recruited into the study. During the study, 14 patients were later excluded due to inadequate information of imaging, non-surgical intervention or pre-operative death. At a confidence level of 95%, CA 19-9 level of 466 has 92.3% sensitivity and 100% specificity indicative of non resectability in MOJ lesions. When compared with intra-operative findings on non-resectability, the cut off level of 466 has a positive and negative predictive value of CA19-9 was 100% and 71.4%, respectively. CT scan had 85.2% sensitivity and 100% specificity on predicting non resectability of MOJ lesions, 84% sensitivity in detecting nodal involvement but predicted only 33% of liver metastases. Conclusion: Combining CA 19-9 levels and CT scan are useful tools in detecting non resectability of MOJ lesions preoperatively.
Key words: Malignant obstructive jaundice, non-resectability, CA 19-9, CT scan.

Introduction
Primary malignancies of the biliary tree and surrounding organs that cause Malignant Obstructive Jaundice (MOJ) include Cholangiocarcinoma, ampullary carcinoma, carcinoma of the head of pancreas and rarely gall bladder carcinoma. The incidence of MOJ tumours is increasing worldwide (1, 2, 3) . Despite the better diagnostic facilities available, the mortality and morbidity associated with these diseases still remains high. About 10-20% of patients with carcinoma of the pancreas (4) and less than 30% of those with cholangiocarcinoma (1, 5) have potentially resectable disease at presentation. Carcinoma of the ampulla of Vater has been associated with better prognosis with 50% of the patients having resectable disease at presentation, and better five year survival rate than cholangiocarcinoma and pancreatic carcinoma (3, 6). Complete surgical resection remains the only definitive curative procedure for these tumours. There is no improvement in outcome following incomplete surgical resection (7). Non curative resections have in fact been associated with higher morbidity and increased mortality rates (7, 8) . In patients with non resectable lesions, palliation of the biliary obstruction can be either by surgical bypass or non surgical procedures. In order to minimise the rate of surgical procedures that are neither curative nor palliative, the utility of several factors in predicting either the resectability or non resectability of MOJ lesions pre-operatively have been studied. The most frequently alluded to factors are tumour markers CA 19-9, CEA and the use of imaging modalities, more specifically contrast enhanced CT scan of the abdomen. Several authors have studied the utility of CA19-9 in predicting resectability of MOJ lesions with differing cut off values for resectability (9,10,11,) . CA 19-9 serum level is not a routine preoperative test for patients with obstructive jaundice at Kenyatta National Hospital. Several authors had questioned the sensitivity of CT scan in predicting resectability of MOJ lesions (12, 13). Others accept its utility (14, 15) with criteria for resectability being developed. (16). Our objective was to study the utility of pre-operative CA 19-9 and CT scan of the abdomen in predicting the non resectability of MOJ lesions.


Materials and Methods
Following institutional approval by the Kenyatta National Hospital (KNH) Ethics and Research Committee, all patients diagnosed with MOJ due to non-metastatic disease presenting at Kenyatta National Hospital during the period June 2009- March 2010 and consenting were enrolled into the study. Using the statistical formula below and an estimated local prevalence of 32.5 in 100000(based on previous local study indicating an incidence of 11.4 in 100000 for
Carcinoma of the pancreas (17) and international studies indicating that carcinoma of the pancreas account for approximately 35% of MOJ (18, 19)), a sample size of 33 would be the minimum required for the study.
N = Z² x p (1-p)

N = sample size to be determined
p = estimated prevalence of MOJ.
Z = standard errors of the mean corresponding to 95% confidence interval
d = Absolute precision (0.05)
The demographic characteristics for all the patients were noted. CA 19-9 levels were determined preoperatively at the KNH Biochemistry Laboratory and CT scan of the abdomen reported by a consultant radiologist. KNH uses Roche Cobas E411 immunology analyser with the Roche (South Africa) CA19-9 test kit based on the monoclonal 1116-NS-19-9 antibody. The London Regional Cancer Centre (LRCC) CT scan criteria were used for predicting resectability (absence of nodal metastases or other liver metastases, absence of involvement of portal vein/main hepatic artery/superior mesenteric artery involvement, absence of direct invasion of surrounding organs or disseminated disease). The surgeon was not aware of the patient’s preoperative CA 19-9 levels. The decision to intervene and the mode of intervention were exclusively made by the primary surgeon. The intra-operative findings were documented by primary surgeons, who were requested to document the visual presence and number of nodal metastases, vascular involvement/ encasement and peritoneal metastases in the operative notes. Biopsies of nodal and peritoneal metastases where possible were taken. This information was then used by the authors to determine potential tumour resectability as per the LRCC CT scan criteria. The form of surgical intervention was then documented. The post operative details of: hospital stay, other intervention, liver function tests (at 14 days), morbidity and mortality were documented.
The pre-operative CT scan and CA 19.9 were then compared with intra-operative findings for resectability and non-resectability.
Data collected was coded and entered into the SPSS(Version 17.0) software by a statistician. Descriptive statistics were done for all continuous variables, obtaining measures of central tendency and dispersions. Proportions of frequency were used for categorical variables. The chi-square test was used to determine association between the categorical independent variables and outcome (non resectability). Significance was set at 0.05


Results
During the study period a total of 49 patients were admitted to KNH with MOJ. Of these 30(61%) were female. The age range was from 34 to 81 years, with a mean of 62 (63 for females and 61 for males).
Of the 49 patients admitted, 32 had Carcinoma of the head of the pancreas (65%), 10 had Cholangiocarcinoma (21%) and 7 had peri-ampullary tumours (14%). During the study period, 45402 patients were admitted to KNH, of which 2737 patients were admitted to the general surgical units of KNH. As such for the period, the incidence of admission of patients with MOJ at KNH was 49:45402 (107:100,000) and into the surgical units was 41:2737 (14.9: 1000).