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Chulalongkorn Medical Journal

Abstract

Background and Rationale : Colorectal cancer is a common malignancy of thegastrointestinal tract. In Thailand, colorectal cancer isthe third most common cancer in males and fifth mostcommon in females. Incidence rate of colorectal cancerhas been rising in Thailand. Pathologic staging is the goldstandard for colorectal cancer. However, it is followed bypost-operative procedure. Computed tomography (CT) isnoninvasive and preoperative assessment. Preoperative CTis useful for planning therapy by which local extension ofthe tumor into the adjacent organs or distant metastasesare demonstrated. Differentiation between T2 and T3 coloncancer is important for consideration of chemotherapy.Objective : To compare the multi-detected computed tomography(MDCT) of the whole abdomen for colorectal cancer stagingcorrelated with pathologic staging including the accuracyof the staging of the tumor (T) and lymph nodes (N).Research design : Retrospective descriptive study.Setting : Department of Radiology, Faculty of Medicine, ChulalongkornUniversity and King Chulalongkorn Memorial Hospital.Material and Methods : Abdominal MDCT scans of 178 patients with pathologicdiagnosis of colorectal cancer were retrospectively reviewedfrom 1st January 2007 to 31st December 2009 at KingChulalongkorn Memorial Hospital.Result : Agreement of CT for T staging is good with excellentinterobserver agreement. The overall accuracy of correctT stage from CT scan was 75.84%. All overstaged CT scanswith pathologic stage < T2 were pericolonic fat strandingdue to mitoses, necrosis, mucin producing area, anddesmoplastic reaction around the sheet of tumor frompathological reports. The causes of overstaging by CT scanwith pathologic stage T3 were obliteration of fat plane ofadjacent organs in 4 lesions, abutting peritoneum in 6 lesions,ascites in 1 lesion, and colonic perforation in 2 lesions. Allcases of understaging by CT scan with pathologic stage T3were no pericolonic fat stranding and 2 cases of understagingby CT scan with phathologic stage T4 were preserved fatplane between the mass and adjacent organs. The highestsensitivity, NPV and accuracy are stage T4 (86.4%, 97.8%and 89.9%, respectively). The highest specificity is stageT < 2 (92.3%). The highest PPV is stage T3 (90.3%).Agreement of CT for N staging is poor with good interobserveragreement. The overall accuracy of correct N stage fromCT scan was 32.27%. The highest sensitivity is stageN0 (63.8%). The highest specificity, PPV and accuracy arestage N2 (99.1%, 83.3% and 64.6%, respectively).The highest NPV is stage N1(74.6%).Conclusion : CT scan is useful in preoperative evaluation of colorectalcancer. In our study, colorectal cancer staging fromCT scan is considered satisfactory for tumor staging, buttoo low to determine the nodal staging. The overall accuracyof correct T stage by CT scan was 75.84%.

Publisher

Faculty of Medicine, Chulalongkorn University

First Page

659

Last Page

674

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