Diagnostic use of the sentinel node in colon cancer

PURPOSE: The aim of this study was to compare the lymphatic drainage of col on cancer with the anatomic distribution of histologic and submicroscopic l ymph node metastases. METHODS: Patients attending for colectomy were eligib le to enter the study. At the commencement of surgery, 40 MBq of 99mTc coll oidal antimony sulfide in 2 ml of Patent Blue dye was injected subserosally around the tumor. Resection was completed in a standard fashion. After res ection, specimens were imaged with a gamma camera to determine the site of sentinel lymph nodes, and then dissected, recording the position of the lym ph nodes on an anatomic diagram. Recovered lymph nodes were bisected, one-h alf for routine histology and one-half for assessment by keratin 20 (K20) r everse transcription polymerase chain reaction. The kappa measure of agreem ent was used to assess concordance between sentinel nodes and histologic an d submicroscopic metastases. RESULTS: Four hundred fifty-six lymph nodes we re dissected from 26 tumors and evaluated using lymphoscintigraphy and lymp h node mapping. Sentinel nodes were evident in 23 tumors (88 percent). The sensitivity of sentinel nodes involvement as a predictor of metastatic dise ase was 55 percent (95 percent confidence interval, 23-83), with a false ne gative (nondiagnostic) rate of 45 percent. Sentinel nodes involved the apic al group in four tumors, and represented anatomic "skip" lesions in four tu mors. CONCLUSIONS: Direct lymphatic drainage to the apical group does occur in colon cancer; however, sentinel node mapping of colon cancer by this te chnique is of little clinical value because of the poor concordance between lymph node metastases and sentinel nodes.