Валидноста на сентинелниот лимфен јазол кај пациенти со колоректален карцином изолиран со употреба на радиоактивен колоид на Tc99m

Abstract

Introduction: The presence of metastasis in the regional lymph nodes is the most important prognostic factor in patients with colorectal cancer. The identification of the sentinel lymph node could significantly improve the accuracy of the analysis and the definite diagnosis in this patients and would undoubtedly influence the decision on appropriate therapy. The goal of this doctoral thesis is to evaluate the validity of the sentinel lymph node in colorectal cancer patients by using the Tc99m marked colloid, as well as the percentage of upstaging when applying histopathological analysis using immunohistochemistry. Material and methods: This study has been designed as a prospective controlled study at the University Clinic for Digestive Surgery in Skopje in the period of 30 months (in 2013-2015). All patients included in the study have signed an informed consent form. The Tc99m colloid has been injected around the tumor submucosaly, through endoscopy in the amount of 4 ml or one dose of 148 MBq. After the application a selective abdominal imaging on gama camera has been done to detect the distribution of the colloid through the lymph nodes to the sentinel node. The patients have been operated on the next day using a standard surgical technique involving complete regional lymphadenectomy. Using a gamma scintillation probe the most radioactive sentinel lymph node was detected and isolated ex vivo, and directed for histopathological analysis which applied not only the standard staining but also immunohistochemistry to detect the micrometastases. Results: This prospective controlled study involved 94 patients and 34 of them who have met all inclusion and exclusion criteria have been subjected to a complete clinical protocol. In all patients at least one sentinel lymph node was identified (median number 1.17) which makes for a 100% detection rate. In 31 out of 34 patients the sentinel lymph node has accurately predicted the status of the rest of the regional nodes which makes the accuracy of the method to be at 91.1%. With 3 patients there was a false negative resoult (the sentinel node was negative while some of the other regional nodes were positive) which makes the sensitivity of the method to be 80% while the negative predictive value is 86.36%. Using immunohistochemistry helped detect micrometastases in 2 patients which would have remained undetected if standard hemotoxillin/ eosin staining has been applied. Since 15 patients in this study have been N(+) while 19 N(-) using conventional staining, this has contributed to the upstaging of 10.5% of the patients. In 3 patients the sentinel node, from all the isolated nodes, was the exclusive location where metastases were detected. Aberrant lymphatic drainage was not detected in any of the patients in this study. Conclusion: The identification of the sentinel lymph node in colorectal cancer applying the radioactive Tc99m colloid is possible, simply done and provides great sensitivity, while its negative predictive value is similar to the other methods that use blue dye as a mapping agent. The extent of the usefulness of sentinel node identification should be researched in bigger in size, randomized and multi-centric studies and for the time being the clinical decisions on interpreting the detected micrometastasis remain controversial and should be limited to clinical studies. Nevertheless in the era of minimally invasive medical procedures we believe that the concept of sentinel lymph node in colorectal cancer will gain its importance and find its place among the arsenal of clinical options for fighting this terrible disease.