Lymph Node Mapping in Transverse Colon Cancer Treated Using Laparoscopic Colectomy With D3 Lymph Node Dissection

BACKGROUND: Laparoscopic surgery for transverse colon cancer has been excluded from 7 randomized trials for various reasons. The optimal procedure for transverse colon cancer remains controversial. OBJECTIVE: This study aimed to analyze the patterns of lymph node metastasis in transverse colon cancer and to report short- and long-term outcomes of the treatment procedures. DESIGN: This was a single-center retrospective study. SETTINGS: This study was conducted at Cancer Institute Hospital, Tokyo, Japan. PATIENTS: We enrolled 252 patients who underwent laparoscopic surgery for transverse colon cancer. INTERVENTIONS: The transverse colon was divided into 3 segments, and the procedures for transverse colon cancer were based on these segments, as follows: right hemicolectomy, transverse colectomy, and left hemicolectomy. MAIN OUTCOME MEASURES: Postoperatively, the surgeons identified and mapped the lymph nodes from specimens and performed formalin fixation separately to compare the results of the pathological findings. RESULTS: For right-sided, middle-segment, and left-sided transverse colon cancers, the frequency of lymph node metastases was 28.2%, 19.2%, and 19.2%. Skipped lymph node metastasis occurred in right-sided and left-sided transverse colon cancers but not in middle-segment transverse colon cancers. The pathological vascular invasion rate was significantly higher in right and left hemicolectomy than in transverse colectomy. For right hemicolectomy, transverse colectomy, and left hemicolectomy, 5-year overall survival rates were 96.3%, 92.7%, and 93.7%, and relapse-free survival rates were 92.4%, 88.3%, and 95.5%. In multivariate analysis, the independent risk factor for relapse-free survival was lymph node metastasis. LIMITATIONS: Selection bias and different backgrounds may have influenced surgical and long-term outcomes. CONCLUSION: Laparoscopic surgery for transverse colon cancer may be a feasible technique. Harvested lymph node mapping after laparoscopic resection based on D3 lymphadenectomy may help guide the field of dissection when managing patients who have transverse colon cancer. The only independent prognostic factor for relapse-free survival was node-positive cancer.