Surgical results of non-ampullary duodenal cancer: a nationwide survey in Japan.

BACKGROUND: As non-ampullary duodenal cancer is relatively rare, the optimal treatment strategy, including the appropriate surgical procedure and efficacy of adjuvant chemotherapy, remains unclear. This nationwide survey aimed to clarify the actual lymph node spread pattern and determine the optimal treatment strategy for this disease, using a large-scale database. METHODS: We used a questionnaire and a retrospective registry of 1083 patients with non-ampullary duodenal cancer who had undergone surgery during 2008-2017 in 114 high-volume Japanese Society of Hepatobiliary and Pancreatic Surgery-certified training institutions. Propensity score-matched analyses were conducted to minimise background bias. Cox regression was performed to identify covariates associated with recurrence-free survival. There were distinct disparities in the nodal dissection rate according to the predominant tumor location and tumor invasion depth. Metastases were frequently observed in the peripancreatic nodes and those along the superior mesenteric artery, irrespective of tumor location. Their dissection seemed to be beneficial for improved survival. In the overall cohort, no survival benefit was observed in patients who received adjuvant chemotherapy when compared with that in patients who underwent surgery alone. Nevertheless, in the matched cohort, adjuvant chemotherapy for > 6 months was associated with a significant improvement in recurrence-free survival (median: 43.5 vs. 22.5 months, p = 0.016), particularly in patients with tumor invasion of the subserosa or deeper tumor invasion, lymph node metastasis, or elevated serum carbohydrate antigen 19-9 levels. CONCLUSION: Pancreatoduodenectomy should be the standard procedure for advanced non-ampullary duodenal cancer. Adjuvant chemotherapy for > 6 months, especially for advanced tumors, significantly improves survival.