Distribution of lymph node metastasis and prognosis in duodenal bulb tumors: A multicenter retrospective study.

797 Background: Duodenal tumors, especially duodenal bulb tumors, is a relatively rare malignancy of the gastrointestinal tract. The optimal surgical procedure for primary duodenal tumors has not been established because of its low incidence. The purpose of this study was to examine the distribution of lymph node (LN) metastasis in duodenal bulb tumors. Specifically, in T1a and T1b tumors, we aimed to evaluate the feasibility of distal gastrectomy with duodenal bulb resection combined with lymphadenectomy of regional gastric LNs. Methods: Data from patients who underwent surgery for either adenocarcinoma or neuroendocrine tumor located in the duodenal bulb between 2000 and 2020 were retrospectively analyzed from five high-volume centers in Japan. Patient background, clinicopathological factors, type of surgery, distribution of LN metastasis, and long-term outcomes were evaluated. Results: Of the 128 patients evaluated, LN metastasis was observed in 36%. The frequency of LN metastasis in T1b was 18%. Metastatic LNs were identified in #3, #5, #6, #8a, #8p, #12a, and #13 in T1b. The distribution of LN metastasis in T1b was similar between adenocarcinoma and neuroendocrine tumors. The 3 years overall survival rate in T1a, T1b, and T2–4 was 100%, 93%, and 64%, respectively. ln T1b, while there were three patients with a recurrence, two cases were observed in distant organs without regional LNs, and one patient who underwent pancreaticoduodenectomy had metastasis in the gastric regional LNs. Conclusions: Based on the distribution of LN metastasis with pT1, distal gastrectomy with duodenal bulb resection and regional LN dissection is considered a curative treatment. Conversely, pancreaticoduodenectomy is recommended in tumors with T2 or deeper.