J.Jpn. Surg. Soc.. 122(2): 172-178, 2021

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Feature topic

BORDERLINE/MARGINALLY RESECTABLE PANCREATIC NEUROENDOCRINE TUMORS

Pancreatic neuroendocrine neoplasms (PanNENs) with local extension corresponding to the definition of borderline resectable pancreatic cancer are often resectable, as their growth rate is usually slow and they are rarely associated with aggressive local invasion. However, due to the heterogeneity of the tumors, they may be highly fibrotic and have the same resectability limits as pancreatic cancer. The pathogenesis of marginally resectable tumors is more important than the negativity of the resected margins because: 1) there is a high rate of liver metastases of portal vein tumors, even when tumor resection and portal vein colectomy are feasible; 2) resection of more than 70％ of metastatic lesions of the liver offers a better prognosis than nonresection, although recurrence is inevitable; and 3) resection alone is not superior to nonresection for neuroendocrine carcinoma (NEC). In terms of the need for additional treatment, portal vein tumor thrombus, liver metastases, and NEC are defined as marginally resectable. Although not approved in Japan, capecitabine + temozolomide and peptide receptor radionuclide therapy have been reported to reduce the size of tumors and improve progression-free survival rates. These novel therapeutic options are potential candidates for the neoadjuvant treatment of PanNENs.

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