The tumor cells showed positivity for neuroendocrine markers such as synaptophysin (Fig. 3a), chromogranin A (Supplementary Fig. 1a) and insulinoma-associated protein 1 (INSM1) (Supplementary Fig. 1b) with a Ki-67 index of 60.6%, indicating the cells to be NEC. Here, INSM1 is linked to neuroendocrine carcinoma.