Mismatch Repair (MMR) Protein Expression is Uncommon in Poorly Differentiated Neuroendocrine Carcinoma

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Introduction: Microsatellite instability (MSI) has been reported to occur in a significant proportion of neuroendocrine carcinoma (NEC) and mixed adenoneuroendocrine carcinomas (MANEC) (11 out of 89 cases, Sahnane et al, ERC 2015). It might be predictive of response to immunotherapy.

Aim(s): To evaluate MMR protein expression by immunohistochemistry (IHC) in a series of consecutive patients with metastatic NEC.

Materials and methods: Fourteen cases of NEC were studied, including 9 gastroenteropancreatic, 2 thoracic, 1 bladder, 1 head-and-neck and 1 from unknown primary. IIHC for MSH2, MSH6, MLH1 and PMS2 was performed on paraffin embedded tissue, prior to therapy and interpreted according to current recommendations. Primaries (n=6) or metastases (n=8) were analyzed.

Conference: 14th Annual ENETSConcerence (2017)

Presenting Author: Hadoux J

Authors: Hadoux J, Malka D, Berdeloux A, Planchard D, Boige V,

Keywords: Neuroendocrine carcinoma, mismatch repair, microsatellite instability,