Endocrine Abstracts

A positive expression of oestrogen-receptors has recently been demonstrated in pancreatic neuroendocrine tumours as well as in non-neoplastic islet-cells. This prompted us to systematically analyse the expression of both oestrogen and progesterone receptors in a series of GEP neuroendocrine tumours. We analysed oestrogen- and progesterone-receptor in 69 foregut GEP, 25 midgut GEP and seven hindgut GEP. Namely, the foregut GEP included 53 pancreatic NET. All tumour samples were evaluated by to pathologist and a consensus immunoreactivity score according to Remmele (0–12) was assigned. An immunoreactivity score ≥2 was regarded as positive. According to the definition above 17% of the samples were oestrogen-receptor and 46% were progesterone-receptor positive. When we compared pancreatic NET to all other GEP-NET as well as to foregut, midgut and hindgut NET, the expression of oestrogen-receptor did not differ significantly between the groups. However, expression of the progesterone-receptor was more frequently expressed in pancreatic NET than in the other GE-NET (81% vs 8%, P<0.0001). This difference remained statistically significant, when pancreatic NET were compared to foregut NET (81% vs 13%, P<0,0001), to non-pancreatic midgut NET (81% vs 8%, P<0,0001) and to hindgut NET (81% vs 14%, P=0,0039). To evaluate the potential role of oestrogen/progesterone receptors in metastasis we evaluated biospies of 83 metastases from 45 cases. Oestrogen-receptor expression was rare (IRS ≥2 in three nodal metastases of pNET and four nodal metastases of non-pNET). In contrast, progesterone-receptor expression was found in only one nodal metastases of non-pancreatic origin, but 15 metastases of pNET stained positive for the progesterone receptor. In summary, our data indicate a potential role of progesterone-receptor expression in the metastatic process and its determination may help to identify the primary in cases of NET-metastasis of unknown primary.

Disclosure: The study was supported by an unrestricted educational grant from IPSEN Pharma GmbH (Ettlingen), Germany.