[1572] Immunohistochemical Expression of Progesterone Receptor in Neuroendocrine Tumors: Expression Is Present Predominately in Low-Grade Pancreatic Endocrine Neoplasms

JS Estrella, H Wang, MW Taggart, SC Abraham, A Rashid. MD Anderson Cancer Center, Houston, TX

Background: Previous studies have reported immunohistochemical expression of progesterone receptor (PR) in neuroendocrine tumors of different sites. However, the prognostic significance of PR expression in neuroendocrine tumors has not been studied.
Design: We investigated the immunohistochemical expression of PR in 133 neuroendocrine tumors, including 71 pancreatic endocrine neoplasms (PENs), and 45 gastrointestinal and 17 lung carcinoid tumors using tissue microarray. Statistical analyses were done using Fisher's exact test, T-test and overall survival by log-rank method.
Results: Thirty-eight of 71 (51%) PENs showed positive PR immunohistochemical staining compared to 2 of 45 (4%) gastrointestinal and 0 of 17 (0%) lung carcinoids (p=0.0001). In PENs, PR expression was significantly associated with WHO grade and size of tumors. PR staining was present in 14 of 15 (93%) WHO grade 1A, 7 of 8 (88%) grade 1B, 16 of 44 (36%) grade 2 and 0 of 5 (0%) grade 3 tumors (p=0.0001). PR positive PENs averaged 2.9 ±0.3 cm versus 5.5 ±0.7 cm for PR negative PENs (p=0.001). MEN-1 associated PENs were more frequently PR positive (88%) compared to sporadic tumors (48%), however, the data was not statistically significant (p=0.057). The mean overall survival of patients who had PR positive PENs was 272 ±42 months compared to 116 ±13 months for patients with PR negative PENs, although statistical significance was not met (p=0.08).
Conclusions: In neuroendocrine tumors, PR expression is present predominately in smaller WHO grade 1 PENs, and PENs in syndromic patients. PR positivity may help in differentiating benign from aggressive PENs in a biopsy specimen and may help to ascertain site of origin of metastatic low-grade neuroendocrine carcinomas.
Category: Liver & Pancreas

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 220, Tuesday Afternoon


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