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D. Warren



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    P1.07 - Poster Session/ Small Cell Lung Cancer (ID 221)

    • Event: WCLC 2015
    • Type: Poster
    • Track: Small Cell Lung Cancer
    • Presentations: 1
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      P1.07-001 - Preoperative Serum proGRP as a Predictor for Lung Tumor Histology (ID 2561)

      09:30 - 09:30  |  Author(s): D. Warren

      • Abstract
      • Slides

      Background:
      Progastrin-releasing peptide (proGRP) is the stable precursor of gastrin-releasing peptide, a hormone secreted by neuroendocrine cells. Serum measurements of proGRP are helpful to detect relapses of small cell carcinoma during follow up, but its usefulness as a preoperative marker to distinguish between different lung tumors is unclear.

      Methods:
      Preoperative serum proGRP was determined in 116 patients with primary pulmonary tumors. 31% of the tumors displayed endocrine features (19 carcinoids, 8 small cell carcinoma, 9 large cell carcinomas) whilst the remainder were non-small cell carcinomas (40 adenocarcinomas and 40 squamous cell carcinomas). The presence of proGRP in tumors with possible endocrine features was evaluated by immunohistochemistry using two in-house anti-proGRP monoclonal antibodies (mAb M16 and mAb E149]. Tumors with less than 2 % positive cells were considered negative for proGRP expression. Serum levels of proGRP above 70 ng/L were considered elevated.

      Results:
      Mean serum proGRP (s-proGRP) was 267 ng/L (median: 96.5 ng/L, [range 25 – 2080 ng/L] for the neuroendocrine tumors, while adenocarcinomas and squamous cell carcinomas had mean values of 50 and 60 ng/L respectively [19,137] and median values 53.5 ng/L and 59.6 ng/L respectively (table 1). Among the tumors with possible endocrine features, serum levels of proGRP reflected the IHC score (Wilcoxon rank-sum test, p<0.0005). We did not find any relationship between tumor size and s-proGRP levels, but values >70 ng/L were predictive of either carcinoid tumor or small cell carcinoma. Table 1: Tumor characteristics

      Histology ProGRP IHC positives (n/total) S-proGRP (median) S-proGRP (mean) Mean tumor size (mm)
      Carcinoid 9/19 127 424 26.1
      Small cell carcinoma 5/8 75.5 145 30.2
      Large cell carcinoma 3/9 46 72.8 42.2
      Squamous cell carcinoma NA 59.6 60 NA
      Adenocarcinma NA 53.5 50 NA


      Conclusion:
      The correlation between s-proGRP and IHC scores suggest that the elevated s-proGRP results from proGRP produced by the tumor. The lack of correlation between s-proGRP and tumor size might be explained by variations in number of proGRP producing cells within the different tumors and/or to the amount proGRP secreted by different tumors. For lung tumors with unclear preoperative histology or cytology, s-proGRP-levels can be helpful as an adjuvant diagnostic marker to differentiate between tumors with and without endocrine features, but the test is not robust enough for final decision making.

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