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Z. Sou
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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
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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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): Z. Sou
- Abstract
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 characteristicsHistology 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.
