Tumor characteristics, expressions of ERCC1, Bax, p53, IGF1R, Bcl2, Bcl2/Bax and prognostic factors for overall survival in patients with lung carcinoid

PURPOSE: Neuroendocrine lung tumors (NET) include typical carcinoids (TC), atypical carcinoids (AC), large cell NE carcinoma (LCNEC) and small-cell carcinoma (SCLC), with different clinicopathological profiles and relative grades of malignancy. Although differences between carcinoids and high grade carcinomas are recognized, precise differences and behavior of TC and AC have not been clearly defined. The aim of this study was to better define the differences in the clinical behavior of TC and AC, and to establish new prognostic factors of overall survival (OS), by determining the levels of genetic expression of IGF1R, ERCC1, Bax, p53, Bcl2 and Bcl2/Bax ratio.

METHODS: The histopathological diagnosis of 52 surgically resected pulmonary carcinoid tumors was made according to the WHO classification. Gene expressions were evaluated by quantitative real-time PCR.

RESULTS: The confirmed prognostic factors for overall survival (OS) were pTNM T (p<0.01), pTNM N (p<0.05), clinical stage (p<0.05), type of surgery (p<0.01) and histopathological (HP) tumor type (p<0.05). Bcl2 mRNA level and Bcl2/Bax ratio were found to have a potential for discrimination of the HP type of tumor (AC vs TC, Receiver Operating Characteristics (ROC) cut-off values 0.1451 and 0.3015, respectively), but without statistically significant impact on OS.

CONCLUSIONS: In patients with NETs, smaller primary tumor, absence of positive lymph nodes, and TC type of tumor predicted longer OS. Type of resection has influence on OS. Bcl2 expression and Bcl2/Bax ratio might be valuable as independent diagnostic parametars in lung carcinoids. Therapeutic approaches using attenuation of Bcl2 or upregulation of Bax might prove useful in lung NETs.