Comparison of Rearranged During Transfection (RET) Gene Rearrangements in Primary Versus Metastatic Non-Small Cell Lung Cancer (NSCLC).

BACKGROUND RET rearrangements have been reported in 30% of papillary thyroid carcinomas and 1-2% of non-small cell lung cancer (NSCLC). In these tumors, RET gene fusion product provides a constitutively active tyrosine kinase (TKR), leading to uncontrolled cellular proliferation, differentiation, and migration. In this investigation we assessed the positivity rate of RET gene rearrangement in primary and metastatic non-small cell lung cancer and explored their relationships. MATERIAL AND METHODS Between January 2013 and May 2015, we collected 384 cases of primary metastatic non-small cell lung cancer, which included 246 matched metastatic tumors cases from multiple centers. The RET rearrangement uniformity in metastatic lymph nodes and tumor specimens were contrasted and the relationships between RET rearrangement and patients' clinical features were investigated. RESULTS For those 384 cases, 7 (1.82%) cases had tumors with identified RET rearrangement. Among the 246 paired cases, 3 (1.22%) cases of primary tumor had identified RET rearrangement and 2 (0.81%) cases of metastases had identified RET rearrangement. The sensitivity was 66.67% (2/3) and the specificity was 100% (243/243). CONCLUSIONS The results of this research indicate that the metastases of non-small cell lung cancer can predict RET rearrangement of the primary tumor tissue in the majority of cases. Testing for RET rearrangement in metastases can be used as an alternative to testing of primary tumor tissue if it is inaccessible.