OBJECTIVETo detect the presence of ROS1 fusion gene in pulmonary adenocarcinoma and its clinicopathologic parameters.

METHODSFluorescence RT-PCR was used to detect the presence of ROS1 fusion gene in 369 surgical resection samples of pulmonary adenocarcinoma with known EGFR mutation status. The presence of ROS1 fusion gene in correlation with clinicopathologic features was analyzed. Sixteen positive and 20 negative samples by RT-PCR were further confirmed by direct sequencing.

RESULTSROS1 fusion gene was detected in 16 of 369 lung adenocarcinoma samples (4.3%). The presence of ROS1 fusion gene was not correlated to gender, age, smoking history, tumor site, size, histological subtype, tumor differentiation, T staging, lymph node metastasis, TNM staging and EGFR mutation (P > 0.05). The frequency of ROS1 fusion gene was similar in female and male patients, 4.4% (8/183) vs 4.3% (8/186), P > 0.05. The presence of ROS1 fusion gene in patients of ≤ 60 years of age was higher than that in patients of > 60 years, 5.1% (10/195) vs 3.4% (6/174), P > 0.05. The rate of ROS1 fusion gene of non-smokers was a slight higher than that of smokers, 4.4% (14/318) vs 3.9% (2/51), P > 0.05. Both positive and negative cases were confirmed by direct sequencing in all cases.

CONCLUSIONSROS1 fusion gene occurs more frequently in younger and non-smoking patients of pulmonary adenocarcinoma, and may coexist with EGFR mutations. ROS1 fusion gene seems to define a distinct subset of pulmonary adenocarcinoma.