From October 2017 to December 2018, 42 cases of LAD and paracancerous tissues (> 3 cm away from tumor tissues) were collected from patients diagnosed with LAD (25 males and 17 females), all of whom were pathologically confirmed and surgically treated at the Second Hospital of Jilin University. Of the 42 cases, 29 cases were under 55 years and 13 cases were over 55 years. The tumor tissues were either classed as well differentiated (n = 20), moderately differentiated (n = 12), or poorly differentiated (n = 10). Moreover, lymph node metastasis was detected in 16 cases while no such findings were identified in the remaining 26 cases. According to latest staging system for lung cancer published by the International Union Against Cancer and American Joint Committee on Cancer [14], the enrolled cases were further divided into stage II (n = 27) and stage IIIa (n = 15). Patients who received any medication, radiochemotherapy or immunobiological therapy were excluded from the study.