“…During the past several decades, many researchers carried out a series of studies try to clarify the relationship between NO and lung cancer. These studies were mainly about comparisons of the levels of FeNO and blood NO between lung cancer patients and healthy controls , among lung cancer patients with different stages [7-9, 14, 17-21, 23, 27, 29, 31, 34, 36-39, 42] or types [6, 8, 9, 18-21, 24, 26, 27, 29, 31, 37-39, 42], and variations of these indexes from pretreatment to posttreatment [7,10,14,19,21,29,32,34,36,38,39,43,[46][47][48][49][50][51][52][53][54][55]. However, the results were not consistent among different studies, which might be due to ethnicity, age, pathological type, cancer stage, treatment regimen and follow up period.…”