AIM: To explore the relationship between the expression of transforming growth factor-?1 (TGF-?1) and the pathogenesis of lung carcinoma, and the influence of radiotherapy on plasma TGF-?1 level of patients with lung carcinoma. METHODS: By immunohistochemical method, the expression of TGF-?1 was examined. An enzyme-linked immunoadsorbent assay (ELISA) was used to quantify the plasma TGF-?1 levels in different time as before radiotherapy, at the end of radiotherapy, and at the time of follow-up 6 months after radiotherapy, respectively. The changes of quantity of TGF-?1 in different time above were analysed statistically. RESULTS: There was a significant increase in TGF-?1 expression in the carcinoma compared with normal lung tissue. The mean TGF-?1 level in the 39 lung carcinoma patients before radiotherapy was (11 0?1 5) ?g/L, which was significantly higher than control group (3 8?0 2 ?g/L) ( P 0 05). At the time of follow-up 6 months, the patients of lung carcinoma had a significantly higher plasma TGF-?1 level (11 3?1 2 ?g/L) compared with the level at the end of radiotherapy ( P 0 05). Not significant difference was found in TGF-?1 levels among different histologic types. CONCLUSION: These data demonstrated that TGF-?1 was associated with the pathogenesis of lung carcinoma, and it may be a useful tumor marker in patients with lung carcinoma. [