Estimation of serum level of pS2 protein in patients with lung adenocarcinoma

We measured pS2 protein in the serum of patients with adenocarcinoma and non-adenocarcinoma types of lung cancer, non-cancerous lung lesions, and the control sera. Although the serum pS2 protein level in patients with lung adenocarcinoma was significantly higher than that in patients with other diseases, as well in control samples, it had little clinical value as a screening tumor marker because the levels in control samples showed a wide range of variation. However, analysis according to the histological subtype of lung adenocarcinoma, ordinary and bronchioloalveolar, revealed a high serum level of pS2 protein in several patients with advanced stage disease in the former, and mucus-producing goblet cell subtypes in the latter, which showed strong pS2 protein expression in tissues, whose serum levels diminished to the control level after resection. Thus, the serum levels of pS2 protein may be a useful marker of tumor burden in selected patients with lung adenocarcinoma.