Combined status of MUC1 mucin and surfactant apoprotein A expression can predict the outcome of patients with small-size lung adenocarcinoma

Aim: Lung cancer is still a disease of high mortality, despite advanced diagnostic techniques. Here, we aim to report a unique method to predict the recurrence and outcome of patients with pulmonary adenocarcinomas. Methods and results: Immunohistochemical expression of MUC1 mucin and surfactant apoprotein A (SP-A) was examined in 185 cases of surgically removed lung adenocarcinomas of non-bronchioloalveolar type smaller than 30 mm. Staining results were evaluated semiquantitatively, and the expression of MUC1 and SP-A was compared in each case. There were 140/185 (76%) cases showing MUC1 expression higher than SP-A expression (MUC1 > SP-A), and 45/185 (24%) cases showing MUC1 expression lower than or equal to SP-A expression (MUC1 less than or equal to SP-A). Recurrence was observed in 24% (34/140) of the patients with a MUC1 > SP-A pattern, but in 7% (3/45) of the patients with a MUC1 less than or equal to SP-A pattern after the median observation period of 41 months (1-99 months) (P < 0.01). The MUC1 > SP-A group showed higher recurrence and worse survival than the MUC1 less than or equal to SP-A group by Kaplan-Meier's method (P < 0.01 and P < 0.005). Even in the patients with apparently favourable prognostic factors (well-differentiated adenocarcinoma or no lymph node metastasis), recurrence and survival were different between the two groups. Conclusions: A high MUC1/SP-A ratio is strongly associated with a poor outcome in patients with small-size lung adenocarcinoma.