ENO2 and Pleural effusion: However, there was no statistically significant difference between AUCs for tumour markers (S) CYFRA 21-1, (R) CEA, (P) CEA, (S) NSE, (P) NSE, (P) CYFRA 21-1 (data not shown) and therefore it cannot be concluded that any of them had greater diagnostic accuracy in distinguishing malignant from non-malignant pleural effusions.