They were as follows: ESR (OR = 0.36, 95% CI = 0.221–0.579), effusion CEA (OR = 20.51, 95% CI = 10.24–44.44), effusion CA19-9 (OR = 3.218, 95% CI = 1.737–6.042), effusion CYFRA21-1 (OR = 3.56, 95% CI = 2.074–6.177), PF/serum CEA ratio (CEA ratio; OR = 5.019, 95% CI = 2.97–8.577), effusion ADA (OR = 0.2, 95% CI = 0.071–0.535), and serum LDH/effusion ADA ratio (cancer ratio, CR; OR = 4.458, 95% CI = 1.738–11.86) (Table 2). Here, ADA is linked to cancer.