Table 1. Overall results of meta-analysis by tumor type and statistical model used.

Tumor	No. of studies	Point estimate	95% CI of point estimate	Heterogeneity, I2	Model used
Bladder - serum	2	−1.24	−1.77 to −0.71	61.74	random
Breast serum	12	−0.93	−1.68 to −0.17	96.16	random
Breast tissue	15	1.80	1.17 to 2.42	94.89	random
Colorectal serum	5	0.04	−2.57 to 2.64	98.98	random
Colorectal tissue	7	0.37	−0.97 to 1.72	96.23	random
Esophageal serum	4	−2.17	−3.23 to −1.11	86.46	random
Esophageal tissue	3	−1.57	−3.17 to 0.03	94.72	random
Gallbladder - serum	1	−2.31	−2.96 to −1.65		-
Gallbladder - tissue	2	−1.25	−1.73 to −0.77	0.00	fixed
Gynecological serum	3	−0.39	−0.6 to −0.17	49.48	fixed
Gynecological tissue	4	−0.70	−1.85 to 0.45	91.40	random
Head and neck tissue	2	3.11	−5.96 to 12.17	98.75	random
Head Neck serum	5	−1.43	−2.17 to −0.68	77.46	random
Kidney - tissue	4	−2.23	−3.89 to −0.57	89.51	random
Liver - serum	3	−2.29	−5.21 to 0.63	97.64	random
Liver - tissue	7	−8.26	−11.02 to −5.49	98.49	random
Lung - serum	13	−1.04	−1.53 to −0.56	92.94	random
Lung - tissue	6	−3.12	−4.57 to −1.67	96.76	random
Prostate serum	7	−1.36	−1.97 to −0.75	97.93	random
Prostate tissue	12	−3.90	−5.26 to −2.54	94.67	random
Stomach serum	4	−1.59	−3.14 to −0.03	98.24	random
Stomach tissue	3	−0.79	−1.44 to −0.14	60.85	random
Thyroid serum	3	−0.62	−3.04 to 1.79	97.69	random
Thyroid tissue	3	−2.84	−5.39 to −0.29	97.56	random
Overall - serum	58	−1.08	−1.33 to −0.82	96.71	random
Overall - tissue	59	−1.44	−1.93 to −0.95	97.08	random

CI, confidence interval.