Table 1. Major features of the included studies.
| Study | Location | Number | Age (mean) | Cancer Type | Follow-up (months) | Materials | Detection Method | Measurement | Hypomethylation Cut-off | Rate (%) | Quality Score |
| JM Bae 2011 | Korea | 198 | 59 | GC | 46(1–72) | tumor tissue | Pyrosequencing | LINE-1 | dichotomy | 55.79 | 17 |
| Alu | dichotomy | 17.37 | |||||||||
| ZZ Zhu 2011 | USA | 722 | 72 | all cancers | 85(2–118) | blood | Pyrosequencing | LINE-1 | dichotomy | 68.1 | 17 |
| Alu | dichotomy | 26.0 | |||||||||
| F Ohka 2011 | Japan | 54 | 59 | GBM | 172.8(8.9–336.8) | tumor tissue | Pyrosequencing | LINE-1 | dichotomy | 63.5 | 15 |
| F Ohka 2011 | Japan | 57 | 42 | LGG | 172.8(8.9–336.8) | tumor tissue | Pyrosequencing | LINE-1 | dichotomy | 68.9 | 15 |
| H Shigaki 2012 | Japan | 203 | 70 | GC | 34.8(13.6–56) | tumor tissue | Pyrosequencing | LINE-1 | dichotomy | 72.3 | 17 |
| Y Aoki 2012 | Japan | 81 | 67.5 | MM | 20(3–40) | bone marrow | BSP | LINE-1 | dichotomy | 41.7 | 14 |
| Alu | dichotomy | 37.1 | |||||||||
| Sat-alphaα | dichotomy | 39.8 | |||||||||
| S Hoshimoto 2012 | USA | 126 | 63.4 | Melanoma | 70(3–140) | tumor tissue | MSP | LINE-1 | dichotomy | 32 | 15 |
| L Sigalotti 2011 | Italy | 42 | 54 | Melanoma | 15.3(11.0–31.5) | tissue-cell culture | Pyrosequencing | LINE-1 | dichotomy | 31.13 | 16 |
| K Saito 2010 | Japan | 379 | 48 | NSCLC | 45.5(2-149) | tumor tissue | BSP | LINE-1 | dichotomy | 81 | 18 |
| S Fabris 2011 | Italy | 81 | 65 | CLK | 24(12-120) | blood | Pyrosequencing | Alu | dichotomy | 21.4 | 15 |
| Sat-alphaα | dichotomy | 84.0 | |||||||||
| K Nosho 2009 | USA | 2068 | 65.6 | CRC | 144(24–312) | tumor tissue | Pyrosequencing | LINE-1 | dichotomy | 61.50 | 18 |
| CS Zhang 2011 | China | 95 | 49.86 | HCC | 25(0–50) | tumor tissue | Q-MSP | LINE-1 | dichotomy | 75.5 | 16 |
| YY Rhee 2012 | Korea | 207 | 55 | CRC | 46(1–76) | tumor tissue | Pyrosequencing | LINE-1 | dichotomy | 53 | 20 |
| Alu | dichotomy | 18.60 | |||||||||
| J PATTAMADILOK 2008 | Thailand | 59 | 50 | OC | 59(0–108) | tumor tissue | COBRA | LINE-1 | dichotomy | 34.87 | 17 |
| A Murata 2013 | Japan | 74 | 65 | CRC | 46.8(50.4–144) | tumor tissue | Pyrosequencing | LINE-1 | dichotomy | 52.80 | 18 |
| S Iwagami 2013 | Japan | 217 | 65.9 | ESCC | 31.2(3–66) | tumor tissue | Pyrosequencing | LINE-1 | quatile | 65.10 | 19 |
| CS Furniss 2008 | USA | 193 | 59 | HNSCC | 36(0–60) | tumor tissue | COBRA | LINE-1 | dichotomy | 45 | 15 |
| Z Xv 2010 | China | 105 | 50 | HCC | 20(0–40) | tumor tissue | MSP | LINE-1 | dichotomy | 74.65 | 16 |
| Annek Q 2012 | USA | 243 | 55 | BC | 7.5(0–15) | tumor tissue | AQAMA | LINE-1 | quatile | 18.5 | 16 |
| S Ogino2008 | USA | 243 | NA | CRC | 60(0–120) | tumor tissue | Pyrosequencing | LINE-1 | quatile | 45 | 17 |
Abbreviations: MSP = Methylation-specific PCR; Q-MSP = Quantitive MSP; BSP = bisulfite sequencing PCR; COBRA = Combined bisulfite restriction analysis ; GC = Gastric Cancer;; GBMs = Glioblastoma Multiformes; LGG = Glioblastoma Glioblastoma multiformes; MM = Multiple Myeloma; NSCLC = Non-Small Cell Lung Cancer; CRC = Colorectal cancer; HCC = Hepatocellular Carcinoma; HNSCC = Head and Neck Squamous Cell Carcinomas; CLL = chronic lymphocytic leukemia; ESCC = Esophageal Squamous Cell Carcinoma; OC = Ovarian Cancer; BC = Breast Cancer; CLK = chronic lymphocytic leukemia.