Table 1. Characteristics of included studies.
| Author | Year | Country | Age(y) | Case | Control | Method | Case type | Control type | ||
|---|---|---|---|---|---|---|---|---|---|---|
| M | U | M | U | |||||||
| Bammidi LS | 2012 | India | 20–75 | 28 | 22 | 18 | 32 | BSP | tissues | blood |
| Bhagat R | 2014 | India | 20–79 | 58 | 76 | 11 | 30 | MSP | tissues | tissues |
| Li M | 2006 | China | NA | 6 | 12 | 0 | 10 | MSP | tissues | tissues |
| Liu Z | 2005 | USA | 27–81 | 13 | 39 | 15 | 25 | MSP | tissues | tissues |
| Makarla P | 2005 | USA | 51.5(20–86) | 7 | 16 | 3 | 36 | MSP | tissues | tissues |
| Niederacher D | 1999 | Germany | NA | 6 | 17 | 0 | 10 | MSP | tissues | tissues |
| Shih YC | 1997 | Australia | NA | 0 | 45 | 0 | 2 | MSP | tissues | tissues |
| Tam KF | 2007 | China | 53.1±1.4 | 17 | 72 | 5 | 30 | MSP | tissues | tissues |
| Wong YF | 1999 | China | NA | 2 | 47 | 0 | 10 | MSP | tissues | blood |
| Shen W | 2008 | China | 52.2, 53.2 | 13 | 50 | 0 | 30 | BSP | tissues | tissues |
| Wei W | 1999 | China | 46.5±12.47 | 5 | 21 | 0 | 2 | BSP | tissues | tissues |
| Xu B | 2003 | China | NA | 4 | 36 | 0 | 20 | MSP | tissues | tissues |
Blood: peripheral blood samples from each patient with ovarian cancer; tissues: benign ovarian tissues, normal ovarian tissues of cancer-free patients and adjacent tissues; MSP: methylation-specific polymerase chain reaction; BSP: bisulfite sequencing PCR; NA: not available; M: methylation; U: unmethylation.