Table 1. Characteristics of included studies.
| Cancer Types | Author | Year | Patients' Number | Rate of High EZH2 Expression | Test Method | Definition of High Expression |
|---|---|---|---|---|---|---|
| Breast cancer | Kleer | 2003 | 280 | 40.71% | IHC+qRT-PCR | 3-4 score ( 4-value intensity score) defined high expression |
| Collett | 2006 | 190 | 47.37% | IHC | staining index (values 0-9) >3* | |
| Pietersen | 2008 | 295 | 40.34% | IHC | NC | |
| Athanassiadou | 2011 | 100 | 64.00% | IHC | >10% of nuclear staining | |
| Gong | 2011 | 88 | 63.64% | IHC | >10% of nuclear staining | |
| Reijm | 2011 | 278 | 66.55% | IHC+qRT-PCR | NC | |
| Alford | 2012 | 480 | 42.50% | IHC | >25% of nuclei staining | |
| Brot | 2012 | 140 | 85.71% | IHC | >25% of nuclei staining | |
| Hussein | 2012 | 261 | 33.33% | IHC | nuclear staining was scored based on intensity (0-3) and ≥2 defined high expression | |
| Jene-Sanz | 2013 | 95 | 43.16% | IHC+qRT-PCR | NC | |
| Knudsen | 2013 | 236 | 71.61% | IHC | >15% of nuclear staining | |
| Panousis | 2013 | 105 | 57.14% | IHC | >10% of nuclei staining | |
| Roh | 2013 | 49 | 67.35% | IHC | >25% of nuclei staining | |
| Bae | 2014 | 146 | 49.32% | IHC | >30% of nucleai staining | |
| Dong | 2014 | 410 | 24.15% | IHC | staining index (values 0-9) >3* | |
| Reijm | 2014 | 250 | 46.40% | IHC | 1 | |
| Lung cancer | Kikuchi | 2010 | 154 | 62.34% | IHC | >25% of nuclei staining |
| Takawa | 2011 | 292 | 46.23% | IHC+qRT-PCR | NC | |
| Cao | 2012 | 94 | 62.77% | RT-PCR | A fold difference >1 is considered high EZH2 expression | |
| Huqun | 2012 | 106 | 62.26% | IHC | >50% of nuclei stained | |
| Lv | 2012 | 69 | 63.77% | IHC+qRT-PCR | >25% of nuclei staining | |
| Behrens | 2013 | 541 | 26.80% | IHC | final score (values 0-300) >125** | |
| Chen | 2013 | 42 | 42.86% | IHC | final IHC score (values 0-12) >3*** | |
| Wan | 2013 | 113 | 50.44% | IHC | NC | |
| Xu | 2014 | 360 | 56.67% | IHC | staining index (values 0-9) >3* | |
| Geng | 2015 | 195 | 49.23% | IHC | ≥30% of tumor cells with strong staining intensity=2 | |
| Colorectal cancer | Mimori | 2005 | 61 | 52.46% | qRT-PCR | > the median tumor/normal ratio |
| Fluge | 2009 | 241 | 17.01% | IHC | staining index (values 0-9) >3* | |
| Wang | 2010 | 119 | 69.75% | IHC | >30% of nucleai staining | |
| Takawa | 2011 | 172 | 91.86% | IHC | NC | |
| Benard | 2014 | 247 | 23.89% | IHC+qRT-PCR | > median percentage of positively stained nuclei in the marked area | |
| Meng | 2014 | 112 | 52.68% | IHC | >50% of nucleai staining | |
| Liu | 2015 | 82 | 80.49% | qRT-PCR | > the median tumour/normal ratio | |
| Bladder cancer | Raman | 2005 | 24 | 87.50% | IHC | staining index (values 0-9) >3* |
| Hinz | 2008 | 99 | 90.91% | qRT-PCR | > median expression levels | |
| Prostate cancer | Bachmann | 2006 | 104 | 8.65% | IHC | staining index (values 0-9) >3* |
| Li | 2011 | 129 | 44.96% | IHC | staining index (values 0-9) >3* | |
| Renal cancer | Hinz | 2013 | 101 | 56.44% | IHC+qRT-PCR | > median expression levels |
| Wagener | 2009 | 411 | 11.19% | IHC | >25% of nucleai staining | |
| Liu | 2010 | 373 | 52.82% | IHC | final IHC score (values 0-12) ≥2*** | |
| Glioblastoma | Wu | 2013 | 128 | 62.50% | IHC | staining index (values 0-9) >4.5* |
| Zhang | 2013 | 83 | 51.81% | IHC | ≥2 (scored 0 to 3) indicated high expression | |
| Digestive cancer | He | 2015 | 98 | 54.08% | IHC | >50% of nucleai staining |
| Liu | 2010 | 108 | 53.70% | IHC | >25% of nuclei staining | |
| Ha | 2011 | 164 | 52.44% | IHC | final IHC score (values 0-12) ≥10*** | |
| He | 2012 | 117 | 70.09% | IHC | >50% of nucleai staining | |
| Lee | 2012 | 178 | 92.13% | IHC | staining index (values 0-9) >median score* | |
| Li | 2012 | 84 | 64.29% | IHC | final IHC score (values 0-12) ≥4*** | |
| Zhang | 2013 | 167 | 76.05% | IHC | staining index (values 0-9) >3* | |
| Gynecological cancer | Bachmann | 2006 | 276 | 17.75% | IHC | staining index (values 0-9) >3* |
| Rao | 2010 | 179 | 49.72% | IHC | >50% of nucleai staining | |
| Liu | 2014 | 101 | 68.32% | IHC | staining index (values 0-9) ≥4* | |
| Head and neck cancer | Cao | 2014 | 117 | 50.43% | IHC | cutoff value was set as the median of the labeling index |
*
staining index (values 0-9) = staining intensity (0-3) × proportion of immunopositive cells (<10% = 1, 10-50% = 2, >50% = 3).
**
The final score was then obtained by multiplying the intensity and extension values (range, 0-300) by using a 4-value intensity score (0, 1, 2, and 3) and the percentage (0-100%) of the extent of reactivity in each core.
***
the number of positive cancerous cells was estimated as follows (0, no positive cells; 1, 0-25% positive cells; 2, 25-50% positive cells; 3, 50-75% positive cells; and 4, 75-100% positive cells). These scores were multiplied with an intensity scale (0, negative; 1, weak; 2, moderate; and 3, intensive), and the final score ranged from 0-12; NC: not clear.