Table 1. Main characteristics of studies included in meta-analysis.
| First author | Year of publication | Time frame | Race or country | No. of subjects (male/female) | Median age [range age] | Regional or distant metastasis | Synchronous or metachronous metastasis | Type of sampling | Techniques to test HER2 status |
|---|---|---|---|---|---|---|---|---|---|
| Chariyalertsak S | 1994 | 1990-1991 | Thailand | 97 (NR) | NR [NR] | Regional | Synchronous | Surgery or biopsy | IHC |
| Kim JS | 1997 | 1992-1993 | Korea | 45 (NR) | NR [NR] | Regional | Synchronous | Surgery | Southern blot |
| Kim JH | 2009 | 1995-2003 | Korea | 222 (NR) | 55.4 [NR] | Regional | Synchronous | Surgery | IHC |
| Marx AH | 2009 | NR | Germany | 51 (NR) | NR | Regional | Synchronous | Surgery | IHC and FISH |
| Kim JY | 2010 | NR | Caucasian | 193 (NR) | NR [NR] | Regional | Synchronous | Surgery | IHC and FISH |
| Kim MA | 2011 | 1990-2006 | Korea | 250 (NR) | NR | Regional and distant | Synchronous or metachronous | Surgery or biopsy | IHC and FISH |
| Geng YT | 2011 | 2003-2005 | China | 110 (79/31) | 63.5 [28-85] | Regional | Synchronous | Surgery | IHC |
| Bozzetti C | 2011 | NR | Italy | 39 (NR) | NR [40-88] | Regional or distant | Synchronous and metachronous | Surgery or biopsy | IHC and FISH |
| Zhang YL | 2012 | 2010-2011 | China | 112 (NR) | 59 [30-79] | Regional | Synchronous | Surgery | IHC and FISH |
| Tsapralis D | 2012 | 2004-2007 | Athens | 45 (NR) | NR [NR] | Regional | Synchronous | Surgery | IHC and CISH |
| Fassan M | 2012 | 2000-2003 | Italy | 47 (38/9) | 67.9 [49-87] | Regional | Synchronous | Surgery | IHC and CISH |
| Asioli S | 2012 | NR | Italy | 60 (NR) | NR [NR] | Regional or distant | Synchronous | Surgery | IHC |
| Shinozaki E | 2013 | NR | Caucasian | 58 (45/13) | NR [NR] | Distant | Synchronous and metachronous | Surgery | IHC |
| Pagni F | 2013 | 2008-2011 | Italy | 34 (16/18) | 68.5 [NR] | Regional or distant | Synchronous | Surgery and biopsy | IHC and FISH |
| Kochi M | 2013 | 1990-2010 | Japan | 102 (82/20) | 68 [29-86] | Regional | Synchronous | Surgery | IHC and FISH |
| Fusco N | 2013 | 1996-2008 | Italy | 154 (NR) | NR [NR] | Regional | Synchronous | Surgery | IHC |
| Cho EY | 2013 | 2000-2004 | Korea | 138 (NR) | NR [NR] | Distant | Synchronous and metachronous | Surgery | IHC and SISH |
| Geng Y | 2014 | 2003-2005 | China | 110 (79/31) | 63.5 [28-85] | Regional | Synchronous | Surgery | IHC |
HER2, human epidermal growth factor receptor 2; NR, not reported; IHC, immunohistochemistry; FISH, fluorescence in situ hybridization; CISH, chromogenic in situ hybridization; SISH, silver in situ hybridization.