Table 1. Basic characteristics of the included 25 studies.
| Authors | Country | Patient criteria | Document type | NOS | Group | No. | Age | Gender | Tumor location | pTNM stage | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Male | Female | Upper | Middle | Lower | I | II | III | IV | ||||||||||
| Song et al. (4) | China | GC underwent surgery (2007–2011) | Retrospective Study | 7 | YG ≤40 | 112 | – | 59 | 53 | 12 | 21 | 64 | 5 | 30 | 59 | 18 | ||
| OG ≥70 | 358 | – | 274 | 84 | 61 | 64 | 208 | 25 | 89 | 206 | 38 | |||||||
| Cormedi et al. (5) | Brazil | GC (2011–2013) | Retrospective Study | 8 | YG ≤40 | 71 | 37 | 34 | 37 | – | – | – | 4 | 5 | 23 | 36 | ||
| OG >40 | 223 | 63.74 | 135 | 88 | – | – | – | 35 | 29 | 52 | 89 | |||||||
| Tavares et al. (8) | Portugal | GC with surgery (2000–2005) | Retrospective Study | 7 | YG ≤40 | 23 | – | 12 | 11 | – | – | – | 6 | 6 | 4 | 6 | ||
| OG >40 | 360 | – | 207 | 153 | – | – | – | 76 | 43 | 105 | 97 | |||||||
| Guan et al. (9) | the United States | GC (1973–2014) | Retrospective Study | 8 | YG <35 | 1,369 | – | 728 | 641 | 338 | 133 | 275 | 51 | 59 | 119 | 385 | ||
| OG ≥65 | 46,521 | – | 28,104 | 18,417 | 11,839 | 3,617 | 12,243 | 3,838 | 3,407 | 3,604 | 4,358 | |||||||
| Isobe et al. (10) | Japan | GAC (1977–2006) | Retrospective Study | 8 | YG ≤40 | 169 | 34.5±4.8 | 79 | 90 | 34 | 70 | 40 | 68 | 30 | 23 | 48 | ||
| OG >40 | 3,649 | 64.5±10.0 | 2,518 | 1,131 | 790 | 1,047 | 1,341 | 1,765 | 471 | 628 | 782 | |||||||
| Kim et al. (11) | Korea | GC (1986–2000) | Retrospective Study | 8 | YG ≤35 | 137 | 30.6±5.1 | 63 | 74 | 23 | 50 | 56 | 41 | 21 | 36 | 39 | ||
| OG >70 | 194 | 73.3±3.1 | 131 | 63 | 16 | 41 | 130 | 60 | 41 | 55 | 38 | |||||||
| Kunisaki et al. (12) | Japan | GC underwent curative surgery (1985–1999) | Retrospective Study | 8 | YG ≤40 | 131 | 35.2±5.0 | 64 | 67 | 44 | 65 | 19 | 79 | 16 | 24 | 12 | ||
| OG ≥55 | 918 | 60.2±3.2 | 658 | 260 | 340 | 386 | 168 | 510 | 123 | 174 | 111 | |||||||
| Liu et al. (13) | China | GC underwent surgery; no chemotherapy; no metastasis. (2008–2014) | Retrospective Study | 7 | YG ≤40 | 198 | – | 115 | 83 | – | – | – | – | – | – | – | ||
| OG ≥55 | 1,096 | – | 895 | 201 | – | – | – | – | – | – | – | |||||||
| Okamoto et al. (14) | Japan | GC underwent laparotomy (1960–1984) |
Retrospective Study | 6 | YG <30 | 34 | 24.9 | 10 | 24 | 3 | 13 | 7 | – | – | – | – | ||
| OG ≥75 | 132 | 77.9 | 97 | 35 | 12 | 37 | 66 | 39 | 7 | 31 | 55 | |||||||
| Takatsu et al. (15) | Japan | GC underwent surgical resection (2000–2010) | Retrospective Study | 8 | YG ≤40 | 136 | 36 [16–39] | 72 | 64 | 25 | 70 | 35 | 65 | 21 | 28 | 22 | ||
| OG ≥60 | 1,435 | 65 [60–69] | 1,024 | 411 | 385 | 581 | 416 | 786 | 206 | 253 | 190 | |||||||
| Tekesin et al. (16) | Turkey | GC (1990–2014) | Retrospective Cohort Study | 7 | YG ≤40 | 92 | 36 [22–40] | 53 | 39 | 17 | – | – | 5 | 4 | 17 | 52 | ||
| OG >40 | 774 | 60 [41–75] | 553 | 221 | 141 | – | –– | 25 | 46 | 195 | 372 | |||||||
| Wang et al. (17) | China | GC underwent gastrectomy (1998–2006) | Prospective Study | 7 | YG ≤40 | 21 | 34.9±1.1 | 9 | 12 | 1 | 7 | 13 | – | – | – | – | ||
| OG >55 | 36 | 67.1±0.8 | 22 | 14 | 4 | 7 | 25 | 11 | 9 | 15 | 1 | |||||||
| Hsieh et al. (18) | Japan | GAC underwent curative gastrectomy (1981–1992) | Retrospective Study | 7 | YG ≤40 | 115 | – | 46 | 69 | 14 | 27 | 68 | 23 | 22 | 56 | 14 | ||
| OG >60 | 1,009 | – | 626 | 373 | 194 | 160 | 626 | 293 | 160 | 467 | 89 | |||||||
| Ma et al. (19) | China | GC underwent curative surgery (2009–2011) | Retrospective Study | 7 | YG ≤40 | 125 | – | 76 | 49 | – | – | – | 30 | 24 | 71 | – | ||
| OG >40 | 1,752 | – | 1,341 | 411 | – | – | – | 403 | 400 | 946 | – | |||||||
| Mitsudomi et al. (20) | Japan | GC (1970–1984) | Retrospective Study | 7 | YG <40 | 128 | – | 66 | 62 | 13 | 58 | 31 | – | – | – | – | ||
| OG ≥50 | 1,275 | – | 863 | 412 | 131 | 379 | 550 | – | – | – | – | |||||||
| Kulig et al. (21) | Poland | GC (1977–1998) | Retrospective Study | 6 | YG ≤40 | 214 | 35.0 | 119 | 95 | 24 | 56 | 56 | 24 | 14 | 25 | 63 | ||
| OG >40 | 3,217 | 61.0 | 2,277 | 940 | 387 | 733 | 677 | 315 | 251 | 380 | 770 | |||||||
| Bani-Hani et al. (22) | Jordan | GAC (1991–2001) | Retrospective Study | 7 | YG ≤40 | 17 | 36.3±0.9 | 7 | 10 | 5 | 3 | 3 | 4 | 2 | 4 | 7 | ||
| OG >40 | 159 | 63.8±0.7 | 104 | 55 | 26 | 39 | 83 | 11 | 39 | 55 | 46 | |||||||
| Kim et al. (23) | Korea | GC underwent surgery (1993–2000) | Retrospective Study | 7 | YG ≤40 | 175 | 34.58±4.26 | 100 | 75 | 19 | 67 | 83 | 79 | 20 | 49 | 37 | ||
| OG >40 | 1,124 | 59.25±9.17 | 765 | 359 | 120 | 364 | 624 | 439 | 145 | 304 | 236 | |||||||
| Lai et al. (24) | Korea | GC underwent curative surgery (1987–2004) | Retrospective Study | 8 | YG ≤40 | 883 | 35 | 476 | 407 | 125 | – | – | 444 | 135 | 213 | 91 | ||
| OG >40 | 6,071 | 58.7 | 4,195 | 1,876 | 720 | – | – | 2,850 | 1,057 | 1,567 | 597 | |||||||
| Maehara et al. (25) | Japan | GC underwent surgery (1965–1991) | Retrospective Study | 6 | YG <40 | 174 | 38.8±4.9 | 89 | 85 | 31 | 58 | 63 | – | – | – | – | ||
| OG >70 | 356 | 74.8±3.9 | 247 | 109 | 90 | 86 | 152 | – | – | – | – | |||||||
| Silva et al. (26) | Brazil | GAC (1988–2005) | Retrospective Study | 7 | YG ≤40 | 62 | – | 38 | 24 | 9 | – | 50 | 21 | – | 35 | – | ||
| OG >40 | 453 | – | 288 | 165 | 68 | – | 385 | 127 | – | 280 | – | |||||||
| Zhou et al. (27) | China | GC resections (2004–2014) | Retrospective Study | 7 | YG ≤40 | 152 | 33.7±5.54 | 53 | 99 | 8 | 57 | 75 | 39 | 32 | 66 | 15 | ||
| OG >40 | 250 | 62.9±10.4 | 178 | 72 | 75 | 53 | 115 | 141 | 35 | 52 | 22 | |||||||
| Adachi et al. (28) | Japan | GC underwent surgery (1981–1990) | Retrospective Study | 7 | YG <40 | 36 | – | 20 | 16 | – | – | 6 | 16 | 5 | 8 | 7 | ||
| OG >60 | 68 | – | 43 | 25 | – | – | 27 | 25 | 13 | 16 | 14 | |||||||
| Bautista et al. (29) | the United States | Non-cardia GAC (2000–2010) | Retrospective Cohort Study | 8 | YG <40 | 46 | 34.1±4.1 | 24 | 22 | 1 | 10 | 14 | – | – | – | – | ||
| OG ≥50 | 1,208 | 71.5±3.8 | 714 | 494 | 65 | 379 | 426 | – | – | – | – | |||||||
| Wang et al. (30) | China | GC underwent curative gastrectomy (2005–2010) | Retrospective Study | 8 | YG ≤40 | 342 | 34.1±5.2 | 198 | 144 | 53 | 79 | 177 | 82 | 97 | 137 | 26 | ||
| OG >40 | 3,588 | 61.4±10.1 | 2,448 | 1,140 | 841 | 741 | 1,783 | 876 | 927 | 1,522 | 263 | |||||||
No., number of patients; pTNM, pathological (p), primary tumor (T), lymph nodes (N) and distant metastases (M); GC, gastric cancer; GAC, gastric adenocarcinoma.