Characteristics of studies included in the systematic review and meta-analysis
| Author | Year | Region | Sample type | Telomere measurement metric | Measurement method | Patients (n) | Telomere length | Follow-up (years) | Cut-off value | Outcomes (HR, 95% CI, P-value) | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Short (n) | Long (n) | ||||||||||
| Duggan et al. [17] | 2014 | America | Blood plasma | Relative telomere length [telomere-to-single copy gene ratio (T/S ratio)] | qPCR | 611 | 306 | 305 | 11.2 years | Median (0.81) | OS: 1.33 (0.90–2.00, P = 0.14) |
| DSS: 1.33 (0.79–2.27, P = 0.27) | |||||||||||
| Fordyce et al. [18] | 2006 | America | Tumor tissue | Telomere DNA content (TC) | Slot blot assay | 77 | 35 | 25 | 23 years | Tertiles (short < 101%, long > 123%) | DFS: 4.39 (1.47–13.08, P = 0.008) |
| Gay-Bellile et al. [19] | 2016 | Europe | Tumor tissue | Relative telomere length (T/S ratio) | qPCR | 55 | 22 | 23 | 17 years | Median (1.03) | OS: 2.9 (1.00–8.47, P = 0.050) |
| DFS: 3.31 (1.38–7.04, P = 0. 0076) | |||||||||||
| Heaphy et al. [20] | 2007 | America | Tumor tissue | TC | Slot blot assay | 530 | 444 | 86 | 9.16 years | Threshold (short ≤ 200%, long > 200%) | OS: 2.25 (1.09–4.64, P = 0.029) |
| DFS: 3.14 (1.27–7.76, P = 0.013) | |||||||||||
| Lu et al. [21] | 2011 | Europe | Tumor tissue | Relative telomere length (T/S ratio) | qPCR | 348 | 170 | 166 | 9 years | Median | OS: 1.27 (0.76–2.13) |
| DFS: 1.19 (0.76–1.82) | |||||||||||
| Shen et al. [23] | 2012 | America | Blood plasma | Relative telomere length (T/S ratio) | qPCR | 1,026 | 510 | 516 | 9.4 years | Median (0.73) | OS: 0.91 (0.68–1.20) |
| DSS: 0.99 (0.68–1.45) | |||||||||||
| Simpson et al. [22] | 2015 | Europe | Tumor tissue | Telomere length (in kb) | Single telomere length analysis (STELA) assay | 120 | 8 | 112 | 4.6 years | Median (2.26 kb) | OS: 21.4 (7.9–57.6, P < 0.0001) |
| Svenson et al. [24] | 2008 | Europe | Blood plasma | Relative telomere length (T/S ratio) | qPCR | 227 | 114 | 113 | N/A | Median (0.73) | OS: 0.34 (0.16–0.75, P = 0.007) |
| Vodenkova et al. [25] | 2020 | Europe | Blood plasma | Relative telomere length (T/S ratio) | qPCR | 151 | N/A | N/A | N/A | Median | OS: 1.02 (0.34–3.05, P = 0.97) |
| RFS: 0.72 (0.29–1.77, P = 0.47) | |||||||||||
OS: overall survival; DSS: disease-specific survival; DFS: disease-free survival; RFS: recurrence-free survival; qPCR: quantitative polymerase chain reaction; HR: hazard ratio; CI: confidence intervals; N/A: not available