Table 3.
Telomerase as a marker of disease in colorectal cancer
| Ref. | Cases | Main findings |
| Engelhardt et al[32], 1997 | 80 (50 CRCs, 20 polyps, 10 colitis) cancerous and 50 CRC patient-matched non-cancerous mucosa specimens | Telomerase activity |
| Absent in normal tissues | ||
| Higher in CRCs than in nonneoplastic lesions | ||
| Higher in late-stage than in early-stage tumours | ||
| Tatsumoto et al[58], 2000 | 100 CRC and patient-matched non-cancerous mucosa specimens | Telomerase activity |
| Higher in CRC than in adjacent non-cancerous mucosa | ||
| Detectable in adjacent non-cancerous mucosa derived from intestinal crypt basal cells | ||
| Not correlated with CRC stage or grade | ||
| Has prognostic value for OS and DFS (high telomerase activity: poor prognosis) | ||
| Niiyama et al[59], 2001 | 140 CRC and patient-matched non-cancerous mucosa specimens; 20 adenomas | TERT mRNA and telomerase activity |
| Higher in CRCs than in adenomas | ||
| Higher in adenomas than in normal mucosa | ||
| Naito et al[60], 2001 | 66 (50 adenomas, 6 mucosal carcinomas, 10 invasive carcinomas) specimens | Positive correlation between TERT mRNA and telomerase activity |
| TERT levels increase with adenoma-carcinoma sequence | ||
| Gertler et al[61], 2002 | 57 CRC and patient-matched non-cancerous mucosa specimens | Both CRC and adjacent non-cancerous mucosa are positive for TERT |
| TERT levels lower in tumours than in non-cancerous mucosa in most cases | ||
| TERT levels not correlated with tumour stage | ||
| TERT has prognostic value for OD and DFS (high telomerase activity: poor prognosis) | ||
| Kawanishi-Tabata et al[62], 2002 | 122 CRCs, stage II(52 colon, 70 rectum) | 80% of CRC are telomerase-positive |
| Higher percentage of telomerase-positive tumours in the colon than in the rectum | ||
| High telomerase activity: Good prognosis | ||
| Ghori et al[63], 2002 | 30 CRCs and 20 patient-matched non-cancerous mucosa specimens | Telomerase activity |
| Higher in CRCs than in adjacent non-cancerous mucosa | ||
| Correlated with Duke's stage | ||
| Boldrini et al[64], 2002 | 36 CRC and patient-matched non-cancerous mucosa specimens, 8 adenomatous polyps, 9 dysplastic polyps | Telomerase activity |
| Absent in normal mucosa and adenomas | ||
| Higher in CRCs than in dysplastic polyps | ||
| Higher in late-stage than in early-stage tumours | ||
| Maláska et al[65], 2004 | 41 CRC and patient-matched non-cancerous mucosa specimens | Telomerase activity |
| Present in 83% of CRCs | ||
| Absent or at very low level in normal mucosa | ||
| Higher in metastatic tumours | ||
| Boldrini et al[66], 2004 | 43 CRCs | TERT levels and telomerase activity higher in tumours with mutated TP53 |
| Sanz-Casla et al[67], 2005 | 103 CRCs | Telomerase activity increases with tumour progression (Duke's stage) |
| Higher percentage of telomerase-positive tumours in the colon than in the rectum | ||
| Telomerase activity has prognostic value for DFS (high telomerase activity: poor prognosis) | ||
| Garcia-Aranda et al[38], 2006 | 91 CRC and patient-matched non-cancerous mucosa specimens | Telomerase activity |
| Present in 81% of CRCs | ||
| Present at very low levels in 15% of normal samples | ||
| Not correlated with tumour progression | ||
| No prognostic value | ||
| Vidaurreta et al[68], 2007 | 97 CRCs | Telomerase activity |
| Present both in MSI and MSS tumours | ||
| Has prognostic value for OS (high telomere activity: poor prognosis) | ||
| Bautista et al[69], 2007 | 108 rectal cancer and patient-matched non-cancerous mucosa specimens | Telomerase activity |
| Higher in rectal cancer than in normal mucosa | ||
| Not correlated with tumour stage and grade | ||
| Has prognostic value for DFS and OS | ||
| Terrin et al[55], 2008 | 85 CRC and 42 patient-matched non-cancerous mucosa specimens, 49 plasma samples | TERT levels |
| Higher in CRCs than in adjacent non-cancerous mucosa | ||
| Increase with tumour stage and grade | ||
| Not correlated with MSI status | ||
| Not correlated with tumour location | ||
| Plasma TERT levels correlated with tumour TERT levels | ||
| Valls Bautista et al[70], 2009 | 6 cases, each with cancer, polyps and normal mucosa; 8 polyps and normal mucosa | Telomerase activity |
| Increases with adenoma-carcinoma sequence | ||
| Kojima et al[71], 2011 | 106 CRC and paired adjacent non-cancerous mucosa specimens | Elongation of the 3’OH of telomere by telomerase may increase Malignant potential of cancer cells |
| Telomerase activity has prognostic values for OS (telomeraseactivated without 3'OH shortened telomeres: poor prognosis) | ||
| Safont et al[72], 2011 | 48 CRC and adjacent non-cancerous mucosa specimens and 48 plasma samples | Plasma TERT levels correlated with tumour TERT levels |
| Higher circulating TERT levels in stage IV tumours | ||
| No correlation between telomerase expression and prognosis | ||
| Bertorelle et al[73], 2013 | 137 CRCs | TERT levels: |
| Increase with tumour stage and grade | ||
| Not correlated with MSI status | ||
| Not correlated with tumour location | ||
| Have prognostic value for OS and for both OS and DFS for stage II patients (high TERT levels: poor prognosis) |
CRC: Colorectal cancer; DFS: Disease free survival; OS: Overall survival; TERT: Telomerase reverse transcriptase; MSI: Microsatellite instability.