Telomerase activity of blood samples and recurrence of colorectal cancer

Recurrence, which occurs in about 20-30% of colorectal cancer patients after curative surgical treatment, is an important factor in determining prognosis. Therefore, early detection and prediction of recurrence is an important issue in the treatment of the disease. Telomerase is a reverse transcriptase that synthesizes telomere DNA, thereby compensating for telomere loss that occurs with each replication cycle, and limits proliferation cells. Telomerase is expressed in the majority of primary human tumors and hTERT is considered one of the most important proteins affecting telomerase activity. We evaluated telomerase activity in mesenteric and peripheral blood samples in addition to hTERT expression in cancerous tissues by means of immunohistochemistry in 120 patients who underwent curative surgical treatment at our department.

We investigated the factors correlated with recurrence.

In univariate analysis, we found recurrence was significantly correlated with positive telomerase activity in the mesenteric vein (p=0.0021), positive telomerase activity in the peripheral vein (p=0.0032), histological type except well differentiated adenocarcinoma (p=0.0013), lymphatic infiltration (p=0.044), lymph node metastasis at surgery (p<0.0001), positive CEA (p=0.0004) and negative TERT immunoreactivity (p=0.012). In multivariate analysis, we found lymph node involvement at surgery (p=0.0045, hazard ratio: 6.21) and positive telomerase activity in peripheral vein (p=0.037, hazard ratio: 3.13) were significantly associated with the existence of recurrence.

Our results show that measuring telomerase activity in peripheral blood samples is effective in predicting future recurrence to a degree greater than macroscopically examined tumor depth or other clinicopathological parameters.