Objective: To establish a new model for analyzing the correlation between the terminal restriction fragment (TRF) length and telomerase activity in non-small cell lung cancer (NSCLC) patients due to inconsistent results in previous reports.
Methods: Between January 1999 and December 1999, 79 NSCLC patients were studied. The activity of telomerase was measured by telomeric repeat amplification protocol, and the telomere restriction fragment (TRF) length was measured by Telomere Length Assay Kit and Southern blotting. The correlation between expression of telomerase activity and the TRF length ratio (TRFLR) using the tumor-to-normal TRFLR (t/n TRFLR) was examined.
Results: Positive telomerase activity was observed in 48 (60.8%) of the tumor tissue samples and in 5 (6.3%) of the normal tissue samples (P < 0.0001). The mean TRF lengths were 5.32+/-1.53 kb in normal tissue samples and 3.95+/-1.92 kb in tumor tissue samples, respectively (P = 0.0001). The 4-year cumulative survival rates of lower t/n TRFLR (< or = 75%) and higher t/n TRFLR (>75%) patients were 69.2 and 41.2%, respectively (P = 0.0227). Independent prognostic factors include t/n TRFLR (P = 0.014), T-status (P = 0.027), and N-status (P = 0.020) of the tumor.
Conclusions: Our data suggest that there is a good correlation between the t/n TRFLR and expression of telomerase activity. A higher t/n TRFLR may indicate that the tumor regains its ability to repair the telomere lost and escapes the apoptosis scenario, which is subsequently reflected in poorer patient outcomes.