Circulating DNA is a useful prognostic factor in patients with advanced non-small cell lung cancer

Background: Circulating DNA is observed at higher concentrations in patients with lung cancer than in controls. Qualitative and quantitative analysis of circulating DNA is a promising noninvasive tool. Our aim was to prospectively study the association between the catalytic subunit of telomerase (human telomerase reverse transcriptase [ hTERT ]) in plasma and clinical variables and survival in a large-scale non-small cell lung cancer (NSCLC) study. Methods: Four hundred forty-six patients with stages IIIB and IV NSCLC with a median follow-up of 9.7 months (range, 0.5–45) were analyzed. Blood samples were collected before therapy start (cisplatin/docetaxel). Quantification of baseline circulating DNA was determined as the amount of free hTERT in plasma, by using real-time quantitative polymerase chain reaction. Results: Patients with hTERT ≤49.8 ng/ml (median value) had a median time to progression (TTP) of 6.3 months compared with 4.9 for hTERT more than 49.8 ng/ml ( p = 0.001). Overall survival (OS) was significantly higher (10.9 versus 9.3 months) at lower hTERT levels ( p = 0.012). When calculations were done using hTERT as continuous variable, we did not observe independent significant differences. Thus, there is an apparent discrepancy in p values when hTERT is considered as a continuous versus dichotomized variable. There was a tendency to differentiate median hTERT levels with respect to response rates (complete response + partial response: 33.1 versus stable disease + progressive disease: 50.7 ng/ml, p = 0.12), but other clinical variables such as age, gender, performance status, stage, histology, and number of metastatic locations were not associated with hTERT . In multivariate analysis, hTERT was an independent prognostic variable for both TTP (hazard ratio: 1.44, p p = 0.007). Conclusions: In advanced NSCLC, high pretreatment circulating hTERT level is an independent poor prognostic marker for TTP and OS. Circulating DNA is a noninvasive marker, which may help to improve the prognostic profile of these patients.