Can quantifying free-circulating DNA in plasma be used to identify subjects with high-grade pre-invasive endobronchial lesions?

Increased concentrations of free-circulating plasma DNA (cpDNA) are observed in patients with invasive cancer, including lung cancer. Whether cpDNA levels are elevated in subjects with high-grade pre-invasive lesions of lung squamous cell carcinoma (SqCC) and whether its detection may be of value for identifying subjects at the highest risk of developing lung SqCC is currently unknown. The present study assessed cpDNA levels in subjects with high- and low-grade pre-invasive squamous endobronchial lesions relative to patients with clinically overt lung SqCC and healthy controls using real-time quantitative PCR methodology. The median cpDNA levels of the patients with invasive lung SqCC (n=16) were significantly higher compared with those of the healthy controls (n=16; P<0.01), whereas the cpDNA levels in the subjects with pre-invasive lesions (n=20) did not differ from those of the controls (P=0.29). The cpDNA levels in subjects with high-grade pre-invasive lesions were highly similar to those diagnosed with low-grade pre-invasive lesions (P=0.85). Our data suggest that cpDNA levels are not increased during the pre-invasive stages of lung squamous carcinogenesis.