Circulating DNA and lung cancer.

Lung cancer is the leading cause of cancer death worldwide. The majority of patients is diagnosed too late for curative treatment. There is an urgent need for a noninvasive test to identify early lung cancer. Although levels of circulating cell-free DNA in plasma or serum are higher in patients with lung cancer than in healthy controls, it is not yet clear whether this will be of diagnostic or prognostic significance. The finding that circulating DNA in lung cancer patients exhibits genetic and epigenetic changes typical of the tumor (including chromosome loss, oncogene activation, and tumor-suppressor gene inactivation by methylation) has led to intense efforts to determine whether these are sensitive and specific enough to be used clinically. Here we review the evidence on circulating DNA in lung cancer and consider possible future applications in patient management.