Plasma and urinary cyclic nucleotide levels in patients with lung cancer

In order to evaluate a clinical significance of cyclic adenosine 3′,5′-monophosphate (cAMP) and cyclic guanosine 3′, 5′-monophosphate (cGMP) as a marker, plasma and 24-hour urinary levels were measured in 84 patients with lung cancer, 25 normal subjects, 21 patients with benign lung disease, and 7 patients with benign lung tumor. Plasma cAMP levels in patients with lung cancer were significantly lower than those of normal subjects and patients with benign lung disease, while plasma cGMP levels in patients with lung cancer were significantly higher than those of normal subjects and patients with benign lung disease. Urinary cAMP levels in patients with lung cancer were similar to those of normal subjects, patients with benign lung disease and patients with benign lung tumor, whereas urinary cGMP levels were significantly higher than those of these three groups. Plasma cGMP levels were strongly correlated with urinary cGMP levels in patients with lung cancer. Plasma and urinary cGMP levels increased with the progression of clinical stages in patients with lung cancer. These results suggest that plasma and urinary cGMP levels are useful markers in patients with lung cancer.