Torque teno virus DNA titre elevated in idiopathic pulmonary fibrosis with primary lung cancer

Background and objective: IPF is an independent risk factor for lung cancer, but the mechanism of this association has not fully been elucidated. The role of Torque teno virus (TTV) in respiratory disease is poorly understood, although it has been shown that infection with TTV is associated with the activity and prognosis of IPF. This study aimed to investigate the prevalence and titre of TTV DNA among patients with IPF and lung cancer. Methods: The presence of TTV DNA was determined by PCR in the sera of patients with both lung cancer and IPF (n = 22), patients with IPF only (n = 35), and patients with lung cancer only (n = 142). Results: TTV DNA was detectable in all patients with both IPF and lung cancer, in 94.3% of the patients with IPF only and 97.2% of the patients with lung cancer only. The TTV DNA titre in the patients with IPF and lung cancer was significantly higher than that in the patients with IPF only or lung cancer only. The percentage of TTV-positive patients with a high TTV titre in the IPF and lung cancer group was significantly higher than that in the IPF only group. Conclusions: These findings are the first report on the association between TTV and the complication of lung cancer in IPF and suggest that TTV infection might be associated with the development of lung cancer in IPF.