Exhaled nitric oxide and radiation pneumonitis

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(1) Clinical study : We examined the exhaled NO level in patients with lung cancer that was higher in the patients with lung cancer than in control. Exhaled NO level decreased at the time 40 Gy irradiated and post radiotherapy. The elevation in exhaled NO of eight patients was triple or more than that seen in before radiotherapy. Three of these patiens showed signs of radiation pneumonitis. On the other hand, none of the other patients showed signs of radiation pneumonitis (p=0.002). Radiation therapy can lower exalted levels of NO, and the levels of exhaled NO level may be a useful for the early prediction of radiation pneumonitis.(2) Case Report : A 73 male with idiopathic interstitial pneumonitis underwent thoracic radiotherapy without chemotherapy for squamous cell lung cancer (T2N1M0). He showed elevation of exhaled NO level at 30 Gy/50 Gy after decreasing at 10-20 Gy. He also showed abnormal shadow in CT examination at 50 Gy. Although exhaled NO may have a merit to predict radiation pneumonitis before severe clinical symptom appeared, he died three months after radiotherapy for worsening of radiation pneumonitis.(3) Basic study : We examined alteration of NO level by irradiation in rat macrophage and smooth muscle cells. Radiation did not generate the expression of mRNA of iNOS and concentration of NO in medium, but enhance the expression of mRNA that was induced by LPS, IFN-gamma and IL1-beta. Therefore, radiation stimulation induced NO production through indirect action on the macrophage and smooth muscle cells,