Radiation pneumonitis; early diagnosis and associated factors

Background and aim: radiotherapy (RT) is essential in the treatment of non small cell lung cancer (NSCLC). However, lung radiosensitivity is the main limitation. The aim of this study was to evaluate the incidence of radiation pneumonitis and possible markers for early detection Methods: 14 patients with NSCLC treated with chemotherapy-radiotherapy were enrolled in a prospective study between 2011 and 2013. Anthropometric values, lung function, tumor features and RT dosimetric data were collected. Bronchoalveolar lavage (BAL) was performed in both lungs before RT and at the third week of treatment. Radiation pneumonitis was scored according the “Common Terminology Criteria for Adverse Events v4.0”. Patients with pneumonitis grade 1 and 3 were selected to perform the molecular analysis by using “Human Cytokine Array Panel A” (R&D Systems). Results: 35.75% of the patients had pneumonitis grade 1, 20% grade 2, 35.75% grade 3 and 6.66% grade 4. 4 patients developed pneumonitis in the lung without tumour. Lung diffusion capacity for carbon monoxide (DLCO) was the most sensitive parameter for determining the existence of early lung damage (p=0.04). Development of radiation pneumonitis was not associated with lung function or dosimetric data. BAL protein expression before RT differs from the lung that develops grade 1 pneumonitis and grade 3. In both cases, RT induces changes in bilateral BAL protein expression, mainly PAI-1, IL-1ra, MIF, and CXCL-1. Conclusion: Incidence of radiation pneumonitis is greater than previously reported. DLCO is the most sensitive parameter for its early detection. Risk could have a relationship with the basal lung biomolecular condition. RT induces biological changes in both lungs.