Imaging features of radiation-induced lung disease and its relationship with clinical and dosimetric factors in breast cancer patients.

ABSTRACT

Aim: The aim is to extensively evaluate imaging features of radiation induced lung disease in breast cancer patients and to determine the relationship of imaging alterations with dosimetric parameters and patient related characteristics. Materials and Methods: A total of 76 breast cancer patients undergoing radiotherapy (RT) were studied retrospectively by case notes, treatment plans, dosimetric parameters, and chest computed tomography (CT) scans. Time intervals, that chest CT scans were acquired, were grouped as 1-6 months, 7-12 months, 13-18 months and more than 18 months after RT. Chest CTs (one or more for each patient) were assessed for the presence of ground glass opacity, septal thickening, consolidation/patchy pulmonary opacity/alveolar infiltrates, subpleural air cyst, air bronchogram, parenchymal bands, traction bronchiectasis, pleural/subpleural thickening and pulmonary volume loss. These alterations were scored by applying a system devised by Nishioka et al. Nishioka scores were analyzed for the relationship with clinical and dosimetric factors. Statistical Analysis Used IBM SPSS Statistics for Windows, version 22.0 (IBM Corp., Armonk, N.Y., USA) was used to analyze data. Results: Median follow-up time was 49 months. Advanced age and aromatase inhibitor intake were correlated with higher Nishioka scores for 1-6 months' period. However, both were found nonsignificant in multivariate analysis. Nishioka scores of CT scans acquired more than 12 months after RT were positively correlated with mean lung dose, V5, V20, V30, and V40. Receiver operating characteristic analysis revealed that V5 for ipsilateral lung was the most robust dosimetric parameter predicting chronic lung injury. V5 >41% indicates the development of radiological lung changes. Conclusions: Keeping V5 ≤41% for ipsilateral lung could provide avoiding chronic lung sequelae.