Evaluating the relationship between dosimetric and clinical indicators in lung tissue among breast cancer patients

Purpose: Breast cancer is the most common type of cancer among women. It is important to prevent damages to normal tissues, particularly to lung tissue, in breast cancer radiation therapy. Radiation pneumonitis is mainly related to the irradiated volume of lung. In this study, relationship between clinical and dosimetric parameters of lung tissue was evaluated among breast cancer patients. Methods: Dosimetric and clinical data of 118 patients suffering from breast cancer including stages II/III, undergone mastectomy and/or modified radical mastectomy, and received 8 stages chemotherapy, were studied in Mahdieh radiotherapy center in Hamedan. Treatment planning was done for delivering 50 Gy dose to PTV in 25 fractions. IV20 parameter was considered as the response parameter and the correlation of parameters was calculated. Also based on univariate logistic regression model, the relationship between effective predictive and response parameters was performed. Results: Using evaluation of the correlation between predictive parameters and IV20, the effective parameters are age, MLD, CLD, irradiated lung volume, mean dose, and PTV. Based on the model, there is significant relationship between response and effective predictive parameters. Conclusion: A decrease in the CLD parameter for reducing lung damage is suggested.Validation parameters of the proposed model showed that this model can replace the predictive index IV20; and it can give a good estimation of damage to the lung tissue during breast cancer radiotherapy. It can result in lung damage reduction and enhancement in the quality of life of patients.

Keywords:

Breast cancer , Radiation therapy , Lung damage , Predictive model