Prediction of over-all pulmonary function loss in relation to the 3-D dosedistribution for patients with breast cancer and malignant lymphoma

Purpose: To predict the changes in pulmonary function tests (PFTs) 3-4 mont hs after radiotherapy based on the three-dimensional (3-D) dose distributio n and taking into account patient- and treatment-related factors. Methods: For 81 patients with malignant lymphoma and breast cancer, PFTs (V -A, VC, FEV1 and T-L,T-COc) were performed prior to and 3-4 months after ir radiation and dose-effect relations for early changes in local perfusion, v entilation and air-filled fraction were determined using correlated CT and SPECT data. The 3-D dose distribution of each patient was converted into fo ur different dose-volume parameters, i.e. the mean dose in the lung and thr ee overall response parameters (ORPs, which represent the average local inj ury over the complete lung). ORPs were determined using the dose-effect rel ations for early changes in local perfusion, ventilation and air-filled fra ction. Correlation coefficients were calculated between these dose-volume p arameters and the changes in PFTs. In addition, the impact of the variables chemotherapy (MOPP/ABV and CMF), tamoxifen, smoking, age and gender on the relation between the mean lung dose and the relative changes in PFTs follo wing radiotherapy was studied using multiple regression analysis. Results: The mean lung dose proved to be the easiest parameter to predict t he reduction in PFTs 3-4 months following radiotherapy. For all patients th e relation between the mean lung dose and the changes in PFTs could be desc ribed with one regression line through the origin and a slope of 1% reducti on in PFT for each increase of 1 Gy in mean lung dose. Smoking and CMF chem otherapy influenced the reduction in PFTs significantly for V-A and T-L,T-C Oc, respectively. Patients treated with MOPP/ABV prior to radiotherapy had lower pre-radiotherapy PFTs than other patient groups, but did not show fur ther deterioration after radiotherapy (at 3-4 months). Conclusions: The relative reduction in V-A, VC, FEV1 and T-L,T-COc 3-4 mont hs after radiotherapy for breast cancer and malignant lymphoma can be estim ated before radiotherapy based on the mean lung dose of each individual pat ient and taking into account the use of chemotherapy and smoking habits of the patient. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.