RECOVERY OF OVERALL AND LOCAL LUNG-FUNCTION LOSS 18 MONTHS AFTER IRRADIATION FOR MALIGNANT-LYMPHOMA

Purpose: To determine local and overall pulmonary injury 3 to 18 month s after irradiation and to investigate whether the changes in overall lung function can be predicted using the three-dimensional (3-D) dose distribution in combination with dose-effect relations for local injur y; and to study the influence of chemotherapy on the injury. Patient a nd Methods: Local perfusion (Q), ventilation (V), and tissue density w ere measured in 25 patients treated for malignant lymphoma, before, 3 to 4 months after, and 18 months after irradiation. Dose-effect relati ons for local injury, calculated using correlated single-photon emissi on computed tomographic (SPECT) and computed tomographic (CT) data, we re combined with the 3-D dose distribution, to calculate the estimated mean local changes over the complete lung for each patient. The resul t was correlated with the actual changes in pulmonary function. Result s: A dose-dependent increase in injury was observed 3 to 4 months afte r irradiation, which at 18 months had recovered by approximately 50% t o 60%. The estimated mean relative reduction of local Q predicted the change in overall lung function within 10% of the actually observed va lues in 63% to 73% of patients. Chemotherapy given before radiotherapy enhanced radiation-induced reduction of local Q significantly, with d ose-modifying factors of 1.22 and 1.37 at 3 to 4 months and 18 months, respectively. Conclusion: Partial recovery of radiation-induced reduc tion of local and overall lung function was observed at 18 months afte r irradiation. The overall functional outcome of most patients could b e well predicted, based on the estimated mean local injury over the co mplete lung. Chemotherapy given before radiotherapy enhanced the radia tion-induced reduction of local Q. (C) 1996 by American Society of Cli nical Oncology.