6550 Background: Peripheral blood stem cell transplantation (PBSCT) is a key component in the treatment of various malignancies. Preparatory regimens for PBSCT often include total body irradiation (TBI). Pulmonary toxicity is often prominent, and is felt to be related to total lung dose and dose rate. The Radiation Oncology Branch of the National Institute of Health initially administered TBI without lung shielding, however shielding was added in 2002. Pulmonary function testing (PFT) was undertaken both before and after stem cell transplant and TBI for all patients. The PFT results were analysed to test the hypothesis that TBI patients with pre-treatment combined ventilation/diffusion capacity deficits, defined as both FEV1 and DLCO below 100% predicted, would benefit most from reduction of lung dose. Methods: From 1997–2004, 146 consecutive patients with hematologic malignancies received fractionated TBI before PBSCT. The first 85 patients were treated without lung dose reduction to 13.6 Gray (Gy). Thereafter, total body dose was decreased to 12 Gy (1.5 Gy BID for 4 days). Initially, lung dose was limited to 9 Gy by use of lung shielding. Later lung dose was reduced to 6 Gy. All patients received PFTs prior to treatment, 90 days after treatment, and annually. Results: Median F/U was 44 months (range 12–90 months). Sixty-one patients had combined ventilation/diffusion capacity deficits defined as both a forced expiratory volume in the first second (FEV1) and a diffusion capacity of carbon dioxide (DLCO) less than 100% predicted. Of these 61, 27 had lung dose reduction and 34 did not. One-year survival was 71% versus 50% with and without lung dose reduction respectively (log rank test p=0.042). Eighty-five patients had FEV1 and/or DLCO greater than or equal to 100% predicted; 34 were treated with lung dose reduction and 51 without. In both groups, 1 year survival was 70%. Conclusions: Among patients treated without lung dose reduction, survival was significantly worse among those with pretreatment combined ventilation/diffusion capacity deficits. Among those with combined ventilation/diffusion capacity deficits, lung dose reduction significantly improved survival. No significant financial relationships to disclose.

Purpose/Objective: This analysis was undertaken to determine the value of PFTs in predicting risk of all cause mortality after fractionated TBI performed with or without lung shielding.Materials/Methods: On prospective IRB approved protocols, from July 1997 through August 2004, 146 consecutive patients with hematologic malignancies received TBI as part of their conditioning regimen for peripheral blood stem cell transplantation. Prior to 2001, 85 patients received 13.60 Gy delivered in eight fractions of 170 cGy BID via opposed lateral technique without lung shielding. After 2002, new protocols stipulated a total body dose of 1200 cGy (150 cGy BID for 4 days) and stipulated a dose of 600cGy to the lung. The lungs were blocked with partial transmission blocks in the lateral fields, so that about 50% of the lung received 50% of the dose based on dose volume histograms. AP/PA beams were then added to the laterally blocked area with full lung blocks. The patients received PFTs prior to treatment, 90 days after treatment, and annually. Follow-up was complete for all patients.Results: For the entire cohort, the median F/U was 44 months (range 8–90 months). A total of 30 patients were found to have an FEV1 less than 95% predicted of normal and a DLCO less than 80% predicted of normal. Of these 30, 15 received TBI without lung shielding and 15 with lung shielding. 12 of the 15 patients who had lung shielding survived compared to only 3 of the 15 without lung shielding (p=0.002). Of the 116 patients with FEV1 greater than 0.95% predicted or DLCO greater than 80% predicted, 46 were treated with lung shielding and 70 without. 33 of 46 patients treated with lung shielding survived (72%) compared to 42 of 70 treated without lung shielding (60%) (p=.235).Conclusions: All patients seemed to benefit from the addition of lung shielding during TBI. However, this benefit was most significant in those patients with suboptimal FEV1 and DLCOs. Lung shielding should be considered for use in patients undergoing fractionated TBI treatment if they have a FEV1<95% predicted and a DLCO<80% predicted. Purpose/Objective: This analysis was undertaken to determine the value of PFTs in predicting risk of all cause mortality after fractionated TBI performed with or without lung shielding. Materials/Methods: On prospective IRB approved protocols, from July 1997 through August 2004, 146 consecutive patients with hematologic malignancies received TBI as part of their conditioning regimen for peripheral blood stem cell transplantation. Prior to 2001, 85 patients received 13.60 Gy delivered in eight fractions of 170 cGy BID via opposed lateral technique without lung shielding. After 2002, new protocols stipulated a total body dose of 1200 cGy (150 cGy BID for 4 days) and stipulated a dose of 600cGy to the lung. The lungs were blocked with partial transmission blocks in the lateral fields, so that about 50% of the lung received 50% of the dose based on dose volume histograms. AP/PA beams were then added to the laterally blocked area with full lung blocks. The patients received PFTs prior to treatment, 90 days after treatment, and annually. Follow-up was complete for all patients. Results: For the entire cohort, the median F/U was 44 months (range 8–90 months). A total of 30 patients were found to have an FEV1 less than 95% predicted of normal and a DLCO less than 80% predicted of normal. Of these 30, 15 received TBI without lung shielding and 15 with lung shielding. 12 of the 15 patients who had lung shielding survived compared to only 3 of the 15 without lung shielding (p=0.002). Of the 116 patients with FEV1 greater than 0.95% predicted or DLCO greater than 80% predicted, 46 were treated with lung shielding and 70 without. 33 of 46 patients treated with lung shielding survived (72%) compared to 42 of 70 treated without lung shielding (60%) (p=.235). Conclusions: All patients seemed to benefit from the addition of lung shielding during TBI. However, this benefit was most significant in those patients with suboptimal FEV1 and DLCOs. Lung shielding should be considered for use in patients undergoing fractionated TBI treatment if they have a FEV1<95% predicted and a DLCO<80% predicted.