Effect of dose rate on pulmonary toxicity in patients with hematolymphoid malignancies undergoing total body irradiation
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RESEARCH
Open Access
Effect of dose rate on pulmonary toxicity in patients with hematolymphoid malignancies undergoing total body irradiation Dong-Yun Kim1, Il Han Kim1,4, Sung-Soo Yoon2,4, Hyoung Jin Kang3,4, Hee Young Shin3,4 and Hyun-Cheol Kang1*
Abstract Background: This study evaluated the effect of radiation dose rate in patients with hematolymphoid malignancies undergoing myeloablative conditioning with total body irradiation (TBI), for hematopoietic stem cell transplantation. Methods: The incidence of pulmonary toxicity (PT) and treatment efficacy were compared between the conventional (≥ 6 cGy/min) and reduced dose rate (< 6 cGy/min). Seventy-seven patients receiving once-daily TBI between 2000 and 2016 were reviewed. We compared the cumulative rate of PT, overall survival (OS), relapse, and transplantationrelated mortality (TRM) between conventional (n = 54) and reduced (n = 23) groups. Factors associated with PT were assessed in the presence of competing risks. Results: The median follow-up time was 40.7 months, and PT occurred in 50 patients (64.9%). On multivariate analyses, the groups classified by the dose rate (P = 0.010), total dose (P = 0.025), and conditioning regimen (P = 0.029) were significant factors for the development of PT. OS was significantly reduced when PT occurred (P < 0.001). However, the OS, relapse, and TRM were not different between the two groups. Conclusions: In summary, about two-thirds of the patients undergoing daily TBI experienced PT, which affected OS. Therefore, reducing the dose rate (less than 6 cGy/min) of TBI can decrease the risk of PT, without compromising the treatment efficacy. Keywords: Hematolymphoid malignancy, Total body irradiation, Pulmonary toxicity, Dose rate
Background Total body irradiation (TBI)-based myeloablative conditioning, followed by allogeneic stem cell transplantation, is conducted for patients with high-risk or relapsed hematolymphoid malignancies [1–3]. TBI has been used in 46% to 53% of allogeneic hematopoietic stem cell transplantations (HSCT) as a preconditioning component, with other chemotherapeutic agents [4]. There have been a wide variety of TBI doses and fractionation schedules used by each institution. The American College of Radiology (ACR) and the American Society for Radiation Oncology (ASTRO) recommended some basic principles with competing goals of * Correspondence: [email protected]; [email protected] 1 Department of Radiation Oncology, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea Full list of author information is available at the end of the article
anti-leukemic effects and toxicity reductions; however, a firm consensus has yet to be established [5]. Several complications limit the success of this treatment. Particularly, pulmonary toxicity (PT) is one of the most harmful sequelae of TBI [6–8]. PT is a life-threatening problem after TBI, followed by bone marrow transplantation (BMT), which together, account for 25–50% non-relapse deaths in prior studies [2,
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