Effect of dose rate on pulmonary toxicity in patients with hematolymphoid malignancies undergoing total body irradiation

Radiat Oncol. 2018 Sep 18;13(1):180. doi: 10.1186/s13014-018-1116-9.

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 transplantation-related 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: Dose rate; Hematolymphoid malignancy; Pulmonary toxicity; Total body irradiation.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Child
  • Child, Preschool
  • Dose Fractionation, Radiation
  • Female
  • Graft vs Host Disease / prevention & control
  • Hematologic Neoplasms / mortality
  • Hematologic Neoplasms / radiotherapy*
  • Hematopoietic Stem Cell Transplantation* / mortality
  • Humans
  • Infant
  • Lung / radiation effects*
  • Male
  • Middle Aged
  • Radiation Injuries*
  • Radiotherapy Dosage
  • Retrospective Studies
  • Transplantation Conditioning / adverse effects*
  • Transplantation Conditioning / methods
  • Transplantation Conditioning / mortality
  • Whole-Body Irradiation / adverse effects*
  • Whole-Body Irradiation / methods
  • Whole-Body Irradiation / mortality
  • Young Adult