Total body irradiation and pneumonitis risk: a review of outcomes

Simvastatin attenuates radiation-induced murine lung injury and dysregulated lung gene expression

Novel therapies are desperately needed for radiation-induced lung injury (RILI), which, despite aggressive corticosteroid therapy, remains a potentially fatal and dose-limiting complication of thoracic radiotherapy. We assessed the utility of simvastatin, an anti-inflammatory and lung barrier-protective agent, in a dose- and time-dependent murine model of RILI (18-(25 Gy). Simvastatin reduced multiple RILI indices, including vascular leak, leukocyte infiltration, and histological evidence of oxidative stress, while reversing RILI-associated dysregulated gene expression, including p53, nuclear factor-erythroid-2-related factor, and sphingolipid metabolic pathway genes. To identify key regulators of simvastatin-mediated RILI protection, we integrated whole-lung gene expression data obtained from radiated and simvastatin-treated mice with protein-protein interaction network analysis (single-network analysis of proteins). Topological analysis of the gene product interaction network identified eight top-prioritized genes (Ccna2a, Cdc2, fcer1 g, Syk, Vav3, Mmp9, Itgam, Cd44) as regulatory nodes within an activated RILI network. These studies identify the involvement of specific genes and gene networks in RILI pathobiology, and confirm that statins represent a novel strategy to limit RILI.

Genistein protects against biomarkers of delayed lung sequelae in mice surviving high-dose total body irradiation

The effects of genistein on 30-day survival and delayed lung injury were examined in C57BL/6J female mice. A single subcutaneous injection of vehicle (PEG-400) or genistein (200 mg/kg) was administered 24 h before total body irradiation (7.75 Gy (60)Co, 0.6 Gy/min). Experimental groups were: No treatment + Sham (NC), Vehicle + Sham (VC), Genistein + Sham (GC), Radiation only (NR), Vehicle + Radiation (VR), Genistein + Radiation (GR). Thirty-day survivals after 7.75 Gy were: NR 23%, VR 53%, and GR 92%, indicating significant protection from acute radiation injury by genistein. Genistein also mitigated radiation-induced weight loss on days 13-28 postirradiation. First generation lung fibroblasts were analyzed for micronuclei 24 h postirradiation. Fibroblasts from the lungs of GR-treated mice had significantly reduced micronuclei compared with NR mice. Collagen deposition was examined by histochemical staining. At 90 days postirradiation one half of the untreated and vehicle irradiated mice had focal distributions of small collagen-rich plaques in the lungs, whereas all of the genistein-treated animals had morphologically normal lungs. Radiation reduced the expression of COX-2, transforming growth factor-beta receptor (TGFbetaR) I and II at 90 days after irradiation. Genistein prevented the reduction in TGFbetaRI. However, by 180 days postirradiation, these proteins normalized in all groups. These results demonstrate that genistein protects against acute radiation-induced mortality in female mice and that GR-treated mice have reduced lung damage compared to NR or VR. These data suggest that genistein is protective against a range of radiation injuries.

Fatal pneumonitis in children with metastatic rhabdomyosarcoma following whole lung radiotherapy and sequential epirubicin

Interstitial pneumonitis is a recognized complication following whole lung radiotherapy. We report two cases in which fatal pneumonitis appeared to be precipitated by the administration of epirubicin-containing combination chemotherapy within 7 weeks of completion of whole lung radiotherapy. These cases highlight a potentially fatal interaction between radiotherapy and modern chemotherapy regimens.

Fludarabine allows dose reduction for total body irradiation in pediatric hematopoietic stem cell transplantation

PURPOSE

To examine, in the setting of total body irradiation (TBI) for the preparation of pediatric hematopoietic stem cell transplantation (HSCT), whether TBI dose can be reduced without compromising the efficacy of a regimen consisting of fludarabine and radiotherapy; and whether there is any increased risk of pulmonary toxicity due to the radiosensitizing effect of fludarabine.

METHODS AND MATERIALS

A total of 52 pediatric patients with hematologic malignancies received TBI-based conditioning regimens in preparation for allogeneic HSCT. Twenty-three patients received 12 Gy in 4 daily fractions in combination with cyclophosphamide, either alone or with other chemotherapeutic and biologic agents. Twenty-nine patients received 9 Gy in 3 fractions in conjunction with fludarabine and melphalan. Clinical and radiation records were reviewed to determine engraftment, pulmonary toxicity (according to Radiation Therapy Oncology Group criteria), transplant-related mortality, recurrence of primary disease, and overall survival.

RESULTS

The two groups of patients had comparable pretransplant clinical characteristics. For the 12-Gy and 9-Gy regimens, the engraftment (89% and 93%; p = 0.82), freedom from life-threatening pulmonary events (65% and 79%; p = 0.33), freedom from relapse (60% and 73%; p = 0.24), and overall survival (26% and 47%; p = 0.09) were not statistically different.

CONCLUSIONS

The addition of fludarabine and melphalan seems to allow the dose of TBI to be lowered to 9 Gy without loss of engraftment or antitumor efficacy.

Extracorporeal membrane oxygenation for support of children after hematopoietic stem cell transplantation: the Extracorporeal Life Support Organization experience

PURPOSE

Extracorporeal membrane oxygenation (ECMO) is a means of respiratory and hemodynamic support for patients failing conventional therapies. Children requiring hematopoietic stem cell transplantation who develop complications during therapy may require ECMO. Such patients pose medical and ethical challenges for clinicians considering initiation of ECMO. The authors review the outcomes of these patients and propose recommendations.

METHODS

The Extracorporeal Life Support Organization Registry was queried for all patients younger than 18 years with an International Classification of Diseases, Ninth Revision, or Current Procedural Terminology code related to bone or stem cell transplant.

RESULTS

Nineteen children in the registry met inclusion criteria. The median age was 9.6 years (7 months to 17.5 years). Initiation of ECMO was for pulmonary support (n = 17), cardiac support (n = 1), or cardiopulmonary resuscitation (n = 1). The median duration of ECMO support was 5.1 days (range, 30 hours to 42 days). Pulmonary infections included 3 parainfluenza, 2 Pneumocystis carinii, 1 influenza A, and 1 respiratory syncytial virus. Overall, 15 (79%) died during their ECMO run, whereas only 4 (21%) survived to come off ECMO. Furthermore, of those who survived their ECMO run, only one patient survived to discharge from the hospital. Risk factors for death on ECMO include development of renal complications and development of multiorgan dysfunction.

CONCLUSION

Patients who require ECMO for cardiopulmonary support after hematopoietic stem cell transplantation have a poor prognosis. Clinicians must be cautious in presenting this option to parents and present them with appropriate expectations in this high-risk population.

Modified total body irradiation as a planned second high-dose therapy with stem cell infusion for patients with bone-based malignancies

PURPOSE

To estimate the maximum tolerated dose of hyperfractionated total marrow irradiation (TMI) as a second consolidation after high-dose chemotherapy with autologous or syngeneic blood stem cell transfusion for patients with bone/bone marrow-based malignant disease.

PATIENTS AND METHODS

Fifty-seven patients aged 3-65 years (median, 45 years), including 21 with multiple myeloma, 24 with breast cancer, 10 with sarcoma, and 2 with lymphoma, were treated with 1.5 Gy administered twice daily to a total dose of 12 Gy (n = 27), 13.5 Gy (n = 12), and 15 Gy (n = 18). Median time between the 2 transplants was 105 days (range, 63-162 days).

RESULTS

All patients engrafted neutrophils (median, Day 11; range, Day 9-23) and became platelet independent (median, Day 9; range, Day 7-36). There were 5 cases of Grade 3-4 regimen-related pulmonary toxicity, 1 at 12 Gy, and 4 at 15 Gy. Complete responses, partial responses, and stabilizations were achieved in 33%, 26%, and 41% of patients, respectively. Kaplan-Meier estimates of 5-year progression-free survival and overall survival for 56 evaluable patients are 24% and 36%, respectively. Median time of follow-up among survivors was 96 months (range, 77-136 months).

CONCLUSION

Total marrow irradiation as a second myeloablative therapy is feasible. The estimated maximum tolerated dose for TMI in a tandem transplant setting was 13.5 Gy. Because 20% of patients are surviving at 8 years free of disease, further studies of TMI are warranted.

Feasibility study of helical tomotherapy for total body or total marrow irradiationa)

Total body radiation (TBI) has been used for many years as a preconditioning agent before bone marrow transplantation. Many side effects still plague its use. We investigated the planning and delivery of total body irradiation (TBI) and selective total marrow irradiation (TMI) and a reduced radiation dose to sensitive structures using image-guided helical tomotherapy. To assess the feasibility of using helical tomotherapy, (A) we studied variations in pitch, field width, and modulation factor on total body and total marrow helical tomotherapy treatments. We varied these parameters to provide a uniform dose along with a treatment times similar to conventional TBI (15-30 min). (B) We also investigated limited (head, chest, and pelvis) megavoltage CT (MVCT) scanning for the dimensional pretreatment setup verification rather than total body MVCT scanning to shorten the overall treatment time per treatment fraction. (C) We placed thermoluminescent detectors (TLDs) inside a Rando phantom to measure the dose at seven anatomical sites, including the lungs. A simulated TBI treatment showed homogeneous dose coverage (+/-10%) to the whole body. Doses to the sensitive organs were reduced by 35%-70% of the target dose. TLD measurements on Rando showed an accurate dose delivery (+/-7%) to the target and critical organs. In the TMI study, the dose was delivered conformally to the bone marrow only. The TBI and TMI treatment delivery time was reduced (by 50%) by increasing the field width from 2.5 to 5.0 cm in the inferior-superior direction. A limited MVCT reduced the target localization time 60% compared to whole body MVCT. MVCT image-guided helical tomotherapy offers a novel method to deliver a precise, homogeneous radiation dose to the whole body target while reducing the dose significantly to all critical organs. A judicious selection of pitch, modulation factor, and field size is required to produce a homogeneous dose distribution along with an acceptable treatment time. In addition, conformal radiation to the bone marrow appears feasible in an external radiation treatment using image-guided helical tomotherapy.