Factors associated with pulmonary toxicity after myeloablative conditioning using fractionated total body irradiation

The Burden of Survivorship on Hematological Patients-Long-Term Analysis of Toxicities after Total Body Irradiation and Allogeneic Stem Cell Transplantation

Simple Summary

Total body irradiation is an essential large-field technique enabling myeloablation before allogeneic stem cell transplantation. With its field encompassing all organs, a diverse spectrum of toxicities may arise. This work analyzes long-term pulmonary, cardiac, ocular, neurological and renal toxicities in a monocentric patient cohort and identifies possible risk factors. Both the number of patients and the duration of the follow-up period exceed those of many comparable studies in the literature.

Abstract

Total body irradiation is an effective conditioning modality before autologous or allogeneic stem cell transplantation. With the whole body being the radiation target volume, a diverse spectrum of toxicities has been reported. This fact prompted us to investigate the long-term sequelae of this treatment concept in a large patient cohort. Overall, 322 patients with acute leukemia or myelodysplastic syndrome with a minimum follow-up of one year were included (the median follow-up in this study was 68 months). Pulmonary, cardiac, ocular, neurological and renal toxicities were observed in 23.9%, 14.0%, 23.6%, 23.9% and 20.2% of all patients, respectively. The majority of these side effects were grades 1 and 2 (64.9–89.2% of all toxicities in the respective categories). The use of 12 Gray total body irradiation resulted in a significant increase in ocular toxicities (p = 0.013) and severe mucositis (p < 0.001). Renal toxicities were influenced by the age at transplantation (relative risk: 1.06, p < 0.001) and disease entity. In summary, total body irradiation triggers a multifaceted, but manageable, toxicity profile. Except for ocular toxicities and mucositis, a 12 Gray regimen did not lead to an increase in long-term side effects.

Survivors of allogeneic bone marrow transplants in childhood report no significant long-term respiratory symptoms: A single-center analysis over 20 years

Pulmonary toxicity is documented in long-term survivors of allogeneic BMT. No studies have specifically evaluated late pulmonary symptomatology in these patients. 85 long-term pediatric survivors were sent a validated questionnaire of pulmonary symptomatology. Demographic and clinical data were retrospectively collected from the respondents medical records. Response rate was 52.9%. Mean follow-up post-BMT of those who responded was 12.3 years. Mean pulmonary symptom scores were low (0.78). There was no significant difference in symptoms between patients who underwent MA conditioning with or without TBI. These results are reassuring that long-term survivors of pediatric BMT have few respiratory symptoms which do not impact on activities of daily living.

Pulmonary Toxicity after Total Body Irradiation-An Underrated Complication? Estimation of Risk via Normal Tissue Complication Probability Calculations and Correlation with Clinical Data

Simple Summary

Total body irradiation is an integral part of many conditioning regimens prior to allogeneic stem cell transplantation. It is a large-field technique affecting all organs at risk, of which the lungs are critical for patient survival. However, the precise rates of long-term pulmonary toxicities are unknown. This analysis provides a large patient cohort with long-term follow-up investigating TBI sequelae. Additionally, we present normal tissue complication probability calculations for acute and chronic lung toxicities to enable comparison between biophysical and real-world data. To our knowledge, this is the first adaption of this model to a total-body irradiation patient cohort, which will help to evaluate the feasibility and appropriateness of this approach.

Abstract

Total body irradiation (TBI) is an essential part of various conditioning regimens prior to allogeneic stem cell transplantation, but is accompanied by relevant (long-term) toxicities. In the lungs, a complex mechanism induces initial inflammation (pneumonitis) followed by chronic fibrosis. The hereby presented analysis investigates the occurrence of pulmonary toxicity in a large patient collective and correlates it with data derived from normal tissue complication probability (NTCP) calculations. The clinical data of 335 hemato-oncological patients undergoing TBI were analyzed with a follow-up of 85 months. Overall, 24.8% of all patients displayed lung toxicities, predominantly pneumonia and pulmonary obstructions (13.4% and 6.0%, respectively). NTCP calculations estimated median risks to be 20.3%, 0.6% and 20.4% for overall pneumonitis (both radiological and clinical), symptomatic pneumonitis and lung fibrosis, respectively. These numbers are consistent with real-world data from the literature and further specify radiological and clinical apparent toxicity rates. Overall, the estimated risk for clinical apparent pneumonitis is very low, corresponding to the probability of non-infectious acute respiratory distress syndrome, although the underlying pathophysiology is not identical. Radiological pneumonitis and lung fibrosis are expected to be more common but require a more precise documentation by the transplantation team, radiologists and radiation oncologists.

Adverse Effects of Total Body Irradiation: A Two-Decade, Single Institution Analysis

Purpose

Several adverse effects have been reported in the literature associated with total body irradiation (TBI). Reports of the adverse effects of TBI have been primarily drawn from single-institution retrospective analyses. We report, to our knowledge, one of the largest cohorts of patients treated with TBI using multiple preparative chemotherapy and radiation regimens.

Methods and Materials

A retrospective chart review was performed for all 705 patients treated with TBI at our institution from 1995 to 2017. Based on availability of TBI records, 622 patients (88%) had sufficient evaluable documentation for analysis. Patients received 1 of 4 conditioning regimens: busulfan-fludarabine, 2 Gy (BUFLU); fludarabine-melphalan, 2 Gy (FLUMEL); cyclophosphamide, 12 Gy fractionated (CY); or etoposide, 12 Gy fractionated (VP16). Individual patients were evaluated for 13 specific recognized adverse effects based on the Common Terminology Criteria for Adverse Events, version 5.0.

Results

Mucositis (grade 3) was the most common serious adverse effect and occurred most frequently in the group receiving the VP16 12 Gy regimen (40% vs less than 14% in each of the other groups). Serious febrile neutropenia (grade 3-5) was less frequent (24%) among patients receiving CY than among those receiving the other conditioning regimens (more than 38% in each of the other groups). The incidence of serious lung infection was less common (5%) in patients receiving CY than in those receiving VP16 (18%). There was a higher frequency of grade 3-5 diarrhea among those receiving FLUMEL (5%) and VP16 (4%) than in the other groups (<3%) (P = .034). Otherwise, there were no detectable differences in serious toxicity by regimen for the 13 adverse effects reviewed. Only 2 secondary malignancies were reported, and both were in the BUFLU group. Cataract formation occurred in approximately 16% of patients overall, and the rates were similar across regimens. Median time to cataract formation was 1 to 4 years across regimens, with cataracts occurring earlier in the 2-Gy regimens. The overall rate of grade ≥3 pneumonitis was approximately 2% across the entire cohort.

Conclusions

Our nearly 20-year TBI experience showed relatively low rates of radiation-related toxicities. However, cataracts were common with a relatively short onset time.

Estimation of radiation-induced, organ-specific, secondary solid-tumor occurrence rates with total body irradiation and total marrow irradiation treatments

PURPOSE

We aimed to predict and compare radiation-induced, organ-specific, secondary solid-tumor occurrence risks from conventional total body irradiation (TBI) and total marrow irradiation (TMI) for patients undergoing hematopoietic cell transplant.

METHODS AND MATERIALS

We retrospectively selected 20 patients who received TMI treatments before hematopoietic cell transplant. Ten patients (5 men; 5 women) received 12 Gy to the skeletal bones, lymph nodes, and spleen, and the other 10 patients (5 men; 5 women) received an escalated dose of 20 Gy to the same targets and 12 Gy to the brain and liver. A conventional TBI treatment plan was generated for each patient with a prescription dose of 12 Gy, using anterior-posterior and posterior-anterior photon beams with lung shielding and a chest wall boost with electron beams. Secondary cancer risks were estimated using linear-exponential and plateau models for major organs.

RESULTS

At the 12 Gy dose level, using the linear-exponential model, the total radiation-induced secondary solid-tumor risks for major organs were 159.3 ± 8.7 for men and 221.5 ± 14.4 for women per 10,000 people per year with the TMI plans, which is a reduction of 38.8% and 32.9%, respectively, compared with those with the TBI plans. At the 20 Gy dose level, the risks were 220.3 ± 8.3 for men and 298.5 ± 9.3 for women with the TMI plans, which is a reduction of 14.6% and 9.2%, respectively, compared with those with the 12 Gy TBI plans. Significant risk reductions were also found with the TMI plans using the plateau risk model.

CONCLUSIONS

At both the 12 Gy and 20 Gy prescription dose levels, a conditioning regimen using TMI could significantly lower overall radiation-induced secondary solid-tumor risks for major organs compared with a conditioning regimen with standard 12 Gy TBI. Clinical data from long-term follow-up studies are needed to verify the model predictions.

Feasibility of hybrid TomoHelical- and TomoDirect-based volumetric gradient matching technique for total body irradiation

BACKGROUND

Tomotherapy-based total body irradiation (TBI) is performed using the head-first position (HFP) and feet-first position (FFP) due to treatment length exceeding the 135 cm limit. To reduce the dosimetric variation at the match lines, we propose and verify a volumetric gradient matching technique (VGMT) by combining TomoHelical (TH) and TomoDirect (TD) modes.

METHODS

Two planning CT image sets were acquired with HFP and FFP using 15 × 55 × 18 cm3 of solid water phantom. Planning target volume (PTV) was divided into upper, lower, and gradient volumes. The junction comprised 2-cm thick five and seven gradient volumes (5-GVs and 7-GVs) to create a dose distribution with a gentle slope. TH-IMRT and TD-IMRT plans were generated with 5-GVs and 7-GVs. The setup error in the calculated dose was assessed by shifting dose distribution of the FFP plan by 5, 10, 15, and 20 mm in the longitudinal direction and comparing it with the original. Doses for 95% (D95) and 5% of the PTV (D5) were calculated for all simulated setup error plans. Absolute dose measurements were performed using an ionization chamber in the junction.

RESULTS

The TH&TD plan produced a linear gradient in junction volume, comparable to that of the TH&TH plan. D5 of the PTV was 110% of the prescribed dose when the FFP plan was shifted 0.7 cm and 1.2 cm in the superior direction for 5-GVs and 7-GVs. D95 of the PTV decreased to < 90% of the prescribed dose when the FF plan was shifted 1.1 cm and 1.3 cm in the inferior direction for 5-GVs and 7-GVs. The absolute measured dose showed a good correlation with the calculated dose in the gradient junction volume. The average percent difference (±SD) in all measured points was - 0.7 ± 1.6%, and the average dose variations between depths was - 0.18 ± 1.07%.

CONCLUSION

VGMT can create a linear dose gradient across the junction area in both TH&TH and TH&TD and can minimize the dose sensitivity to longitudinal setup errors in tomotherapy-based TBI.