Clinical results and the Essen concept of TBI

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.

Positive serum crossmatch as predictor for graft failure in HLA-mismatched allogeneic blood stem cell transplantation

BACKGROUND

Evaluation of patient sera for complement-fixing anti-donor antibodies (serum crossmatch [XM]) before allogeneic blood stem cell transplantation (BSCT) is routine in most centers. However, in contrast to kidney transplantation, the predictive value of a positive XM for outcome of BSCT is still unclear, and a positive XM is presently not regarded as an absolute contraindication to proceed to transplant.

METHODS

To clarify the role of a positive XM as predictor for overall survival (OS) and graft failure (GF) after BSCT, a retrospective, single-center, matched-pair analysis was performed. Enrolled were all XM-positive BSCT performed at our institution from 1985 to 2000 (n=30). Controls (n=30) were matched for disease, disease stage, patient age, period of transplant, conditioning regimen, protocol for prevention of graft-versus-host disease, and type of donor (related vs. unrelated, HLA-identical vs. HLA-mismatched).

RESULTS

Multivariate statistical analysis of all enrolled 60 transplants revealed GF as the all-dominating, independent risk factors for low OS (relative risk [RR]: 59.5, P<0.0001). Univariate (Kaplan-Meier) analysis could attribute inferior OS and high incidence of GF to the subgroup of HLA-mismatched, XM-positive transplants (P=0.01).

CONCLUSIONS

A XM should always be performed in patients awaiting a BSCT from HLA-mismatched donors, because a positive XM is a predictor for inferior OS due to GF in BSCT.

The clinical application of dynamic shielding and imaging in moving table total body irradiation

The moving table technique for total body irradiation (MTT TBI) has some advantages in regard to dose homogeneity, patient positioning and comfort. However, divergence of the radiation field coupled with patient motion necessitates corresponding motion of the shielding blocks and verification film so that penumbra is minimized. MTT TBI system is presented, together with dose calculations, incorporating moving trays for shields and film to ensure dose delivery with minimal penumbra of the blocked field.

The accuracy of dose determination during total body irradiation

AIM

The aim of this work was to estimate the error in dose calculations, to check the agreement between the measured and calculated doses and to analyse dose discrepancies in the group of patients undergoing total body irradiation.

PATIENTS AND METHODS

A combination of lateral and anterior-posterior fields was used in 8 fractions and on 4 consecutive days. Doses were preliminarily calculated and then measured in vivo by thermoluminescent, semiconductor and ionization dosimeters attached to the body in 10 representative transverse cross-sections. Calculations and measurements were carried out for the beam at the body entry and exit. The error in dose calculations was estimated for each reference point. Dose deviations between calculations and measurements were analysed using the Student's t-test.

RESULTS

The error in preliminary dose calculations ranged from 3% to 15% (Table 1). Standard deviations of the measurements and percent deviations from the calculations exceeded 10% only for the lung and neck exits (Table 3). Average thermoluminescent readings were 6% higher than the corresponding semiconductor readings. The measured doses fitted the calculated values within the limit of error, except for the lung, head and neck exits for the whole group, depending on the type of fields used (Table 4).

Total body irradiation with translation method

Total body irradiation (TBI) using translation method has been applied in 20 patients prior to bone marrow transplantation (BMT). This paper describes the technique of irradiation as well as the results of in vivo dosimetry in patients undergoing TBI. According to our experience, the translation technique is comfortable for patient and provides homogeneous dose distribution over the whole body.

Single dose versus fractionated total body irradiation before bone marrow transplantation: radiobiological and clinical considerations

PURPOSE

This present review is intended to evaluate the specific influence of fractionation of total body irradiation on the outcome of a subsequent bone marrow transplantation.

METHODS AND MATERIALS

Available experimental and clinical data on the influence of fractionation on leukemia cell killing, immunosuppression, and sparing of normal tissues were analyzed.

RESULTS

Review of available data shows: (a) The role of fractionation on leukemia cell killing may vary with the leukemia type. For acute nonlymphoblastic leukemia, a few experimental and several clinical studies show no or little fractionation effect; a 12-13 Gy fractionated scheme could, therefore, be more efficient than a conventional 10 Gy single dose total body irradiation. For chronic myelogenous leukemia, some sensitivity to fractionation is suggested, so that an increase in total or fractional dose may be necessary in fractionated schemes to equate the efficacy of a 10 Gy single dose. For acute lymphoblastic leukemia, a high fractionation sensitivity was observed for some leukemic cell lines in vitro, without undisputable clinical confirmation for the moment. (b) Numerous experimental studies have demonstrated that the immunosuppressive effect of total body irradiation, a major determinant of engraftment, is highly fractionation sensitive. In humans, high rates of graft failures have been reported when T-cell depletion of the graft was associated to fractionated total body irradiation schedules. (c) A large amount of radiobiological and clinical data have demonstrated that late radiation-induced injuries to normal tissues and organs are highly fractionation sensitive. However, in a context of total body irradiation for bone marrow transplantation, the number of other determinants of normal tissue damage makes it difficult to demonstrate a clear-cut advantage of fractionated over single dose scheme, with a possible exception for children.

CONCLUSIONS

In 1994, available data suggest that very cautious attempts could be made to adapt total body irradiation schedules to the potential normal tissue toxicity, T-cell depletion, and to the type of leukemia.