Cataracts in patients receiving stem cell transplantation after conditioning with total body irradiation

Thiotepa, busulfan and fludarabine conditioning-regimen is a promising approach for older adult patients with acute lymphoblastic leukemia treated with allogeneic stem cell transplantation

For acute lymphoblastic leukemia (ALL) patients, total body irradiation (TBI)- based conditioning regimens are the first choice specially in young population. However, several studies have shown an equivalence in clinical outcomes with thiotepa-based conditioning regimen. We performed a retrospective study to evaluate the outcome of adult ALL patients who received allogeneic hematopoietic stem cell transplantation (allo-HCT) with a thiotepa-busulfan-fludarabine (TBF) myeloablative conditioning regimen with reduced toxicity. Fifty-five patients received a TBF regimen. The median age of the patients was 51 years (range, 17 to 72.4). Most patients had a diagnosis of B-ALL (93%) with 7% having T-ALL. Two - and 5-year overall survival was 73.2% and 64%, respectively. At 2 years, leukemia-free survival and GVHD-free, relapse-free survival were 59.5% and 57.6%, and at 5 years, 53.4% and 51.8%, respectively. The 5-year non-relapse mortality was 15%. The day 180 cumulative incidence (CI) of grade II-IV acute GVHD and grade III-IV acute GVHD were 38.2% and 5.5%, respectively. At 2 years, the CI of chronic GVHD and extensive chronic GVHD was 16.9% and 1.9%, respectively. Our study results do suggest that using TBF as the conditioning regimen in adult ALL patients is a promising option with acceptable toxicity.

The impact of different optimization strategies on the agreement between planned and delivered doses during volumetric modulated arc therapy for total marrow irradiation

Aim of the study

To evaluate the agreement between planned and delivered doses and its potential correlation with the plans' complexity subjected to dosimetric verification.

Material and methods

Four isocentre volumetric modulated arc therapy for total marrow irradiation plans optimized simultaneously with (P1) and without (P2) MU reduction were evaluated dosimetrically by γ method performed in a global mode for 4 combinations of γ-index criteria (2%/2 mm, 2%/3 mm, 3%/2 mm, and 3%/3 mm). The evaluation was conducted for 4 regions (head and neck, chest, abdomen and upper pelvis, and lower pelvis and thighs) that were determined geometrically by the isocentres. The Wilcoxon test was used to detect significant differences between γ passing rate (GPR) analysis results for the P1 and P2 plans. The Pearson correlation was used to check the relationship between GPR and the plans' complexity.

Results

Except for the head and neck region, the P2 plans had better GPRs than the P1 plans. Only for hard combinations of γ-index criteria (i.e. 2%/3 mm, 2%/2 mm) were the GPRs differences between P1 and P2 clinically meaningful, and they were detected in the chest, abdomen and upper pelvis, and lower pelvis and thighs regions. The highest correlations between GPR and the indices describing the plans' complexity were found for the chest region. No correlation was found for the head and neck region.

Conclusions

The P2 plans showed better agreement between planned and delivered doses compared to the P1 plans. The GPR and the plans' complexity depend on the anatomy region and are most important for the chest region.

Ophthalmologic findings and complications before and after hematopoietic stem cell transplantation: single-center study

PURPOSE

Different and various system complications and late effects may occur after hematopoietic stem cell transplantation (HSCT). It was aimed to obtain information about the frequency of ophthalmologic complications and their relationship with treatment.

METHODS

This retrospective study includes 104 children who underwent HSCT between February 2019 and June 2020 at the Pediatric Bone Marrow Transplant Unit. Patients' ages, genders, diagnosis, transplant types, chemotherapy regimens, transplantation details, conditioning regimens, supportive cares, graft versus host disease (GvHD) prophylaxis, infection episodes, and ophthalmologic findings were evaluated.

RESULTS

Of the 104 patients included in the study, 38 (36.5%) were female and 66 (63.5%) were male. Average age ± SD was 8.7 ± 4.91. Considering the diagnoses, the majority of the patients were acute lymphoblastic leukemia (46 patients-44%). Myeloablative regimen was used in 93 (89%) of the patients, and reduced intensity conditioning (RIC) was used in 11 patients (10%). While total body irradiation was applied in 16 (15%) patients, one patient was received cranial radiotherapy. Cyclosporine was used in 96 (92%) patients. CMV reactivation was detected in 54 (51%) of the patients. CMV retinitis was not seen. Ocular pathology was detected in 20 (19%) patients before HSCT and in 12 (11%) patients after HSCT. The most common pathology was dry eye.

CONCLUSION

Routine ophthalmologic examinations are important in terms of early diagnosis. In addition, GvHD and CMV prophylaxis is important because of reducing the risk of ocular complications after HSCT.

Evaluation of three VMAT-TMI planning methods to find an appropriate balance between plan complexity and the resulting dose distribution

PURPOSE

Evaluation of different planning methods of treatment plan preparation for volumetric modulated arc therapy during total marrow irradiation (VMAT-TMI).

METHOD

Three different planning methods were evaluated to establish the most appropriate VMAT-TMI technique, based on organ at risk (OAR) dose reduction, conformity and plan simplicity. The methods were: (M1) the sub-plan method, (M2) use of eight arcs optimised simultaneously and (M3) M2 with monitor unit reduction. Friedman ANOVA comparison, with Nemenyi's procedures, was used in the statistical analysis of the results.

RESULTS

The dosimetric results obtained for the planning target volume and for most OARs do not differ statistically between methods. The M3 method was characterized by the lowest numbers of monitor units (3259 MU vs. 4450 MU for M1 and 4216 MU for M2) and, in general, the lowest complexity. The variability of the monitor units from control points was almost half for M3 than M1 and M2 (i.e. 0.33 MU vs. 0.61 MU for M1 and 0.58 for M2). Analysing the relationship between the dose distributions obtained for the plans and their complexity, the best result was observed for the M3 method.

CONCLUSION

The use of eight simultaneously optimised arcs with MU reduction allows to obtain VMAT-TMI plans that are characterized by the lowest complexity, with dose distributions comparable to the plans generated by other methods.

Incidence and risk factors for cataract after haematopoietic stem cell transplantation for childhood leukaemia: an LEA study

Cataract was prospectively assessed by serial slip lamp tests in 271 patients included in the Leucémie Enfants Adolescents (LEA) programme, the French cohort of childhood leukaemia survivors. All had received haematopoietic stem cell transplantation (HSCT) after total body irradiation (TBI, n = 201) or busulfan-based (n = 70) myeloablative conditioning regimen. TBI was fractionated in all but six patients. The mean duration of follow-up from HSCT was 10·3 years. Cataract was observed in 113/271 patients (41·7%); 9/113 (8·1%) needed surgery. Cumulative incidence after TBI increased over time from 30% at 5 years to 70·8% and 78% at 15 and 20 years, respectively, without any plateau thereafter. The 15-year cumulative incidence was 12·5% in the Busulfan group. A higher cumulative steroid dose appeared to be a cofactor of TBI for cataract risk, in both univariate and multivariate Cox analysis. In the multivariate analysis, cataract had an impact in two quality of life domains: 'the role limitation due to physical problems' and 'the role limitation due to emotional problems'. These data suggest that with increasing follow-up, nearly all patients who receive TBI, even when fractionated, will suffer from cataract that can impact on their quality of life and that high cumulative steroid dose is a cofactor.

Dose response for radiation cataractogenesis: a meta-regression of hematopoietic stem cell transplantation regimens

PURPOSE/OBJECTIVE(S)

To perform a meta-regression on published data and to model the 5-year probability of cataract development after hematopoietic stem cell transplantation (HSCT) with and without total body irradiation (TBI).

METHODS AND MATERIALS

Eligible studies reporting cataract incidence after HSCT with TBI were identified by a PubMed search. Seventeen publications provided complete information on radiation dose schedule, fractionation, dose rate, and actuarial cataract incidence. Chemotherapy-only regimens were included as zero radiation dose regimens. Multivariate meta-regression with a weighted generalized linear model was used to model the 5-year cataract incidence and contributory factors.

RESULTS

Data from 1386 patients in 21 series were included for analysis. TBI was administered to a total dose of 0 to 15.75 Gy with single or fractionated schedules with a dose rate of 0.04 to 0.16 Gy/min. Factors significantly associated with 5-year cataract incidence were dose, dose times dose per fraction (D•dpf), pediatric versus adult status, and the absence of an ophthalmologist as an author. Dose rate, graft versus host disease, steroid use, hyperfractionation, and number of fractions were not significant. Five-fold internal cross-validation showed a model validity of 83% ± 8%. Regression diagnostics showed no evidence of lack-of-fit and no patterns in the studentized residuals. The α/β ratio from the linear quadratic model, estimated as the ratio of the coefficients for dose and D•dpf, was 0.76 Gy (95% confidence interval [CI], 0.05-1.55). The odds ratio for pediatric patients was 2.8 (95% CI, 1.7-4.6) relative to adults.

CONCLUSIONS

Dose, D•dpf, pediatric status, and regimented follow-up care by an ophthalmologist were predictive of 5-year cataract incidence after HSCT. The low α/β ratio indicates the importance of fractionation in reducing cataracts. Dose rate effects have been observed in single institution studies but not in the combined data analyzed here. Although data were limited to articles with 5-year actuarial estimates, the development of radiation-induced cataracts extends beyond this time.

Verification of dose distribution for volumetric modulated arc therapy total marrow irradiation in a humanlike phantom

PURPOSE

Volumetric modulated arc therapy (VMAT) treatment planning studies have been reported to provide good target coverage and organs at risk (OARs) sparing in total marrow irradiation (TMI). A comprehensive dosimetric study simulating the clinical situation as close as possible is a norm in radiotherapy before a technique can be used to treat a patient. Without such a study, it would be difficult to make a reliable and safe clinical transition especially with a technique as complicated as VMAT-TMI. To this end, the dosimetric feasibility of VMAT-TMI technique in terms of treatment planning, delivery efficiency, and the most importantly three dimensional dose distribution accuracy was investigated in this study. The VMAT-TMI dose distribution inside a humanlike Rando phantom was measured and compared to the dose calculated using RapidArc especially in the field junctions and the inhomogeneous tissues including the lungs, which is the dose-limiting organ in TMI.

METHODS

Three subplans with a total of nine arcs were used to treat the planning target volume (PTV), which was determined as all the bones plus the 3 mm margin. Thermoluminescent detectors (TLDs) were placed at 39 positions throughout the phantom. The measured TLD doses were compared to the calculated plan doses. Planar dose for each arc was verified using mapcheck.

RESULTS

TLD readings demonstrated accurate dose delivery, with a median dose difference of 0.5% (range: -4.3% and 6.6%) from the calculated dose in the junctions and in the inhomogeneous medium including the lungs.

CONCLUSIONS

The results from this study suggest that RapidArc VMAT technique is dosimetrically accurate, safe, and efficient in delivering TMI within clinically acceptable time frame.

Eye shielding during total body irradiation for bone marrow transplantation in children transplanted for a hematological disorder: risks and benefits

This is a retrospective analysis of 188 children who underwent total body irradiation (TBI) in one or two fractions before bone marrow transplantation (BMT) for a hematological disorder. While 139 children had eye shielding during TBI to decrease cataract formation, 49 did not. The blocks used for shielding caused cylindrical areas of decreased dose intensity in the brain. The aim of the study was to determine if there was an increased risk of relapse in the eyes or in the CNS after shielding of the eyes. The probability and severity of cataract formation with and without shielding were also evaluated. None of the 49 children without shielding had a relapse in their eyes or in the CNS after BMT. Of the children with shielding, none had a relapse in the eyes but two of the 139 (1.4%) had a CNS relapse. The incidence of cataracts without shielding was 90% (19 of 21 evaluable patients), while with shielding it was 31% (20 of 64). Severe cataracts were present in eight of 21 (38%) patients without and two of 64 (3%) patients with shielding. The probability of staying cataract free for at least five years was 0.77 with and 0.33 without shielding, at 8 years it was 0.53 and 0.24 respectively. The relative risk of developing a cataract without shielding vs shielding was three (95% CI=1.5; 5.9). It appears that the incidence of relapse in the eyes and CNS is not increased when the eyes are shielded during TBI. Shielding increased the latency time of cataract formation and decreased the severity of cataracts.

New approaches to hematopoietic cell transplantation in oncology

The use of high-dose chemotherapy followed by autologous HCT and the use of allogeneic HCT in children and adolescents with high-risk ALL, AML, and NBL has successfully improved outcomes. For other diseases, however, the role of HCT in treatment remains a subject of further research. The availability of HCT was significantly expanded by developing alternative graft sources that currently include BM, peripheral blood, and UCB from autologous and allogeneic related or unrelated donors. Progress in autologous HCT has been achieved by the identification of more effective and less toxic preparative regimens and by ex vivo purging of stem cell products. In allogeneic HCT, graft-versus-leukemia or graft-versus-tumor effects are being exploited increasingly to lower relapse rates. In addition, immunomodulation to promote tolerance, as well as allogeneic antitumor reactions have been achieved by antibody therapy, cytokine therapy, or cell-based immunotherapy. Future improvements are likely, as evidenced by promising preliminary results in the development of stem cell collection techniques, in vitro stem cell expansion, and purging techniques of stem cell grafts. The development of less intensive or nonmyeloablative preparative regimens may further reduce regimen-related morbidity and mortality Specific immunotherapy may facilitate tolerance induction in mismatched allogeneic HCT and support allogeneic HCT in the setting of donor-host HLA disparity. Ultimately, advances in cytokine therapy, tumor-specific vaccines, and gene therapy may decrease or even eradicate recurrence of the malignant disease after HCT.