Total marrow irradiation as part of autologous stem cell transplantation for Asian patients with multiple myeloma

Total marrow irradiation in hematopoietic stem cell transplantation for hematologic malignancies

Total body irradiation (TBI) has been an essential component of the conditioning regimen in hematopoietic cell transplantation for many years. However, higher doses of TBI reduce disease relapse at the expense of more significant toxicities. Therefore, total marrow irradiation and total marrow and lymphoid irradiation have been developed to deliver organ-sparing targeted radiotherapy. Data from different studies show that TMI and TMLI can be safely administered in escalating doses in association with different chemotherapy conditioning regimen protocols, in situations with unmet needs, such as multiple myeloma, high-risk hematologic malignancies, relapsed or refractory leukemias, and elderly or frail patients, with low rates of transplant-related mortality. We reviewed the literature on applying TMI and TMLI techniques in autologous and allogeneic hematopoietic stem cell transplantation in different clinical situations.

The safety and efficacy of a novel hypo-fractionated total marrow and lymphoid irradiation before allogeneic stem cell transplantation for lymphoma and acute leukemia

Purpose

Total body irradiation (TBI) has been widely utilized as part of the conditioning regimen for hematopoietic stem cell transplantation (HSCT), but is associated with significant toxicities. Targeted TBI using helical Tomotherapy allows precise and homogeneous tumor coverage and excellent sparing of organs at risk. The purpose of this study was to evaluate the clinical outcomes of a novel hypo-fractionation strategy for patients receiving total marrow and involved lymphoid irradiation (TMLI) as part of the conditioning regimen before HSCT.

Methods and Materials

61 patients (7 acute myelogenous leukemia (AML), 33 acute lymphoblastic leukemia (ALL), 18 non-Hodgkin's lymphoma (NHL), 3 mixed acute leukemia (MAL)) received conditioning radiation treatment with TMLI (8 Gy to bone marrow, 10 Gy to involved field in 2 fractions per day) in conjunction with chemotherapy before transplantation.

Results

The median age of 61 patients with TMLI was 24 (4-54) years. The prescribed dose covered the entire bone and involved target volume, and the dose of organs at risk (OAR) was reduced by 28%-78% of the prescription dose. Grade 1-2 nausea and vomiting occurred in 12 patients and grade 1-2 pain in 6 patients during radiotherapy. Fatigue occurred in 16 patients. 2 patients had diarrhea, enteritis, and 1 patient had fever. None of patient had grade 3-4 non-hematologic adverse reactions. Late (30 days after HSCT) grade 2 toxicities including reversible enteritis occurred in 3 patients. 5 patients developed infectious pneumonia. The 2 years progression-free survival (PFS) was 64.1% (95% CI: 0.16-0.22) and overall survival (OS) was 74.7% (95% CI: 0.19-0.24) for the 61 patients who had received their planned HSCT. The 2-year non-relapse mortality was significantly reduced to 5% in this patient cohort.

Conclusions

This study demonstrates that hypo-fractionated TMLI (8 Gy to bone marrow, 10 Gy to involved field in a single day) as a conditioning regimen for lymphoma and acute leukemia was feasible and the clinical outcomes were acceptable.

Total marrow and lymphoid irradiation with helical tomotherapy: a practical implementation report

Purpose

To standardize the technique; evaluate resources requirements and analyze our early experience of total marrow and lymphoid irradiation (TMLI) as part of the conditioning regimen before allogenic bone marrow transplantation using helical tomotherapy.

Materials and Methods

Computed tomography (CT) scanning and treatment were performed in head first supine (HFS) and feet first supine (FFS) orientations with an overlap at mid-thigh. Patients along with the immobilization device were manually rotated by 180° to change the orientation after the delivery of HFS plan. The dose at the junction was contributed by a complementary dose gradient from each of the plans. Plan was to deliver 95% of 12 Gy to 98% of clinical target volume with dose heterogeneity <10% and pre-specified organs-at-risk dose constraints. Megavoltage-CT was used for position verification before each fraction. Patient specific quality assurance and in vivo film dosimetry to verify junction dose were performed in all patients.

Results

Treatment was delivered in two daily fractions of 2 Gy each for 3 days with at least 8-hour gap between each fraction. The target coverage goals were met in all the patients. The average person-hours per patient were 16.5, 21.5, and 25.75 for radiation oncologist, radiation therapist, and medical physicist, respectively. Average in-room time per patient was 9.25 hours with an average beam-on time of 3.32 hours for all the 6 fractions.

Conclusion

This report comprehensively describes technique and resource requirements for TMLI and would serve as a practical guide for departments keen to start this service. Despite being time and labor intensive, it can be implemented safely and robustly.