Hematological toxicity after robotic stereotactic body radiosurgery for treatment of metastatic gynecologic malignancies.

PURPOSE: To evaluate hematological toxicity after robotic stereotactic body radiosurgery (SBRT) for treatment of women with metastatic abdominopelvic gynecologic malignancies. METHODS AND MATERIALS: A total of 61 women with stage IV gynecologic malignancies treated with abdominopelvic SBRT were analyzed after ablative radiation (2400 cGy/3 divided consecutive daily doses) delivered by a robotic-armed Cyberknife SBRT system. Abdominopelvic bone marrow was identified using computed tomography-guided contouring. Fatigue and hematologic toxicities were graded by retrospective assignment of common toxicity criteria for adverse events (version 4.0). Bone marrow volume receiving 1000 cGy (V10) was tested for association with post-therapy (median 32 days [25%-75% quartile, 28-45 days]) white- or red-cell counts, hemoglobin levels, and platelet counts as marrow toxicity surrogates. RESULTS: In all, 61 women undergoing abdominopelvic SBRT had a median bone marrow V10 of 2% (25%-75% quartile: 0%-8%). Fifty-seven (93%) of 61 women had received at least 1 pre-SBRT marrow-taxing chemotherapy regimen for metastatic disease. Bone marrow V10 did not associate with hematological adverse events. In all, 15 grade 2 (25%) and 2 grade 3 (3%) fatigue symptoms were self-reported among the 61 women within the first 10 days post-therapy, with fatigue resolved spontaneously in all 17 women by 30 days post-therapy. Neutropenia was not observed. Three (5%) women had a grade 1 drop in hemoglobin level to <10.0 g/dL. Single grade 1, 2, and 3 thrombocytopenias were documented in 3 women. CONCLUSIONS: Abdominopelvic SBRT provided ablative radiation dose to cancer targets without increased bone marrow toxicity. Abdominopelvic SBRT for metastatic gynecologic malignancies warrants further study.

18FDG-PET/CT Definition of Clinical Target Volume for Robotic Stereotactic Body Radiosurgery Treatment of Metastatic Gynecologic Malignancies.

The objective of the current article was to evaluate 2-[18F]fluoro-2-deoxy-D-glucose 18F-FDG) as measured by positron emission tomography for delineation of abdominopelvic gross tumor volumes (GTV) for stereotactic body radiosurgery treatment (SBRT) of metastatic gynecologic cancers. A retrospective review of SBRT was conducted in 27 women with stage IV gynecologic cancers recurring in para-aortic lymph nodes. Robotic SBRT involved 2400 cGy in 3 consecutive 800 cGy daily fractions prescribed to a 3.0 mm expanded planning tumor volume (PTV) defined by both CT-based and 18F-FDG-based GTVs. In this study, 18F-FDG-based GTVs led to significantly larger PTVs in all 27 women, than if they had been based on CT GTVs alone (P < 0.001). Enlarged PTVs may have resulted from the breathing-induced target motion during the time of 18F-FDG image acquisition smearing 18F-FDG signal over a greater anatomic dimension. Ultimately, SBRT-target local control, based on the RECIST 1.1 criteria, was 96% (26 of 27), and associated with minor reversible toxicity. The use of 18F-FDG to define SBRT target volumes warrants further interrogation in SBRT clinical trials.

Comparison of helical tomotherapy versus conventional radiation to deliver craniospinal radiation.

The purpose of this study was to investigate whether helical tomotherapy would better dose-limit growing vertebral ring apophyses during craniospinal radiation as compared to conventional techniques. Four pediatric patients with M0 medulloblastoma received tomotherapy craniospinal radiation (23.4 Gy, 1.8 Gy/fx) by continuous helical delivery of 6 MV photons. Weekly blood counts were monitored. For comparison, conventional craniospinal radiation plans were generated. To assist in tomotherapy planning, a cross-sectional growth study of 52 children and young adults was completed to evaluate spine growth and maturation. Vertebral ring apophyses first fused along the posterolateral body-pedicle synostosis, proceeding circumferentially toward the anterior vertebral body such that the cervical and lumbar vertebrae fused early and mid-thoracic vertebrae fused late. For the four pediatric patients, tomotherapy resulted between 2% and 14% vertebral volume exceeding 23 Gy. Conventional craniospinal radiation predicted between 33% and 44% exceeding 23 Gy. Cumulative body radiation doses exceeding 4 Gy were between 50% and 57% for tomotherapy and between 25% and 37% for conventional craniospinal radiation. Tomotherapy radiation reduced neutrophil, platelet, and erythrocyte hemoglobin levels during treatment. Tomotherapy provides improved dose avoidance to growing vertebrae as compared to conventional craniospinal radiation. However, the long-term effects of tomotherapy dose avoidance on spine growth and large volume low dose radiation in children are not yet known.