Early clinical experience and outcome of helical tomotherapy for multiple metastatic lesions.

PURPOSE To evaluate the feasibility of synchronous treatment of multiple metastatic lesions by helical tomotherapy. METHODS AND MATERIALS Forty-two patients with multiple metastatic lesions were treated by helical tomotherapy from April 2006 to February 2007. Among these patients, 21 had metastatic bone disease. Subjective pain response was assessed using the visual analogue scales, and morbidity was evaluated by Common Terminology Criteria for Adverse Events v3.0. The correlation between the percentage of red bone marrow in the radiation field and the severity of leukocytopenia was analyzed. RESULTS The median age was 57 years. Radiation dose to the gross tumor volume was 30-84 Gy, with a median fractional size of 3 Gy. Mean treatment time was 16 min and 1 sec. Treatment time and fraction size were modified because of poor performance status or hematologic toxicity in two patients. With regard to palliative effects for bone metastasis, 16 patients (76.2%) experienced positive pain relief. Four patients had Grade III leukocytopenia, and three had Grade IV leukocytopenia. In the multivariate logistic regression, red marrow percentage was the independent risk factor most associated with Grade III/IV leukocytopenia (p = 0.014). The tolerance cutoff point of red bone marrow was 26.8%, with a sensitivity and specificity of 85.7% and 85.7%, respectively. CONCLUSIONS Helical tomotherapy was effective for symptom palliation and was feasible for patients with multiple metastatic diseases. The volume of red bone marrow, as well as performance status, must be taken into account to determine optimal treatment.