Outcome and toxicity using helical tomotherapy for craniospinal irradiation in pediatric medulloblastoma

The objective of this study is to evaluate the tolerability and outcome of craniospinal irradiation (CSI) with helical tomotherapy (HT) in the treatment of medulloblastoma.

We evaluated 19 consecutive patients with primary medulloblastoma who were treated with HT from 2007 through 2010. HT regimens to the neuroaxis included: 23.4 Gy at 1.8 Gy/fraction (N = 10), 36 Gy at 1.8 Gy/fraction (N = 7), and 39 Gy bid at 1.3 Gy/fraction (N = 2). The tumor bed received 54-60 Gy. Potential associations between patient, treatment, and toxicity factors and overall survival (OS) were assessed in univariate analyses using the Cox proportional hazards model. Spearman's rank correlation coefficient was used to correlate potential risk factors with the grade of acute toxicity.

The median age at diagnosis was 5 years (range 2-14) and the median follow-up for alive patients (N = 14) 40 months (range 10-62). Two- and three-year overall survival was 75 and 68 %, respectively. The most common acute toxicity was hematological (79 %), being grade 2 and grade 3 in 4 (21 %) and 11 (58 %) cases, respectively. No grade ≥2 late toxicities were observed. Higher grades of acute body toxicity were found in older children (P = 0.004). Longer time between diagnosis and radiation therapy was correlated with shorter OS (P = 0.03). In addition, higher grades of acute thrombocytopenia were associated with shorter OS (P = 0.03).

CSI delivered with HT for medulloblastoma is well tolerated with low rates of severe acute toxicity. Further research is necessary to assess late toxicity with a longer follow-up.