RT-25 * NAUSEA AND EMESIS IN MEDULLOBLASTOMA PATIENTS TREATED WITH PROTON RADIOTHERAPY

Abstract

OBJECTIVE: Nausea and emesis are common during craniospinal irradia- tion (CSI) for medulloblastoma. The etiology of these side effects is unclear as photon CSI delivers radiation to the brain and gastrointestinal (GI) tract. Proton CSI delivers a similar radiation dose to the brain yet minimal radiation to theGItract, providingan opportunity to compare these twopathways. This study reports the incidence and severity of nausea and emesis associated with proton therapy (PT) for children with medulloblastoma. METHODS: Between December 2007 and February 2013, 33 children (45% girls; 55% boys) received proton therapy (CSI, n ¼ 29; focal, n ¼ 4) for medulloblasto- ma. Median age was 6.5 years (range, 1.4-21.1). 70% were standard risk. All received chemotherapy(76%concurrent). Patients were not routinely pre- medicated with antiemetics. Serial weight measurements and data on nausea and emesis were prospectively collected weekly during PT and at each follow-up using CTCAE. Maximum grade toxicity was recorded. Clinical and dosimetric factors were analyzed using Fisher’s exact test. RESULTS: Medianfollow-upwas2.6 years (range,0 .1 to 5.7). Three patients(9%)devel- oped grade 3 nausea and/or emesis during PT; 21% and 12% experienced grade 2 nausea and emesis, respectively. No patients developed grade 4+ nausea or emesis. Median total weight change during PT was -6.5% (range, -16%-+14.1%);57%of patients lost≥5%of their body weight during treat- ment and20%lost ≥10%. Neither age nor dose was associated with toxicity. Grade 2+emesis was observed in girls more often than boys (33.3% vs 5.6%; p ¼ 0.07). One patient had grade 2 emesis continue after PT, which subse- quently resolved. Otherwise, no grade 2+nausea or emesis followed the com- pletion of PT.CONCLUSION:Given the absence of significant dose to the GI tract with proton CSI, these data suggest that ,10% of serious toxicity is at- tributable to emetogenic centers in the brain.