[Reduced acute toxicity for adults with medulloblastoma treated with proton beam craniospinal irradiation]

Medulloblastoma in adults : A retrospective single institution analysis

PURPOSE

Adult medulloblastoma is a rare disease treated according to the current pediatric treatment guidelines. This retrospective analysis investigated the clinical outcomes and prognostic factors of adult medulloblastoma patients, who received multimodal therapy at our institution.

METHODS

Treatment charts of all patients over the age of 15 years of age with de novo medulloblastoma, who had been treated at our institution between 2001 and 2014, were retrospectively analyzed. Patients' demographic parameters, initial symptoms, treatment modalities, toxicities, and survival outcomes were investigated.

RESULTS

In all, 21 patients with a median age of 30.2 years were identified. The most frequent histologies were desmoplastic and classic, and the most common molecular subtype was sonic hedgehog (SHH). After tumor resection, all patients received craniospinal irradiation (median dose 35.2 Gy) and a boost to the posterior fossa (median dose 19.8 Gy). Simultaneous chemotherapy with vincristine was given to 20 patients and sequential chemotherapy to 15 patients. The most common side effects were hematological toxicities. Median overall survival (OS) has not been reached after a median follow-up of 92 months. Estimated 5‑ and 10-year OS was 89 and 80%, respectively. Estimated 5‑ and 10-year progression-free survival (PFS) was 89 and 81%, respectively. In univariate analysis, a shorter interval between tumor resection and end of irradiation was significantly associated with improved OS and PFS, anaplastic histology with worse OS and PFS.

CONCLUSIONS

The combined modality treatment showed a good outcome in adults with medulloblastoma. Treatment time was revealed to be prognostic and should be kept as short as possible.

Impact of radiation technique, radiation fraction dose, and total cisplatin dose on hearing : Retrospective analysis of 29 medulloblastoma patients

PURPOSE

To analyze the incidence and degree of sensorineural hearing loss (SNHL) resulting from different radiation techniques, fractionation dose, mean cochlear radiation dose (D_mean), and total cisplatin dose.

MATERIAL AND METHODS

In all, 29 children with medulloblastoma (58 ears) with subclinical pretreatment hearing thresholds participated. Radiotherapy (RT) and cisplatin had been applied sequentially according to the HIT MED Guidance. Audiological outcomes up to the latest follow-up (median 2.6 years) were compared.

RESULTS

Bilateral high-frequency SNHL was observed in 26 patients (90%). No significant differences were found in mean hearing threshold between left and right ears at any frequency. A significantly better audiological outcome (p < 0.05) was found after tomotherapy at the 6 kHz bone-conduction threshold (BCT) and left-sided 8 kHz air-conduction threshold (ACT) than after a combined radiotherapy technique (CT). Fraction dose was not found to have any impact on the incidence, degree, and time-to-onset of SNHL. Patients treated with CT had a greater risk of SNHL at high frequencies than tomotherapy patients even though D_mean was similar. Increase in severity of SNHL was seen when the total cisplatin dose reached above 210 mg/m², with the highest abnormal level found 8-12 months after RT regardless of radiation technique or fraction dose.

CONCLUSION

The cochlear radiation dose should be kept as low as possible in patients who receive simultaneous cisplatin-based chemotherapy. The risk of clinically relevant HL was shown when D_mean exceeds 45 Gy independent of radiation technique or radiation regime. Cisplatin ototoxicity was shown to have a dose-dependent effect on bilateral SNHL, which was more pronounced in higher frequencies.