The purpose of this study is to evaluate the efficacy of hypofractionated stereotactic radiation treatments (SBRT) on children, teenagers and young adults malignant tumors.

SBRT (Stereotactic Body Radiation Therapy) is a radiotherapy treatment which involves the delivery of a single high dose radiation treatment or a few fractionated radiation treatments (usually up to 5). A high potent biological dose of radiation is delivered to the tumor improving the cure rates for the tumor, in a manner previously not achievable by standard conventional radiation therapy.

For adult patients, the "Haute Authorité de Santé" (HAS) validates some indications for this treatment which are the followings :

• Few primary or secondary brain tumors, which cannot be surgically removed
• Spinal tumors
• Primary bronchopulmonary tumors T1 T2 N0 M0 and pulmonary metastasis with slow growth and controled primary tumor.

For pediatrics patients, no indication is now validated by HAS. Indications validated for adults are rare in pediatrics but not exceptional, and in such cases efficient alternative treatments does not exist.

In consequence, and regarding the good results obtained in adult patients, it seems very important to validate the efficacy of this treatment on pediatrics population

INCLUSION CRITERIA:

• 18 months ≤ age ≤ 20 years

• Malignant primary tumor, histologically or cytologically proven

• Systemic disease under control or with slow evolution

• Written indication of SBRT according to local pediatrics meeting and national Radiotherapy (RT) web conference

• Performance Status ≤ 2 according to Eastern Cooperative Oncology Group (ECOG)

• Sites

  • Brain metastasis (≤ 3 on MRI) not suitable for surgery, without hemorrhage, less than 3 cm each, not in the brain stem
  • Primary or secondary spinal/para spinal metastasis (≤ 3), not suitable for surgery or with a non operable macroscopic residue, less than 5 cm
  • Lung metastasis (≤ 3), less than 5 cm, not eligible for surgery, or macroscopic residue not suitable for surgery
  • Previously irradiated relapsing isolated primitive/secondary tumor (intra cranial or extra cranial), with no possible surgery, or macroscopic residue.

• Affiliation to a social security scheme

• Signed Informed consent by patient or parents and patient

IN ADDITION FOR RELAPSING EPENDYMOMA:

• Histologically proven local ependymoma at diagnosis
• Previously irradiated ependymoma
• Exclusive local relapse in previously irradiated site
• Review of operability at time of relapse by a multidisciplinary staff
• Relapse must be confirmed by a neuro-oncology multidisciplinary staff, on MRI evolutivity characteristics
• Time to relapse after previous irradiation ≥ 1 year

NON-INCLUSION CRITERIA :

• Concomitant chemotherapy
• No evaluable target (except for completely resected ependymomas)
• Pregnancy
• Follow-up impossible

IN ADDITION FOR RELAPSING EPENDYMOMAS:

• Metastatic patient at diagnosis and/or at relapse
• Complete remission never obtained

NON-RANDOMIZATION DOSIMETRIC CRITERIA (ONLY FOR EPENDYMOMA)

• Cumulative doses to brain stem ≥ 115 Gy
• Tumor volume at relapse ≥ 30 cm3
• Primary RT dose + Re-irradiation dose more than 112 Gy
• Cumulative dose to the chiasma > 54 Gy
• Cumulative dose to any point of the brain > 115 Gy