Brain tumors cannot always be reliably removed without leaving microscopic residual tumor tissue. Furthermore, there are tumor localizations that make surgical therapy impossible.
The goal of radiation therapy in such cases is:
- To prevent residual tumor tissue from further growth.
- Treatment of a tumor that cannot be treated surgically because of its location
Three concepts are distinguished based on the irradiation fields (target volumes):
- Radiotherapy of the extended tumor region (due topossible residual tumor tissue).
- Radiotherapy of the whole head also including the meninges (meninges).
- Radiotherapy of the entire cerebrospinal fluid space (synonym: neuroaxis/craniospinal axis).
Ad 1. Local treatment (to treat the extended tumor region):
- Ependymoma without cerebrospinal fluid connection
- Low and high malignant gliomas
- Optic glioma craniopharyngeoma
- Supratentorial tumors
Ad 2. radiotherapy of the whole head (whole brain irradiation).
- Brain metastases,
- Preventive treatment “malignant systemic diseases” (lymphoblastic leukemias).
Ad 3. radiotherapy of the entire cerebrospinal fluid space.
- Infratentorial tumors:
- Ependymoma
- Medulloblastoma
- Supratentorial tumors connected to the cerebrospinal fluid system:
- Ependymoma
- Pineal tumors (germ cell tumors, pinealoblastoma).
- PNET (primitive neuroectodermal tumor).
Irradiation procedure:
- Stereotactic conformational irradiation (allows for customization of irregularly shaped tumors through three-dimensional conformational irradiation).
- Stereotactic single time irradiation / linear accelerator-based systems or.
- Gamma-Knife (stereotactic single time treatment; advantage: application of sufficient dose within the tumor excluding co-irradiation of healthy/normal surrounding brain tissue.
- Indications:
- Vascular malformations
- Benign tumors originating from the auditory nerve (acoustic neuromas).
- Brain metastases (no more than three foci); patients with no more than three brain metastases from breast cancer (mammary carcinoma) or non-small cell lung or bronchial carcinoma (NSCLC), survived longer with stereotactic radiosurgery than with whole-brain radiotherapy
Further notes
- Proton therapy probably achieves cure in children with medulloblastoma with the same frequency as radiotherapy with photons.In the present study, the the tumor was partially or completely removed by surgery. Subsequently, all patients received chemotherapy and craniospinal proton irradiation (dose 23.4 biological Gray equivalent, GyRBE, plus a median boost irradiation of 54.0 GyRBE). Progression-free survival at 5 years was 85% (95 percent confidence interval: 69-93 percent) for standard-risk patients and 70% (45-85%) for intermediate- to high-risk patients. This is consistent with the results achieved with current standard treatment including “photon” therapy. An advantage of proton therapy may be the lack of late cardiac, pulmonary, and gastrointestinal (GI) sequelae. Further studies are to be awaited.
- Radiochemotherapy (RCTX) after surgery in aged glioblastoma patients: progression-free survival increased from 3.9 to 5.3 months and overall survival from 7.6 to 9.3 months.
- Patients with brain metastases experience less cognitive impairment after stereotactic irradiation of the resection cavity than after resection and whole brain irradiation; survival was almost equal in both groups (11.6 months versus 12.2 months).
