A systematic review of craniospinal irradiation for leptomeningeal disease: past, present, and future

Purpose Leptomeningeal disease (LMD) is a rare but deadly complication of cancer in which the disease spreads to the cerebrospinal fluid and seeds the meninges of the central nervous system (CNS). Craniospinal irradiation (CSI) involves treatment of the entire CNS subarachnoid space and is occasionally used as a last-resort palliative therapy for LMD. Methods This review examined literature describing the role of CSI for LMD from solid and hematologic malignancies in adults. A search for studies published until September 1, 2020 was conducted using PubMed database. Results A total of 262 unique articles were identified. Thirteen studies were included for analysis in which a total of 275 patients were treated with CSI for LMD. Median age at time of irradiation was 43 years, and most patients had KPS score of 70 and higher. The most common cancers resulting in LMD were acute lymphocytic leukemia, breast cancer, and acute myelogenous leukemia. Median CSI dose was 30 Gy and 18% of patients were treated with proton radiation. 52% of patients had stable-to-improved neurologic symptoms. Median overall survival for the entire cohort was 5.3 months. Patients treated with marrow-sparing proton radiation had median OS of 8 months. The most common treatment toxicities were hematologic and gastrointestinal events. Conclusions Despite advances in systemic and radiation therapies, LMD remains a devastating end-stage complication of some malignancies. Treatment-related toxicities can be a significant barrier to CSI delivery. In select patients with LMD, marrow-sparing proton CSI may provide safer palliation of symptoms and prolong survival (AU)

Late effects of craniospinal irradiation for medulloblastomas in paediatric patients.

Along with surgery, radiation therapy (RT) remains an essential option to cure patients suffering from medulloblastoma. However, its long-term adverse effects, particularly due to craniospinal irradiation (CSI), which is necessary to eradicate microscopic spread, are a limiting factor. The most frequent sequelae involve neurocognitive and endocrine impairment, which occurs in nearly all patients. Recent progress achieved through genetic and molecular biology offers the possibility to better stratify patients according to risk factors such as age, post-resection tumour residue and metastasis. Thus, new therapeutic studies assess the possibility to reduce radiation dose and/or radiation field size for patients with the most favourable prognosis. New radiotherapy techniques are also used such as Intensity-Modulated Radiotherapy (IMRT), tomotherapy and proton therapy, which aim at reducing the dose delivered to normal tissue. Conventional photon-based therapy has a relatively high exit dose in contrast with proton therapy which causes less damage to surrounding healthy tissue. It is noteworthy that each technique requires a long follow-up in order to prove that late effects could be reduced without compromising survival rates. Dosimetric comparison theoretically suggests that proton therapy may be the superior method for CSI in terms of late effects, but further research is needed to firmly establish this. Whatever the technique used, the great complexity of CSI requires discipline and expertise along with an external quality control online before the first RT session.

Optimization of Intracranial Germinoma Treatment: Radiotherapy Alone with Reduced Volume and Dose.

PURPOSE: We investigated optimal management for intracranial germinoma, including target volume and dose of radiation therapy (RT) and the combination of RT and chemotherapy (CTx). METHODS AND MATERIALS: We retrospectively evaluated 213 patients with intracranial germinoma treated between 1971 and 2017. Treatment policies changed as diagnostic techniques and clinical experience improved. In the 1980s, trial RT and tumor marker study were performed, and craniospinal irradiation was performed to treat patients with presumed germinoma. CTx was introduced in 1991, and RT volume was reduced in patients showing a complete response. In 2012, the policy was changed to a "reduced volume/dose RT alone" approach, involving a smaller target volume (the whole ventricle/whole brain for localized disease) without CTx. RT doses were gradually reduced to 36 Gy for primary tumors and 18 Gy for neuraxis. RESULTS: The median age was 16 years. In total, 118 and 95 patients had pathologically proven and presumed germinoma, respectively, and 151 and 62 patients had localized and multifocal or metastatic diseases, respectively. With a median follow-up of 141 months, the 10-year disease-free and overall survival rates were 91.6% and 95.6%, respectively. Recurrence rates were similar for patients receiving RT-only (9 of 137, 6.6%) and those receiving CTx + RT (4 of 73, 5.5%); all patients receiving CTx-only experienced recurrences (3 of 3, 100%). Rates were the highest in the focal RT group (10 of 29, 34.5%) but were relatively low in the whole ventricle/whole brain RT (3 of 51, 5.9%) and craniospinal irradiation groups (0 of 130, 0%). Infield failure occurred in 3 patients. Fourteen patients died of recurrence (n = 4), secondary malignancy (n = 4), CTx-related toxicity (n = 2), and others (n = 4). Among the 33 patients who received "reduced volume/dose RT alone" treatment, 2 (6.1%) experienced recurrence in the spinal cord and biopsy tract, respectively. CONCLUSIONS: The additional benefit of CTx in the treatment of intracranial germinoma seems minimal. An RT-only approach with reduced target volume and dose seems reasonable.

Is there an increased risk of spinal relapse in standard-risk medulloblastoma/primitive neuroectodermal tumor patients who receive only a reduced dose of craniospinal radiotherapy?

PURPOSE: Medulloblastoma (MBL) is the most common pediatric brain malignancy. Postoperative radiotherapy to the entire craniospinal axis is the standard-of-care but has linked to long-term morbidity. In this study, we analyzed the implication of reduced dose craniospinal radiotherapy (RT) for survival and pattern of relapse in MBL patients. MATERIAL AND METHODS: The clinical characteristics of 32 consecutively diagnosed medulloblastoma/primitive neuroectodermal tumor patients were analyzed. After surgical resection, a dose of 23.4 Gy of spinal RT with a posterior fossa boost of 30.6 Gy was prescribed to standard-risk patients, whereas high-risk patients received 36 Gy spinal RT with additional boosts to the posterior fossa up to 54 Gy. Then, both groups received the same chemotherapy protocol. RESULTS: Five-year OS for standard and high-risk patients was 94 and 50%, respectively. When analyzing prognostic factors, postoperative tumor size is the most important one which affects the OS. Ten patients relapsed during follow-up, and there was no isolated spinal relapse in either group. CONCLUSION: The risk of isolated spinal relapse does not increase with reduced-dose craniospinal RT, since there is no isolated relapse in either the standard or high-risk groups of patients.

Vulnerability of white matter to insult during childhood: evidence from patients treated for medulloblastoma.

OBJECTIVE Craniospinal irradiation damages the white matter in children treated for medulloblastoma, but the treatment-intensity effects are unclear. In a cross-sectional retrospective study, the effects of treatment with the least intensive radiation protocol versus protocols that delivered more radiation to the brain, in addition to the effects of continuous radiation dose, on white matter architecture were evaluated. METHODS Diffusion tensor imaging was used to assess fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity. First, regional white matter analyses and tract-based spatial statistics were conducted in 34 medulloblastoma patients and 38 healthy controls. Patients were stratified according to those treated with 1) the least intensive radiation protocol, specifically reduced-dose craniospinal irradiation plus a boost to the tumor bed only (n = 17), or 2) any other dose and boost combination that delivered more radiation to the brain, which was also termed the "all-other-treatments" group (n = 17), and comprised patients treated with standard-dose craniospinal irradiation plus a posterior fossa boost, standard-dose craniospinal irradiation plus a tumor bed boost, or reduced-dose craniospinal irradiation plus a posterior fossa boost. Second, voxel-wise dose-distribution analyses were conducted on a separate cohort of medulloblastoma patients (n = 15). RESULTS The all-other-treatments group, but not the reduced-dose craniospinal irradiation plus tumor bed group, had lower fractional anisotropy and higher radial diffusivity than controls in all brain regions (all p < 0.05). The reduced-dose craniospinal irradiation plus tumor bed boost group had higher fractional anisotropy (p = 0.05) and lower radial diffusivity (p = 0.04) in the temporal region, and higher fractional anisotropy in the frontal region (p = 0.04), than the all-other-treatments group. Linear mixed-effects modeling revealed that the dose and age at diagnosis together 1) better predicted fractional anisotropy in the temporal region than models with either alone (p < 0.005), but 2) did not better predict fractional anisotropy in comparison with dose alone in the occipital region (p > 0.05). CONCLUSIONS Together, the results show that white matter damage has a clear association with increasing radiation dose, and that treatment with reduced-dose craniospinal irradiation plus tumor bed boost appears to preserve white matter in some brain regions.