A method for reducing ovarian doses in whole neuro-axis irradiation for medulloblastoma

Molecular Mechanism and Prevention Strategy of Chemotherapy- and Radiotherapy-Induced Ovarian Damage

Fertility preservation is an emerging discipline, which is of substantial clinical value in the care of young patients with cancer. Chemotherapy and radiation may induce ovarian damage in prepubertal girls and young women. Although many studies have explored the mechanisms implicated in ovarian toxicity during cancer treatment, its molecular pathophysiology is not fully understood. Chemotherapy may accelerate follicular apoptosis and follicle reservoir utilization and damage the ovarian stroma via multiple molecular reactions. Oxidative stress and the radiosensitivity of oocytes are the main causes of gonadal damage after radiation treatment. Fertility preservation options can be differentiated by patient age, desire for conception, treatment regimen, socioeconomic status, and treatment duration. This review will help highlight the importance of multidisciplinary oncofertility strategies for providing high-quality care to young female cancer patients.

MRI-guided definition of cerebrospinal fluid distribution around cranial and sacral nerves: implications for brain tumors and craniospinal irradiation

Background: The SIOPE-Brain Tumor Group recently published a guideline on craniospinal target volume delineation for highly conformal radiotherapy. In order to spare critical structures like e.g., the lens or cochlea, highly conformal techniques can underdose the cerebrospinal fluid (CSF) in the dural reflections around cranial and sacral nerves. The purpose of this study is to generate evidence for CSF extension within the dural sheaths of the cranial and sacral nerves in order to improve accuracy in target volume delineation.Material and methods: Ten healthy volunteers, age 21 till 41 years, underwent an MRI-scan of the skull-base and sacral plexus. To evaluate CSF extension, cT2-weighted images with fat suppression, low signal to noise ratio and little to no motion-related artifacts were used. Two observers measured the extension of CSF from the inner table of the skull for the cranial nerves, and outside the spinal canal for the sacral nerves.Results: CSF extension (mean distance [95% CI]) was visible within the dural sheaths surrounding the majority of the cranial nerves: optic nerve (40 mm [38-42]), trigeminal nerve (16 mm [15-19]), facial-vestibulocochlear nerve (11 mm [11-12]), glossopharyngeal-vagus-accessory nerve (7 mm [7-9]) and hypoglossal nerve (8 mm [7-9]). No CSF was observed outside the spinal canal at sacral level. No significant difference between both observers was measured.Conclusion: This study generates evidence for significant CSF extension outside the inner table of the skull. Despite the vicinity of the lens and cochlea, we therefore recommend the inclusion of both optic nerves and internal auditory canals in the clinical target volume for craniospinal irradiation when using highly conformal delivery techniques.

Endocrinologic Consequences of Pediatric Posterior Fossa Tumours

Intracranial tumors are the second most frequent malignancies in children and posterior fossa is a common location for these neoplasias during childhood. Recent advances in surgical techniques, radiotherapy and chemotherapy resulted in dramatic increase in the survival rates of these children, however they are still source of a significant morbidity and mortality. Endocrinological complications and late sequelae of childhood posterior fossa tumours are common among the survivors of these tumours and include growth retardation, hypothyroidism, pubertal disorders, gonadal dysfunction and osteopenia. These complications have significant impact on the quality of life of the survivors of childhood posterior fossa tumours. In this paper, the frequency, etiology, and management of these complications will be reviewed.

Preserving Fertility in Adolescent Girls and Young Women Requiring Craniospinal Irradiation: A Case Report and Discussion of Options to Be Considered Prior to Treatment

Craniospinal irradiation (CSI) is associated with infertility risk for adolescent/young adult women. We explore two methods of reducing ovarian exposure: oophoropexy (surgical removal of the ovaries from the path of the X-ray beam) and proton therapy (to allow the beam to stop without exposing the ovaries/uterus). In the case discussed, oophoropexy followed by X-ray CSI reduced ovarian dose to that at which 50% of oocytes are expected to survive, and the patient appears to have viable oocytes; this technique did not reduce uterine dose. Proton therapy would have eliminated the ovarian and uterine dose and the need for oophoropexy.

Pediatric medulloblastoma: toxicity of current treatment and potential role of protontherapy

Post-operative craniospinal irradiation and systemic chemotherapy are both necessary in the treatment of pediatric medulloblastoma. Late toxicity is a major problem in long term survivors and significantly affects their quality of life. We have systematically reviewed the literature to examine data on late toxicity, specifically focusing on: endocrine function, growth and bone development, neurocognitive development, second cancers, ototoxicity, gynecological toxicity and health of the offspring, cardiac toxicity and pulmonary toxicity. In this paper, we describe qualitatively the kind of detected side effects and, whenever possible, try to assess their incidence and the relative role of craniospinal irradiation (as opposed to other treatments and to the disease itself) in producing them. Subsequently we examine the possible approach to reduce unwanted effects from craniospinal irradiation to target and non-target tissues and we consider briefly the role of hyperfractionation, tomotherapy and IMRT. We describe the characteristics of protontherapy and its potential for non-target tissues toxicity reduction reviewing the existing physical and dosimetric studies and the (still very limited) clinical experiences. Finally we propose intensity modulated spot scanning protontherapy with multiportal simultaneous optimization (IMPT) as a possible tool for dose distribution optimization within different areas of CNS and potential reduction of target tissues toxicity.

Effects of cancer treatment on ovarian function

Causes of primary ovarian failure are reviewed, focusing specifically on cancer treatment-related modalities. Strategies and future directions for protection of the ovaries during cancer therapy, including ovarian transposition, and conformal radiation techniques are presented.

Patterns of failure in children with medulloblastoma treated with 3D conformal radiotherapy

BACKGROUND AND PURPOSE

Craniospinal irradiation for medulloblastoma is one of the most complex techniques employed in radiotherapy. Many reports stress the impact of irradiation quality on survival in these patients. Our report presents the outcome and patterns of failure for 95 patients treated with 3D conformal radiotherapy (3D-CRT).

MATERIALS AND METHODS

From 1998 to 2003, 95 children with medulloblastoma received 3D conformal radiotherapy. All of them were previously treated with surgery and chemotherapy. The brain and upper spinal cord were treated with two lateral 6MV photon fields. In four patients, the cribriform plate was irradiated by the additional field. For primary tumour bed we applied two or three photon beams. Spinal cord was irradiated either with 18-20MeV electron fields or with a mixed beam.

RESULTS

With a median follow-up of 48 months, 32/95 patients suffered a multifocal (21) or isolated (11) recurrence. We evaluated every primary site of failure. In all patients, the recurrence appeared within the isodose level of 95-100%.

CONCLUSIONS

Patterns of failure in medulloblastoma patients treated with 3D conformal radiotherapy indicated that the relapse was mainly associated with poor response to pre-irradiation chemotherapy. We believe that 3D conformal radiotherapy allows avoiding failures, related to radiotherapy uncertainties.