Assessment of Radiation-Induced Optic Neuropathy in a Multi-Institutional Cohort of Chordoma and Chondrosarcoma Patients Treated with Proton Therapy

Simple Summary

Proton therapy is an effective therapeutic option for the treatment of skull-base tumors that require high radiation doses to be controlled. On rare occasions, patients suffer from radiation-induced optic neuropathy (RION) to the detriment of their post-treatment quality-of-life. We have collected multi-institutional data of 289 skull-base patients having received high doses to the optic apparatus from proton therapy or proton–photon mixed treatments and have observed a RION incidence rate (all grades) of 4.2% (12). We have furthermore confirmed older age and hypertension as risk factors for the onset of this side effect, with tumor involvement or its proximity to the optic apparatus and repeated surgical procedures showing moderate association. Our findings were consolidated into a NTCP model that can support pre-treatment patient segmentation into risk groups and the planning of necessary treatment countermeasures. However, further data and validation are necessary to confirm validity of the model.

Abstract

Radiation-induced optic neuropathy (RION) is a rare side effect following radiation therapy involving the optic structures whose onset is, due to the low amount of available data, challenging to predict. We have analyzed a multi-institutional cohort including 289 skull-base cancer patients treated with proton therapy who all received >45 Gy_RBE to the optic apparatus. An overall incidence rate of 4.2% (12) was observed, with chordoma patients being at higher risk (5.8%) than chondrosarcoma patients (3.2%). Older age and arterial hypertension, tumor involvement, and repeated surgeries (>3) were found to be associated with RION. Based on bootstrapping and cross-validation, a NTCP model based on age and hypertension was determined to be the most robust, showing good classification ability (AUC-ROC 0.77) and calibration on our dataset. We suggest the application of this model with a threshold of 6% to segment patients into low and high-risk groups before treatment planning. However, further data and external validation are warranted before clinical application.

Radiation induced optic neuropathy: Does treatment modality influence the risk?

Radiation induced optic neuropathy (RION) is a rare but disastrous complication of radiation therapy in treatment of periorbital tumors. The objective of this study is to investigate the incidence of RION in series of patients treated from peri orbital tumors by recent photon and proton irradiation modalities. We searched the Pub Med database for studies in periorbital tumors including base of skull, sinonasal, pituitary, nasopharyngeal tumors and craniopharyngioma treated with Intensity modulated radiotherapy (IMRT) and with proton beam therapy (PBT) between 1992 and 2017 excluding metastatic tumors, lymphomas, pediatric series, those treated mainly with chemotherapy, target therapy and those written in languages other than English and French. The result retrieved 421 articles that were revised by the panel. Fourteen articles with IMRT and 27 with PBT reported usable data for the review from which 31studies that had pointed to the doses to the optic nerve (ON) and/or optic chiasm (OC) and incidence of RION have been analyzed. We have found that the incidence of RION had been reported fairly in both modalities and many other factors related to the patient, tumor, and irradiation process interplay in its development. We have concluded that proper treatment planning, good selection of treatment modality, adherence to dose constraints applied to critical structures all along with regular oncological and ophthalmological follow up, control of co-morbidities and early intervention, could help reducing its magnitude.

Clinical Features of the Patients with Neuromyelitis Optica Spectrum Disorder

Introduction

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory, demyelinating syndrome of the central nervous system (CNS) that predominantly affects the spinal cord and optic nerves. Since it was first described, new information about the pathophysiology gained momentum with the discovery of an antibody against Aquaporin-4, a water channel protein that is predominantly found in the astrocytes. In our study, we evaluated the clinical features of NMOSD and clinically related CNS disorders.

Method

In our study, we recruited patients that were followed by Clinic for Multiple Sclerosis and Myelin Disorders at Istanbul University between 1979 and 2016.

Results

Thirty-five NMOSD, fifteen relapsing inflammatory optic neuropathy (RION) and ten opticospinal multiple sclerosis (OSMS) patients were recruited in our study. Forty-eight patients (%80) were female and twelve (%20) were male. Age, sex, follow-up period, annualized relapse rate, relapses in the first two years and progression index were similar between the groups. Cerebrospinal fluid (CSF) protein levels were higher in the NMOSD group. Concomitant autoimmune disorders were observed in six NMOSD patients and two OSMS patients. One patient with RION had nonspecific white matter lesions without gadolinium enhancement in the brain MRI.

Conclusion

Laboratory and imaging findings suggests that NMOSD is a distinct disorder than RION and OSMS. Further studies are needed to say specific comments about the existence of OSMS.

Radiation-induced optic neuropathy after stereotactic and image guided intensity-modulated radiation therapy (IMRT)

BACKGROUND/PURPOSE

To quantify the risk of radiation-induced optic neuropathy (RION) after stereotactic/image-guided positioning and intensity-modulated radiotherapy (IMRT) with ≥50 Gy to the anterior visual pathway (AVP).

METHODS

Patients irradiated with ≥50 Gy to the AVP using stereotactic/image-guided positioning between 2002 and 2011 in Mannheim were identified. Detailed dosimetric data were collected and patients or family members were retrospectively asked to rate visual acuity and visual disorders.

RESULTS

125 patients fulfilled the eligibility criteria. Average maximum equivalent point dose (D_max-EQD-2_[α/β=1.6]) to the AVP was 53.1 ± 3.9 Gy. 99 patients received ≥50 Gy bilaterally (chiasm or both optic nerves), resulting in 224 (99x2 bilateral plus 26 unilateral) visual-fields-at-risk (VFAR) for RION. Eighty-two patients provided pre/post-IMRT visual status information (n = 151 VFARs). Permanent visual deterioration occurred in 18 (22%) patients. In seven, visual deterioration was possibly related to radiotherapy (two-sided deterioration in one patient) for a crude incidence of 8.5% (7/82 patients) and 5.3% (8/151 VFARs). Two cases were caused by chronic keratitis/conjunctivitis; in five patients RION could not be excluded (one two-sided). In one of 13 patients with D_max-EQD-2 > 58 Gy, RION could not be excluded. In all affected patients, visual acuity post-IMRT had decreased only mildly (1-2 points on the 5-point-scale). One patient with relevant baseline visual impairment (3/5) developed unilateral blindness (crude incidence of blindness on patient-/VFAR-level: 1.2% and 0.66%; competing risk-adjusted/actuarial 24-month incidence: patient/VFAR-level: 1.8% and 0.95%).

CONCLUSION

Risk of RION was low in this cohort with accurate positioning and precise dosimetric information. Less conservative tolerance doses may be considered in patients with high risk of recurrence.

Aquaporin-4 antibody negative recurrent isolated optic neuritis: clinical evidence for disease heterogeneity

Recurrent optic neuritis is frequently observed in multiple sclerosis (MS) and is a typical finding in neuromyelitis optica (NMO). Patients that lack further evidence of demyelinating disease are diagnosed with RION (recurrent isolated optic neuritis) or CRION (chronic relapsing inflammatory neuropathy) if they require immunosuppressive therapy to prevent further relapses. The etiology and disease course of this rare condition are not well defined. We studied a series of 10 patients who presented with recurrent episodes of isolated optic neuritis (ON, n=57) and were followed over a median of 3.5 years. Visual acuity was severely reduced at the nadir of the disease (20/200 to 20/800). All patients had MRI non-diagnostic for MS/NMO and were aquaporin-4 antibody negative. Six patients fulfilled the CRION criteria. In two of these a single ON followed by a long disease-free interval preceded development of CRION for years, suggesting the conversion of an initially "benign" isolated ON into the chronic relapsing course. Cerebrospinal fluid (CSF) analysis revealed mild pleocytosis in 5 patients, identical oligoclonal bands in serum and CSF were observed in 2 patients, while the others remained negative. In conclusion, recurrent ON is a disease entity that requires aggressive glucocorticoid and eventually long-term immunosuppressive therapy to prevent substantial visual impairment.