Radiation optic neuropathy after external beam radiation therapy for acromegaly

Radiation-Induced Retinopathy and Optic Neuropathy after Radiation Therapy for Brain, Head, and Neck Tumors: A Systematic Review

Background: Patients with brain, head, and neck tumors experience a decline in their quality of life due to radiation retinopathy and optic neuropathy. Little is known about the dose–response relationship and patient characteristics. We aimed to systematically review the prevalence of radiation retinopathy and optic neuropathy. Method: The primary outcome was the pooled prevalence of radiation retinopathy and optic neuropathy. The secondary outcome included the effect of the total radiation dose prescribed for the tumor according to the patient’s characteristics. Furthermore, we aimed to evaluate the radiation dose parameters for organs at risk of radiation retinopathy and optic neuropathy. Results: The pooled prevalence was 3.8%. No retinopathy was reported for the tumor’s prescribed dose of <50 Gy. Optic neuropathy was more prevalent for a prescribed dose of >50 Gy than <50 Gy. We observed a higher prevalence rate for retinopathy (6.0%) than optic neuropathy (2.0%). Insufficient data on the dose for organs at risk were reported. Conclusion: The prevalence of radiation retinopathy was higher compared to optic neuropathy. This review emphasizes the need for future studies considering retinopathy and optic neuropathy as primary objective parameters.

Radiotherapy for the treatment of pituitary adenomas: A dosimetric comparison of three planning techniques

AIM

Our goal was to compare conformal 3D (C3D) radiotherapy (RT), modulated intensity RT (IMRT), and volumetric modulated arc therapy (VMAT) planning techniques in treating pituitary adenomas.

BACKGROUND

RT is important for managing pituitary adenomas. Treatment planning advances allow for higher radiation dosing with less risk of affecting organs at risk (OAR).

MATERIALS AND METHODS

We conducted a 5-year retrospective review of patients with pituitary adenoma treated with external beam radiation therapy (C3D with flattening filter, flattening filter-free [FFF], IMRT, and VMAT). We compared dose-volume histogram data. For OARs, we recorded D2%, maximum, and mean doses. For planning target volume (PTV), we registered V95%, V107%, D95%, D98%, D50%, D2%, minimum dose, conformity index (CI), and homogeneity index (HI).

RESULTS

Fifty-eight patients with pituitary adenoma were included. Target-volume coverage was acceptable for all techniques. The HI values were 0.06, IMRT; 0.07, VMAT; 0.08, C3D; and 0.09, C3D FFF (p < 0.0001). VMAT and IMRT provided the best target volume conformity (CI, 0.64 and 0.74, respectively; p < 0.0001). VMAT yielded the lowest doses to the optic pathway, lens, and cochlea. The position of the neck in extreme flexion showed that it helps in planning mainly with VMAT by allowing only one arc to be used and achieving the desired conformity, decreasing the treatment time, while allowing greater protection to the organs of risk using C3D, C3DFFF.

CONCLUSIONS

Our results confirmed that EBRT in pituitary adenomas using IMRT, VMAT, C3D, C3FFF provide adequate coverage to the target. VMAT with a single arc or incomplete arc had a better compliance with desired dosimetric goals, such as target coverage and normal structures dose constraints, as well as shorter treatment time. Neck extreme flexion may have benefits in treatment planning for better preservation of organs at risk. C3D with extreme neck flexion is an appropriate treatment option when other treatment techniques are not available.

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.

Factors Associated with Occurrence of Radiation-induced Optic Neuropathy at "Safe" Radiation Dosage

BACKGROUND

Radiation-induced optic neuropathy (RION) is a rare, and often visually devastating, complication of radiation therapy (RT) near the anterior visual pathways.

METHODS

A retrospective case series of patients who developed RION at a tertiary medical center, followed by a case-control study comparing RION cases with matched controls who received RT.

RESULTS

Thirteen patients (18 eyes) with RION were identified. Radiation modalities included external beam photon radiation, whole brain radiation, stereotactic radiosurgery, proton beam, and unknown. Most patients received doses below published "safe" thresholds (<55 Gy; <8-10 Gy for stereotactic radiosurgery). There was no statistically significant difference in prevalence of vasculopathic factors between cases and controls; on subgroup analysis in three patients who received surprisingly low radiation doses, smoking (p=0.05) and hypertension (p=0.02) appeared more prevalent.

CONCLUSION

RION can occur at doses below published "safe" thresholds and with different RT modalities. Smoking and hypertension might be risk factors for RION.

Radiation therapy in the management of pituitary adenomas

Radiation therapy in the form of fractionated treatment or radiosurgery has an important role in the management of pituitary adenomas. Radiation is a reliable way of gaining local control for radiographically progressing pituitary adenomas. For functioning adenomas that are biochemically recurrent or persistent, radiation therapy is less consistent in offering biochemical normalization and often requires a latency period of years or decades. The decision of when to use radiation therapy is a delicate balance between its benefits and late sequelae, especially in the context of benign disease. Recent technological advances in radiation oncology hold the potential to minimize dose to uninvolved normal tissue and therefore reduce the risk of toxicity.

Fractionated stereotactic radiosurgery using the Novalis system for the management of pituitary adenomas close to the optic apparatus

Radiosurgery has been proven to be an effective treatment for residual or recurrent pituitary adenomas after surgery. However, it causes severe complications when the optic apparatus is irradiated over the tolerance dose. In this study, we analyzed the feasibility of fractionated stereotactic radiosurgery to treat pituitary tumors close to the optic apparatus. Thirty-four patients from June 2006 to June 2011 with recurrent or residual pituitary adenomas close to (<3 mm) the optic apparatus were treated with fractionated stereotactic radiosurgery. Three fractions with a total dose of 2100 cGy were applied to the tumors. Imaging, examination of vision, and estimation of hormone level were regularly performed before and after radiosurgery. The mean tumor volume before fractioned stereotactic radiosurgery was 5.06±3.08 cm3 (range: 0.82-12.69 cm3). After a mean follow up of 36.8±15.7 months (range: 16-72 months), tumor size was reduced in seven (20.6%) patients and remained the same in the other 27 (79.4%) patients. Vision was improved in one patient and remained stable in the rest. Only one patient developed transient post-treatment diplopia. This study suggests that fractionated stereotactic radiosurgery is safe for treating pituitary adenomas close to the optic apparatus. Studies with more patients and longer follow-up are required to draw definite conclusions.

Optic neuropathy following radiotherapy for Cushing's disease: case report and literature review

Radiation-induced optic neuropathy is a rare adverse effect of radiotherapy applied for the treatment of pituitary adenomas. We report a patient with a recurrent adrenocorticotrophin secreting pituitary adenoma who received external beam irradiation after failing surgical and medical therapy. Sixteen months after radiotherapy, the patient was presented with declining visual acuity, and radiation-induced optic neuropathy was diagnosed. Despite treatment with glucocorticoids and hyperbaric oxygen, her vision did not improve. The pathophysiology, prevention and treatment of radiation-induced optic neuropathy, including the efficacy of hyperbaric oxygen therapy are reviewed.

Radiation dose-volume effects of optic nerves and chiasm

Publications relating radiation toxicity of the optic nerves and chiasm to quantitative dose and dose-volume measures were reviewed. Few studies have adequate data for dose-volume outcome modeling. The risk of toxicity increased markedly at doses >60 Gy at approximately 1.8 Gy/fraction and at >12 Gy for single-fraction radiosurgery. The evidence is strong that radiation tolerance is increased with a reduction in the dose per fraction. Models of threshold tolerance were examined.

Multisession CyberKnife radiosurgery for optic nerve sheath meningiomas

Optic nerve sheath meningiomas (ONSMs) are benign lesions originating from the dural sheath of the optic nerve. Progressive growth can lead to gradual loss of vision and exophthalmos. Loss of vision following microsurgical resection is not uncommon, and although stereotactic fractionated radiotherapy can be a safe alternative to control tumor growth and preserve vision, it may also lead to complications. Frame-based stereotactic radiosurgery has only been rarely used because single-fraction high-dose treatments of intrinsic optic nerve lesions may induce unacceptably high toxicity. New frameless radiosurgery devices such as the robotic CyberKnife, an image-guided radiosurgery system, can provide the extremely tight conformality and submillimetric accuracy of frame-based systems combined with the possibility of delivering radiation in several sessions. In the present report the authors review the clinical presentation and management of ONSMs and describe their preliminary experience using multisession radiosurgery to treat these lesions.

Ophthalmic and adnexal complications of radiotherapy

The role of radiotherapy in ophthalmic practice continues to grow. This growth has seen an expansion of indications for radiotherapy, a refinement of the modalities that can be used and a reduction in the ocular and adnexal complications that result from this form of therapy. The compendium of indications for radiotherapy in ophthalmology continues to grow and now includes many conditions such as the treatment of lid and adnexal disease, ocular surface disorders and both benign and malignant disease of the posterior segment and optic pathways. The radiotherapeutic modalities employed to manage these conditions are numerous and include both radioactive plaques (brachytherapy) and external beam radiation techniques. New techniques such as stereotactic radiosurgery are delivering benefits in the management of conditions such as optic nerve sheath meningioma, where the treatment of this blinding and occasionally life-threatening intracranial neoplasm now results in fewer adverse affects. The purpose of this review is to give a brief overview of the indications and treatment modalities, and a more in-depth discussion of the potential side-effects when radiotherapy is used for ocular and periorbital disease.

Experience of external beam radiotherapy given adjuvantly or at relapse following surgery for craniopharyngioma

BACKGROUND AND PURPOSE

Evaluation of effect of timing of external beam radiation therapy (EBRT) following surgery for craniopharyngioma.

MATERIALS AND METHODS

Between 1976 and 2002, 87 patients (28 children) received EBRT in a regional referral centre. Forty-four patients received EBRT adjuvantly and 43 on relapse. The median total dose was 42.5Gy (range 34.7-52.5Gy) in 2.25-2.83Gy fractions over a median of 20 days (range 17-32). Effect of EBRT timing, type of original surgery, age on survival, progression-free survival (PFS) and quality of life (QOL) was studied.

RESULTS

Survival from diagnosis was 86 and 76% and PFS was 78 and 66% at 10 and 20 years, respectively, with no significant difference seen between those treated adjuvantly or at relapse or according to age. QOL deteriorated significantly from diagnosis to last follow-up. Excluding patients who relapsed following EBRT, QOL did not deteriorate significantly overall (P=0.35). Children had worse QOL and greater morbidity at all timepoints compared to adults.

CONCLUSIONS

EBRT is effective both adjuvantly and at relapse. QOL deteriorates over time-relapse following EBRT was the only significant factor. Children have greater morbidity compared to adults, but no evidence for greater EBRT-induced toxicity was seen.

The long-term efficacy of conventional radiotherapy in patients with GH-secreting pituitary adenomas

OBJECTIVE

To assess the long-term efficacy and safety of conventional radiotherapy (RT) in the control of acromegaly according to recent stringent criteria of cure.

DESIGN

A retrospective longitudinal study.

PATIENTS AND METHODS

Forty-seven patients with active acromegaly were treated with conventional RT between 1982 and 1994. All patients were first operated on and successively irradiated at a dose of 45-50 Gy in 25-28 fractions for persistent (n = 40) or recurrent (n = 7) disease.

MEASUREMENTS

Long-term GH/IGF-I secretion and local tumour control were evaluated regularly, and possible side-effects were searched for systematically, especially in terms of secondary endocrine dysfunction. Biochemical cure of acromegaly was defined by glucose-suppressed plasma GH levels below 1 microg/l during an oral glucose tolerance test (OGTT) and normal age-corrected IGF-I values.

RESULTS

The 5-, 10- and 15-year overall survival rates were 98%, 95% and 93%, respectively. Suppression of GH during OGTT was seen in 9% of patients at 2 years, 29% at 5 years, 52% at 10 years, and 77% at 15 years. Age-corrected IGF-I levels were normal in 8% of patients 2 years after RT, and this proportion increased to 23%, 42% and 61% after 5, 10 and 15 years, respectively. Normalization of GH/IGF-I mainly depended on pre-RT levels. Local tumour control was 95% at 5, 10 and 15 years after treatment. Late toxicity was mainly represented by progressive hypopituitarism, which was present in 33% of patients at baseline and increased to 57%, 78% and in 85% of patients at 5 10 and 15 years after RT, respectively.

CONCLUSION

Conventional RT is effective in the long-term control of GH-secreting pituitary adenomas, although with a high prevalence of progressive hypopituitarism. At present, it remains a suitable option in acromegalic patients uncontrolled by surgery or medical therapy.

Lack of Radiation Optic Neuropathy in 72 Patients Treated for Pituitary Adenoma

The incidence of radiation optic neuropathy (RON) after external photon beam radiation therapy for nonfunctioning pituitary adenoma (NFA) is not well-studied. Retrospective review of ophthalmological and imaging data in 72 patients with NFA treated between 1985 and 1998 with external beam radiation therapy after surgery Clinical follow-up after radiation therapy had to be at least 18 months. RON was defined as a sudden and profound irreversible visual loss affecting the optic nerve or chiasm A review of previously published cases of RON was then performed. In our cohort, no patient had RON. A total of 11 adequately documented series reports of RON were found in the medical literature on radiation-treated NFAs. The incidence of RON in NFA from these series is 0.53% (95% CI, 0.26%-0.96%). An additional 14 single RON cases have been reported, bringing the total of adequately documented RON cases to 25. RON is a rare complication after external beam radiation therapy for NFA.