Orbital Radiation Therapy for Thyroid Eye Disease

Disease Modulation Versus Modification: A Call for Revised Outcome Metrics in the Treatment of Thyroid Eye Disease

PURPOSE

This perspective introduces the concepts of disease-modulating and -modifying therapy for thyroid eye disease and offers novel metrics for therapeutic outcomes.

METHODS

A focused literature review was performed.

RESULTS

Modulators are treatments that suppress disease symptoms whereas modifiers alter the natural history of a disease. Though many drugs are capable of exhibiting both effects, consideration of a drug's primary effect is useful when considering therapeutic options. For thyroid eye disease, corticosteroids and teprotumumab are effective at modulating many signs and symptoms of the disease, particularly those related to soft tissue inflammation. Orbital radiotherapy and rituximab have demonstrated effectiveness at durably modifying the natural history of thyroid eye disease.

CONCLUSIONS

Outcome metrics should reflect the unique therapeutic objectives associated with disease modulation and modification. This conceptual framework should guide treatment of thyroid eye disease.

Update on thyroid eye disease: Regional variations in prevalence, diagnosis, and management

Thyroid eye disease (TED) is a rare disease that can lead to decreased quality of life, permanent disfigurement, and vision loss. Clinically, TED presents with exophthalmos, periorbital edema, extraocular muscle dysfunction, and eyelid retraction, and can lead to vision-threatening complications such as exposure to keratopathy and dysthyroid optic neuropathy (DON). Over the last several years, significant advancements have been made in the understanding of its pathophysiology as well as optimal management. Ethnic variations in the prevalence, clinical presentation, and risk of vision-threatening complications of TED are summarized, and risk factors associated with TED are discussed. Additionally, significant advances have been made in the management of TED. The management of TED traditionally included anti-inflammatory medications, orbital radiation therapy, orbital surgical decompression, and biologic therapies. Most recently, targeted therapies such as teprotumumab, an insulin-like growth factor-1 receptor antagonist, have been studied in the context of TED, with promising initial data. In this review, updates in the understanding and management of TED are presented with a focus on the international variations in presentation and management.

Advances in the Treatment of Thyroid Eye Disease Associated Extraocular Muscle Myopathy and Optic Neuropathy

PURPOSE OF REVIEW

To review emerging treatments for thyroid eye disease (TED) associated extraocular muscle myopathy and dysthyroid optic neuropathy (DON).

RECENT FINDINGS

Emerging targeted biologic therapies may alter the disease course in TED. Teprotumumab, a type I insulin-like growth factor receptor inhibitor, is the most recent addition to the treatments available for TED-associated extraocular muscle myopathy causing diplopia. Small studies also suggest a potential therapeutic benefit for DON. Various recent studies have also expanded our knowledge on conventional TED therapies. The therapeutic landscape of TED and its sequelae has evolved in recent years. New targeted therapies have the potential to reduce the extraocular muscle and orbital volume expansion which can lead to diplopia and vision loss from optic nerve compression. Longer term efficacy and durability data is needed to determine the role biologics, such as teprotumumab, should play in the treatment of TED patients compared to the current standard of care.

Advances in steroid sparing medical management of active thyroid eye disease

Thyroid eye disease (TED) is an autoimmune inflammatory disease of the orbit and the most common extrathyroidal manifestation of Graves disease. The release of pro-inflammatory cytokines is associated with inflammation of the ocular surface and lacrimal gland along with periorbital skin erythema and edema. Resultant tissue remodeling, fibrosis, and fat deposition can impart permanent physical changes to the ocular adnexa with effects on function and cosmesis. These changes occur in the active phase of disease, and it is during this time that steroids are often relied on to help alleviate symptoms. Due to the common and predictable side effects of long-term and high-dose steroid use, there has been a continuous effort to find alternative steroid-sparing medical management options for TED. This review highlights the various research studies that support the use of these medications.

Quantitative analysis of extraocular muscle volume and exophthalmos reduction after radiation therapy to treat Graves' ophthalmopathy: A pilot study

PURPOSE

The aim of this study was to provide radiological information on the inherent response of Graves' ophthalmopathy after radiation therapy.

METHODS

Quantitative analysis of extraocular muscle volume was performed on 96 involved extraocular muscles in a total of 16 patients. A total of 48 computed tomography images were analyzed. Exophthalmos was also measured. The percentage reductions in extraocular muscle volume and exophthalmos length were determined and compared to the pre-radiation therapy values at 6-, 12-, and 24-month follow-up.

RESULTS

The median follow-up time was 21.5 months (range: 7.2-29.4 months). The mean reduction in relative tumor volume compared to the pre-radiation therapy extraocular muscle volume was 46.1% (range: 33.3%-58.8%). The mean relative extraocular muscle volumes were 71.5% at 6 months, 59.2% at 12 months, and 54.3% at 24 months after radiation therapy. The volume of the involved extraocular muscles decreased rapidly within the first 12 months of follow-up. The mean pre-radiation therapy length of exophthalmos was 21.7 mm (range: 17.6-26.1 mm). The mean percentages of exophthalmos length by comparison with the pre-radiation therapy length were 96.7% at 6 months, 92.3% at 12 months, and 88.5% at 24 months after radiation therapy. Exophthalmos decreased slowly and steadily during the follow-up period.

CONCLUSION

Quantitative volumetric analysis of the pattern of extraocular muscle volume reduction and exophthalmos length reduction in response to radiation therapy will allow clinicians to better understand the effect of radiotherapy on Graves' ophthalmopathy.

The Effect of Systemic Steroids and Orbital Radiation for Active Graves Orbitopathy on Postdecompression Extraocular Muscle Volume

PURPOSE

To evaluate the effect of orbital radiation prior to surgery on the clinical course and extraocular muscle (EOM) radiologic volume changes after decompression in Graves orbitopathy (GO).

DESIGN

Retrospective, interventional case series.

METHODS

The medical records of patients treated with orbital decompression for GO and who underwent postoperative orbital computed tomography were reviewed. Only patients who underwent rehabilitative decompression in the inactive phase and who received systemic corticosteroids alone (ST group) or combined orbital radiation and systemic corticosteroids (SRT group) in the active inflammatory phase of the disease were selected. The main outcome measure was the comparison of preoperative and postoperative EOM volumes. Secondary outcome measures were changes in proptosis and diplopia after decompression.

RESULTS

Thirty-seven of 114 patients were selected for this study. There were no differences between the ST group (n = 22, 42 eyes) and SRT group (n = 15, 30 eyes) in terms of demographics or predecompression characteristics. After decompression surgery, the total EOM volume significantly increased by 15% in the ST group, but radiated EOMs in the SRT group did not expand, resulting in decreased induction of postoperative diplopia. The percentages of patients showing increased diplopia after decompression differed significantly between the groups (ST group, 40.9% vs SRT group, 13.3%, P = .04). However, there was no difference in exophthalmos reduction after decompression between the 2 groups.

CONCLUSIONS

Orbital radiation prior to orbital decompression can reduce both the postoperative increase in EOM volume and deterioration in diplopia.

Orbital Radiation Therapy in Thyroid Eye Disease

PURPOSE

To review the current literature summarizing the state of knowledge on the use of orbital radiation therapy (ORT) in thyroid eye disease.

METHODS

A systematic review and analysis of the literature were performed. MEDLINE/PubMed, Cochrane Library databases, SCOPUS, and recent relevant journal articles were searched.

RESULTS

Thyroid eye disease is an autoimmune disorder that has the propensity to affect multiple orbital tissues and can cause permanent vision loss. In moderate to severe disease, treatment may be warranted and can include multiple therapeutic modalities. Orbital radiation therapy is frequently used in this setting and may act to break the inflammatory cycle of glycosaminoglycan production and deposition. There has been a wealth of data regarding the effectiveness of ORT in thyroid eye disease resulting in the publication of treatment algorithms and management guidelines; however, there continues to be a lack of conformity among experts on the exact role of ORT in thyroid eye disease.

CONCLUSION

The multiple different thyroid eye disease classification schemes and the concurrent use of other therapeutic modalities challenge the interpretation of studies evaluating the effectiveness of thyroid eye disease. Despite these limitations, the current literature indicates that ORT is generally safe and well tolerated. Orbital radiation therapy may have a modest effect on motility and proptosis early in the disease process. It is unclear whether ORT leads to improved quality of life. There are some data to support the use of ORT to prevent compressive optic neuropathy.

Efficacy of combined orbital radiation and systemic steroids in the management of Graves' orbitopathy

PURPOSE

To compare the efficacy and safety of combination therapy with orbital irradiation and systemic steroids versus steroid monotherapy in the management of active Graves' orbitopathy (GO).

METHODS

The clinical charts of 127 patients with active inflammation due to GO who received intravenous steroid pulse therapy as a first-line treatment with or without orbital radiotherapy between 2010 and 2014 were reviewed. Patients were divided into two treatment groups: 1) combined orbital radiotherapy and steroid pulse therapy (SRT group) and 2) steroid pulse therapy only (ST group). Primary outcome measures included clinical activity score (CAS); NOSPECS classification; ocular motility impairment; and exophthalmos at 1, 3, 6, and 12 months after treatment. The secondary outcome measure was the change in orbital, extraocular muscle (EOM), and fat volume after treatment measured by orbit computed tomography.

RESULTS

Sixty-eight patients were included in the SRT group, and 59 patients were in the ST group. In both treatments, CAS and NOSPECS were significantly reduced. In the comparison of the degree of change from baseline between the groups, the SRT group demonstrated more improvement in NOSPECS and scores of ocular motility. Orbital, EOM, and fat volume significantly decreased in the SRT group; however, only fat volume was reduced in the ST group. Compressive optic neuropathy after treatment developed in 0 % of the SRT group and 3.4 % (2/59) of the ST group. Reactivation of inflammation occurred in 11.8 % (8/68) of the SRT group and 28.8 % (17/59) of the ST group.

CONCLUSIONS

Orbital radiotherapy in combination with steroid treatment significantly improved ocular motility by reducing EOM volume in patients with active GO.

Acute dysthyroid optic neuropathy exacerbated by orbital radiotherapy

A 76-year-old lady presenting with acute dysthyroid optic neuropathy (DON) was stabilised with systemic intravenous methylprednisolone (IVMP). Two separate attempts at a treatment course of orbital radiotherapy (OR) were commenced and subsequently abandoned as there was an acute worsening of her DON during OR, despite cover with oral glucocorticoids and subsequently IVMP. The patient underwent urgent orbital decompression which normalised her vision and optic neuropathy. Our case likely represents worsening of DON due to soft tissue swelling secondary to OR despite cover with IVMP in a patient previously responsive to IVMP alone. Some authors advocate the use of OR in active DON as either a surgery delaying or surgery sparing alternative. This case report illustrates the rare risk of transiently worsening DON with OR. We highlight the need for close monitoring of optic nerve function if OR is utilised in this patient group.

Reduced risk of compressive optic neuropathy using orbital radiotherapy in patients with active thyroid eye disease

PURPOSE

To compare the risk of developing compressive optic neuropathy in patients with active thyroid eye disease (TED) treated with corticosteroids with or without orbital radiotherapy.

DESIGN

Retrospective single-center case-control study.

METHODS

The clinical charts of 351 patients with active TED who received corticosteroids with or without orbital radiotherapy between 1999 and 2010 were reviewed. Patients with compressive optic neuropathy at the time of presentation were excluded. Group 1 received corticosteroids only and Group 2 received corticosteroids as well as orbital radiotherapy. The primary outcome measure was the development of compressive optic neuropathy. Secondary outcome measures were changes in other parameters indicating the activity of TED, including soft tissue inflammation, diplopia, ocular motility restriction, and appearance.

RESULTS

There were 144 cases in Group 1 and 105 in Group 2. Both groups were matched for age, sex, and stability of thyroid function. The 2 groups differed only in the modality of treatment for active TED. The main indication for treatment in both groups was soft tissue inflammation. Corticosteroids were initiated an average of 2.6 months following symptom onset in Group 1 and 2.5 months in Group 2. Group 2 received orbital radiotherapy on average 4.2 months following the initiation of corticosteroid therapy and 8% (9/105) were intolerant to corticosteroids. At an average of 3.2 years follow-up, compressive optic neuropathy had developed in 17% (25/144) of Group 1 and 0% of Group 2 (P < .0001), on average 5.5 months following the initiation of corticosteroid therapy. Although both groups experienced a significant reduction in periocular inflammation, the radiotherapy-treated group demonstrated a significantly greater improvement in ocular motility.

CONCLUSION

The rate of compressive optic neuropathy was significantly lower and improvement in ocular motility greater in patients receiving orbital radiotherapy in addition to corticosteroids. Patients with active TED appear to have an effective and sustained response to orbital radiotherapy combined with corticosteroids that is protective against disease progression and the development of compressive optic neuropathy.