A 53-year-old man with no significant past medical history presented with a 6-month history of pain when swallowing and regurgitation. Esophagogastroduodenoscopy revealed a large, circumferential, distal esophageal mass, with biopsy revealing adenocarcinoma. Staging PET/CT did not reveal any regional lymphadenopathy or distant spread of disease. The patient underwent an en bloc esophagectomy, with pathology demonstrating T3N2 (stage IIIB) disease, and he was subsequently treated with adjuvant chemotherapy. He was well, with no clinical or radiographic evidence of disease recurrence for 4 months, until he began experiencing pain and vision loss in his left eye.
Ophthalmic exam showed a visual acuity of 20/20 in the right eye and 20/100 in the left. Intraocular pressure in both eyes and an examination of the right eye was normal. In the left eye, the pupil was irregular and poorly reactive, but there was no afferent pupillary defect. There was a cystic thickening of the iris stroma with eversion of the temporal pupillary margin (fig. ). Dilated fundus exam of the left eye showed cystoid macular edema, but no choroidal metastasis. Ultrasound biomicroscopy and anterior segment OCT suggested that the lesion was only in the iris and did not involve the ciliary body, although it may have extended to the iris root. Contrast-enhanced CT of the head and MRI of the brain and orbit did not reveal any abnormal mass or suspicious enhancing lesions. In addition, a restaging PET/CT scan did not reveal disease recurrence elsewhere in the body.
The patient was diagnosed clinically with isolated metastasis to the iris. Intraocular biopsy was not performed to avoid the risk of tumor seeding at distant sites via the iris vascularization. He began treatment with intravitreal bevacizumab 1.25 mg for cystoid macular edema and was referred for radiation therapy. The patient was simulated in the supine position and a frameless technique was utilized, which included a custom aquaplast mask with U-frame for immobilization. The previously acquired contrast-enhanced CT and MRI were fused to the planning CT simulation, and all previous clinical evaluations were carefully analyzed to help delineate the target volume and normal surrounding critical structures. The gross tumor volume was defined, and then the clinical target volume was determined. Due to concerns about eye motion, the clinical target volume was contoured to include as much of the anterior half of the orbit as possible. A planning target volume margin of 2 mm was added.
The Novalis ExacTrac patient positioning platform (Brainlab AG, Heimstetten, Germany) was used for immobilization. Treatment planning was performed using the BrainScan system (Brainlab AG). Highly conformal radiation therapy, consisting of 8 fixed beams, was used to deliver 35 Gy in fourteen 2.5-Gy daily fractions using 6 MV photons with a 0.5-cm bolus (fig. ). For quality assurance, CT fusions were done after the dry run and fifth fraction.
The patient received a total of 2 bevacizumab injections separated by 1 month. The second occurred 3 days before his first radiation treatment. When the patient returned 3 weeks later, he had acute anterior uveitis with 3+ anterior chamber cell and flare. His vision had decreased to 20/400, and cystoid macular edema worsened. Rather than bevacizumab, 4 mg of intravitreal Triesence was administered. One month later, which was 2 weeks after completion of SBRT, the patient reported subjective visual improvement. Anterior uveitis and cystoid macular edema were improving. Treatment continued with prednisolone acetate 1% four times daily in the left eye. One month later, the iris metastasis had totally regressed and his vision improved to 20/150. At follow-up 6 months after the last radiation treatment, there was no recurrence of the iris metastasis (fig. ), his macular edema had totally resolved, and Snellen visual acuity had returned to 20/30.
