Written by Paul T. Finger, MD
Malignant tumors from other parts of the body can spread in and around the eye. These tumors may never be discovered unless they affect vision, are visible to the patient, or push the eye forward. The most common location for ocular metastasis, in the vascular layer called the choroid (choroidal metastasis) within the eye.
Cancer metastasis that appear in and around the eye are usually from a breast cancer (in women) and lung cancer (in men). Other less common sites of origin include the prostate, the kidney, the thyroid, and gastrointestinal tract. Blood cell cancer (lymphoma and leukemia) can also metastasize to the eye and orbit. Once a patient is diagnosed with choroidal metastasis, we try to find where it came from. In 18% of patients, we do not find the source of choroidal metastasis. In these cases, we may have to biopsy the ocular tumor and look at its cell-type.
Most patients with choroidal metastasis have no symptoms. If the metastasis is on the eye or eyelids, it may be visible. If located behind the eye (in the orbit), the metastasis can push the eyeball out or to the side. If within the eye (the most common), choroidal metastasis patients can see flashing lights, floating spots or distortion of their vision. Patients with a history of cancer are at greatest risk and should have periodic eye examinations.
Most patients with metastasis have either a known primary cancer and/or metastatic tumors in other parts of their body. A careful medical history can uncover the signs or symptoms of these other cancers. If an eye cancer specialist suspects ocular metastasis, both eyes and orbits should be examined because ocular metastases can be both bilateral and/or multifocal.
Choroidal metastasis is usually non-pigmented (except metastatic melanomas), and has typical ultrasound and angiographic patterns. Choroidal metastasis is usually poorly circumscribed and can cause retinal detachments. They may have spicules of pigment on their surface. Unlike primary choroidal melanoma, they can grow quickly (weeks) and may require prompt treatment.
The patient with metastasis to the eye should also be examined by a medical oncologist. A complete metastatic survey should be performed to “stage” the patient (to see if there are other tumors within the body). Specifically, computed radiographic imaging of the brain and lung should be performed due to a high concurrent incidence of intracranial and pulmonary metastases. Your doctor may suggest a total body PET/CT with fusion.
The care of patients with metastasis to the eye typically involves cooperation between the eye cancer specialist, medical oncologist, and radiation therapist. Though chemotherapy can be used in many cases of orbital and choroidal metastasis, radiation therapy is usually a more definitive treatment. If the metastatic tumor has not destroyed the center of the retina, early treatment offers the best hope for preserving vision. Almost all patients with choroidal metastasis can be treated with external beam radiation. That is, surgery is rarely needed as treatment for choroidal metastasis. Orbital and adnexal ocular metastasis are typically biopsied prior to treatment.
After irradiation, a regressed choroidal metastasis displays spicular hypertrophy of the retinal pigment epithelium.
Most patients who develop posterior choroidal metastasis can either be closely monitored for tumor growth, followed for response to chemotherapy, or treated with external beam irradiation. Radioactive plaque radiotherapy is rarely needed. If chemotherapy is not an option, prompt external beam irradiation (typically 30-40 Gy), may offer the best chance for preservation of vision.
In those rare cases where the metastasis spreads to the iris, patients can develop severe glaucoma and may lose their eye. Thankfully, anterior segment (iris) metastases are rare. Since most cancers do not spread to the iris, most patients with intraocular, choroidal and orbital metastasis respond well to treatment and keep their vision.