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Early cancer detection key to saving lives and preserving vision
With no effective treatments for metastatic disease, physicians must try to detect ocular melanomas at an early stage, before they spread.
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Carol L. Shields |
Early melanoma detection is vital for saving eyes and saving lives, according to Carol L. Shields, MD. Dr. Shields said she has made it a career goal to inform ophthalmologists and other physicians of the critical need for early detection of ocular melanoma.
Dr. Shields said she and her colleagues in the oncology service at Wills Eye Hospital emphasize the importance of detecting ocular melanomas at the earliest stage possible, before the tumors have “secretly” metastasized.
“I use the word ‘secretly’ because it is estimated that by the time the ophthalmologist detects a melanoma in the eye, the tumor, on average, had already metastasized 5 years earlier,” Dr. Shields told Ocular Surgery News in a telephone interview. “This tells us that we’re detecting melanoma in the eye way too late.”
Dr. Shields said the priorities for ocular oncologists are different from those of general or comprehensive ophthalmologists.
“Unlike most ophthalmologists, who have vision as their first concern, as ocular oncologists our first concern is the patient’s life, our second concern is to save their eye and our third concern is their vision,” she said.
The average ophthalmologist is likely to see one or two patients in his or her career with melanoma of the eye, Dr. Shields said, “but if the ophthalmologist could detect that melanoma at a very early stage, they could possibly save the life of that patient.”
Primary eye cancer
Melanoma is the most common primary eye cancer: that is, cancer that originates in the eye.
“Everyone has heard of melanoma, because it most often affects the skin rather than the eye,” Dr. Shields said.
Each year in the United States there are 60,000 cases of skin melanoma and 2,000 cases of choroidal melanoma, she said.
“Overall, melanoma of the eye spreads and leads to death in approximately 30% to 50% of patients,” she said. “When it spreads it most often enjoys living in the liver and the lungs. And once it spreads, the life survival is under 1 year. Melanoma is one of the most dangerous eye conditions that any ophthalmologist deals with.”
Early detection
The bad news is that there is no effective treatment for metastatic disease.
“When a patient has metastatic disease, survival is poor,” she said. “There is a lot of research going on in this area, but nothing really seems to help these patients.”
The best way to forestall the death sentence is by early detection of the tumor in the eye, before it has a chance to metastasize, Dr. Shields said.
“My personal goal in my career is to help to teach ophthalmologists and medical doctors in general how to detect an intraocular melanoma at a very early stage,” she said.
About 20 years ago, the average thickness of an ocular melanoma at the time of detection was 5.5 mm, Dr. Shields said. Today, the average ocular melanoma is about 3.5 mm when detected.
“My goal is to get it under 1 mm. You might think that seems far-fetched, but it’s not at all,” Dr. Shields said.
By way of comparison, she noted that in the 1960s skin melanomas were an average thickness of 4 mm when detected; that is more than four times the average size at which they are detected at today.
“The life prognosis with skin melanoma has greatly improved,” she said. “So we have to improve as ophthalmologists.”
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Images: Shields CL |
Detecting melanoma
For 20 years, Dr. Shields and colleagues have been searching for better ways to detect choroidal melanomas.
“We have analyzed thousands of patients retrospectively, looking for risk factors that might help to select out the one melanoma hidden among thousands of nevi that look a lot like a small melanoma. We’re going to see thousands of nevi before we find that one melanoma,” she said.
There are risk factors that help physicians identify melanomas.
“We remember these risk factors by the mnemonic ‘To Find Small Ocular Melanoma,’” Dr. Shields said.
The T stands for thickness over 2 mm, F for subretinal fluid, S for symptoms, O for orange pigment and M for margin within 3 mm of the optic disk, she said.
“If a patient has none of these risk factors, then it is very unlikely that this small tumor is melanoma,” Dr. Shields said. “But if a patient has just one risk factor, there is a 30% chance that tumor will grow to a bigger melanoma within 5 years. If a patient has three or more of these risk factors, then that tumor is highly likely to be a melanoma because it has over 50% chance for growth in 5 years.”
If comprehensive ophthalmologists are not comfortable with making a judgment, they can seek consultation with experts, she said. Today it is easy to e-mail a retinal photograph to tertiary subspecialists such as Dr. Shields and her colleagues, who can give an opinion.
“Each day in our practice we get several e-mail consults with questions like, ‘What is this?’ or ‘What should I do?’ or ‘Do you need to see the patient?’ That is good medicine,” she said. “We don’t make diagnoses by e-mail, but we give help to the ophthalmologist, and we’re always available to help out.”
Systemic metastasis
The most common cancer of the eye is believed to be metastasis: that is, a cancer that originated elsewhere in the body, typically in the breast, lung or colon, and spread to the eye, Dr. Shields said.
“Most of the patients who have metastasis are very ill by the time it is spread to the eye, and they do not see the eye doctor because they have disease elsewhere that is more serious,” she said. “It is estimated that about 2% of people with systemic cancer will show a metastasis in one of their eyes.”
With the high prevalence of breast, lung and prostate cancers, most ophthalmologists are likely to treat a few patients with choroidal metastasis in their career, she said.
Breast cancer is the most common cancer to shed metastases to the eye; about 50% of all choroidal metastases originate from the breast, Dr. Shields said.
“If you see a patient with choroidal metastasis, the life prognosis is poor, with an average survival of about 9 or 10 months,” she said. “Patients with cutaneous melanoma and lung cancer metastatic to the eye tend to have the least survival. Those with breast cancer and carcinoid tumor can have the best survival.”
Lung cancer is the second most common cancer that sheds metastases to the eye, with about 20% of all choroidal metastases originating from the lungs, Dr. Shields said.
“The most important phone call you can make when you see a patient with choroidal metastasis is to their oncologist because it is the oncologist who is going to lay out the plan,” she said.
Recognizing symptoms
With metastatic tumors, patients often have symptoms of blurred vision. Less commonly they complain of pain, which they might describe as a deep ache or even a severe pain that wakes them from sleep.
Upon intraocular examination, the ophthalmologist will see subretinal fluid involving the fovea and a “creamy yellow mass” that is usually about 2 mm to 3 mm in thickness in the macular region, Dr. Shields said.
“Fortunately most metastases to the eye are sensitive to radiotherapy, so we can reassure the patient that they’re not likely to lose their eye, and they possibly may regain their vision following radiation,” she said. “It’s a really scary thing to have systemic cancer and then lose vision with a potential for blindness. To the patient, their vision provides them good quality of life, and if they lose their vision the quality of life worsens.”
Pediatric tumors
Retinoblastoma, a rare cancer of the eye, affects about one in 15,000 children, according to Dr. Shields.
“No one knows the exact cause, and in two-thirds of cases it is unilateral. If untreated, it is fatal,” she said.
The detection of retinoblastoma is late worldwide, but in the United States and some other developed countries detection is early, while the tumor is still in the eye, Dr. Shields said.
“Metastasis occurs from retinoblastoma in less than 3% of cases in the United States, but worldwide 50% of children with retinoblastoma still die from metastatic disease,” she said. “If the tumor is limited to the eye, then we feel comfortable that the child will have a good prognosis. These kids with retinoblastoma should be handled only at centers where there are retinoblastoma experts. When a child is suspected of having retinoblastoma, do not delay.”
Each year about 300 children are diagnosed with retinoblastoma in the United States. Dr. Shields said she and her colleagues and Wills Eye Hospital treat nearly half of those patients.
Parents are commonly the first to notice the whitening of their baby’s pupil, an effect known as leukocoria.
“Even though we are proud that children rarely die of this cancer in the United States, we still have a long way to go,” Dr. Shields said. “We have to better detect this tumor when it is smaller. Our goal in our retinoblastoma practice, similar to our melanoma practice, is to improve detection.”
For more information:
- Carol L. Shields, MD, co-director of the oncology service at Wills Eye Hospital, can be reached at 840 Walnut St., Philadelphia, PA 19107; 215-928-3105; fax: 215-928-1140; e-mail: carol.shields@shieldsoncology.com.
- Daniele Cruz is an OSN Staff Writer who covers all aspects of ophthalmology.