Mass. General Cancer Center Radiation Oncologist, Dr. Helen A. Shih, MD talks about treating melanoma in the eye with proton therapy.
Interview conducted by Ivanhoe Broadcast News in 2022.
What are some of the early symptoms of melanoma? Is it obvious to a person who’s having problems?
SHIH: About half the time people are diagnosed from routine eye exams. It is very important to get dry exam every year, a dilated eye exam. For those patients who present with symptoms, oftentimes they just noticed there’s new flashing lights, floaters that are unusual, areas that they can’t see. Any particularly acute sudden changes through their visions are triggers.
Prior to proton therapy, how did you treat ocular melanoma?
SHIH: Ocular melanoma historically was treated by enucleation, meaning the removal of the eye surgically, taking out the entire eye. Cosmetically, that was always- that still is a very challenging situation, and you would also lose function of the vision and the eye. The advent of being able to apply radiation. There are multiple forms, but the first patient treated with proton radiation was in 1974 about 50 years ago, and the advent of using proton radiation to treat ocular melanoma was revolutionary because it allow us to save the eye and save vision. For both for functional and cosmetic reasons, it was a wonderful advancement.
Can you describe what proton therapy is?
SHIH: Proton therapy is a type of radiation therapy. It is relatively scarce still, although it’s increasing in its axis across the country and world. What we do is we coupled the actual radiation, which is a bundle of energy, with little proton particles. Protons are positively charged particle.
For one of your patients, how does this work?
SHIH: The simplest element on the periodic table is hydrogen, which has one electron and one proton. If you strip away the electron, you have protons, which is just the nucleus of the hydrogen atom. We use magnets to accelerate a purified beam of protons. By accelerating protons, we are coupling radiation energy with little particles. The difference between this and most radiation therapies that we use to treat people, is that the particle with charge allows us to control it better. We could control it based on its charge using magnets. Its mass has a certain interaction with tissues and travels a limited distance and stops in tissues. By doing that, we can eliminate or significantly reduce the amount of scatter radiation to the rest of the tissues around which we’re treating. By treating an ocular tumor, with proton radiation, we typically go through the white of the eye, which is fairly resistant to the radiation. It treats the tumor and the beam stops there. There is no radiation or virtually no radiation delivered to the brain, which is very different to any photon radiation generated from a similar type of machine. There always a beam that would go into the eye but also exit out beyond into the brain.
What is the benefit?
SHIH: The benefit of proton radiation can be two folds, but the primary one is reducing the side effects from radiation. As cancer is more and more a collective disease of survivorship. People get treated and they move on with their lives. Side effects are a big deal. We want to be able to reduce the additional negative impact on people’s quality of life so they can go back to living as normally as possible.
Can you save the eye?
SHIH: Usually. The overwhelming majority of people that we treat do not only save their eye, we save their vision.
Considering that just a few years ago the only option was to lose the whole eye, that’s a tremendous benefit to people. Why is it still relatively scarce?
SHIH: Proton therapy in itself is a complex technology. It requires a significant up-keeping in terms of financial cost, as well as expertise. To be able to bring that all together, always multiple millions of dollars of investment. Is challenging to make that commitment.
For whom is this the best option?
SHIH: For the ocular cancer patients, if your tumor is too large, it’s not ideal for actually any radiation because too much radiation delivered to the eye will make the eye nonviable. It has to be limited to a certain part of the eye. If too much of the eye is involved with the tumor, these patients do need to have eye removed or enucleated.
Are there any other parts of treatment? Is it just the radiation? Is radiation in combination with drugs?
SHIH: For this specific tumor type, the most common, we usually treat them with the radiation alone. Increasingly for those patients where it may have metastasized or spread beyond the eye, increasingly, there is a huge role working with medical oncology for systemic therapies to make metastatic disease all the much more a chronic disease, if not hopefully a curative disease in the future.
If the cancer does happen to come back, is this the treatment where you can treat it again with proton therapy or is it a one and once you’ve had the treatment?
SHIH: atahere is a general belief that once you get radiation once to a specific site, you shouldn’t do it again. You can. For the few patients that do recur in the eye, we can retreat them partly because the area that we’re treating is so small, tiny, and localized.
How long has this been an option for patients?
SHIH: The option of proton therapy for ocular melanomas has really been an option for over 45 years, but not known to much of the field even within medicine to other oncologists or ophthalmologists. It’s much better known in the last 20 years. There are also other treatment alternatives in terms of radiation therapy delivered in conjunction with ophthalmologists and oncologist as a little plaque or a wafer known as brachytherapy in the places that are radioactive wafer on the surface of the eye for a few days and then removed. That is perhaps the most common form of radiation treatment or definitive treatment for these tumors because so much more accessible.
And the brachytherapy is that also done in conjunction with the proton therapy?
SHIH: They’re two separate kinds of radiation treatment. We also have treated some patients with that here but our primary modality has been with proton radiation.
Is there anything you want viewers to know? Either about this cancer or about proton therapy?
SHIH: With regards to ocular melanoma, time is of essence. If you have symptoms you want to be seen as soon as possible. Our ability to cure the tumor in the eye is over 90 percent. But there is a risk of it’s spreading to the rest of the body and the treatments are not as successful. For this reason, we want to get it as diagnosed as soon as possible. With regards to our program here at Mass General Hospital and Mass Eye and Ear, we have treated over 5,000 patients with ocular melanoma over the last almost 50 years. In terms of looking for centers of excellence who know this disease well that is relatively rare, it’s not a rare entity here. We certainly welcome patients to reach out to us either for help directly here or to help direct them to a resource more accessible to them.
Have the cases been going up with ocular melanoma?
SHIH: I’m not aware of the incidents of ocular melanoma going up because of the longevity of our program in history and increasing awareness of proton therapy over time. We treat about a quarter of the ocular melanomas in the country at our center.
How many centers in the United States have the proton?
SHIH: There are approximately 40 centers across the US that offer proton therapy. There is only a few other centers that have proton therapy adapted to treating ocular melanomas.
How do you have to adapt it? How much more specialized do you have to be?
SHIH: There’s two unique aspects of treating ocular melanomas compared to other cancer types. It is very small and much easier to treat particularly as proton therapy, larger things. It can be tricky to treat something very small and localize it. Then the eye is a very unique organ because it moves. We have patients who work with us in our treatment. We have them look at a marker or light that we can best design radiation beams to come in through the white of the eye. We make live adjustments in real time based on how setup looks and that is very unique compared to other anatomical sites.
So, patients are awake and you’re telling them please don’t move?
SHIH: Please look at this spot and don’t move for a few minutes. That is correct.
What happens if they blink just normal eye?
SHIH: We put an eyelid retractors each day for radiation treatment. We do numb up the eye ahead so it’s not uncomfortable. It is just for a few minutes because not being able to blink causes your vision to cloud. We work very quickly once we position the patient and then they’re in the right setup for treatment. We then place the eyelid retractors and we do have a few tips and tricks on how to help patients because frequently their vision is already significantly blurred or impaired as a result of the tumor. There are ways that we can direct people to work with us and coach them. Certainly, there’s a variety of clinical challenges.
And vision for most patients after treatment? Is it 20/20?
SHIH: Vision preservation has everything to do. It’s like real estate. If the tumor happens to be located somewhere on the side of the eye, frequently most people retain most of the useful vision. If the tumor happens to be directly back of the eye where all the information eye converges to one spot that goes into the optic nerve, the nerve that takes the information from the eye to the brain. If it’s right over that area in the back most of the eye, frequently they will lose vision. It’s not all or nothing always. It’s not like surgery where you take out the eye and there’s zero vision when you wake up. The loss of vision can be gradual over months even few years. Sometimes it’s partial blurring and some parts of the vision is still clear. Sometimes there’s only one section where the vision is missing and other areas that are clear. We work to best preserve vision as best possible and it’s individualized to each patient.
Can cancer advance when you don’t get the treatment?
SHIH: One Hundred percent. This is a highly curative of cancer if you can catch it early. It’s unfortunately highly non curative cancer if it spreads beyond. That really bleeds right into the advancements that the medical oncology melanoma group have made huge strides in terms of targeted therapies, immunotherapies that work on melanoma. It is better to catch it early so we don’t have to go for additional treatments.
END OF INTERVIEW
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