By Timothy Fuller, MD, Ocular Oncologist
With the diagnosis of ocular (uveal) melanoma comes the very real risk of metastatic disease, or “spread” of the cancer to other parts of the body.
In general, about 50% of patients with uveal melanoma go on to later develop metastatic disease. At the time of diagnosis, there is a very small chance (less than 2%) that a patient will already have detectable metastatic disease. To help better monitor for spread of the cancer, and to help a patient better understand their risk for metastatic disease, a fine needle biopsy is typically done at the time of plaque radiation treatment. Unlike a “traditional” biopsy, this sample is not taken to determine what cancer the patient has. Almost always for uveal melanoma, the diagnosis at time of treatment is not in doubt. The Collaborative Ocular Melanoma Study (COMS), a randomized controlled trial evaluating the outcomes of choroidal melanoma treated with plaque radiation or enucleation (eye removal), of which Texas Retina was a part, showed us that over 99.5% of the time the diagnosis is correctly made from clinical exam, imaging and ultrasound findings. Accordingly, a biopsy for obtaining pathology is not required.
So then, WHY is a biopsy taken if the diagnosis is not in doubt?
The biopsy performed at time of radiation treatment is to enable us to learn the “activity level” of the cancer, or the mutations within, otherwise known as a “Genetic Expression Profile” (GEP). In many ways, GEP has supplanted the “older” paradigm of stratifying metastatic risk based on tumor size.
The GEP can come back as low (Class 1A), intermediate (Class 1B), or high risk (Class 2). Patients who are high risk, or Class 2, are referred to a medical oncologist for metastatic screening follow up, as they usually require more rigorous surveillance. At Texas Retina Associates, we partner with the physicians of Texas Oncology, including Katherine Wang, MD, PhD, in Dallas; Charles (Lance) Cowey, MD, in Dallas; and Jessica Hals, DO, in Weatherford, among several other very talented and experienced medical oncologists. Class 1A and 1B patients have the option of referral to a medical oncologist, but if they prefer, they can perform screening with their primary medical physician if he or she agrees.
To learn more about Genetic Expression Profiling, see Castle Bioscience’s website: https://castlebiosciences.com/products/decisiondx-um/
And HOW is the biopsy taken?
Immediately before placement of the radiation, while the patient is comfortably under anesthesia, a very tiny needle is used to aspirate (think of it like a tiny vacuum) cellular material from the tumor. Only a miniscule fragment of sample is needed to get a read. In fact, only 4% of the time is the sample unable to be read (i.e., not yield a result). As with any eye surgery, there is risk, including bleeding, infection, loss of vision and retinal detachment. The very low risk is normally considered to be outweighed by the potential benefit by most patients, medical oncologists and ocular oncologists. In general, very small and/or thin tumors are considered to have more risk from biopsy and/or higher rate of sampling without a read, or “result.”
Be sure to ask your ocular oncologist about genetic expression profiling and whether it makes sense for you.
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