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Advances in molecular diagnostics in the last 15 to 20 years have moved fine-needle aspiration biopsy (FNAB) beyond mere diagnosis of uveal melanoma and into the realm of personalized prognosis. Old-school biopsies seem simplistic in comparison, with their verdicts of benign or malignant and their basic information on cell type and proliferative potential. Today, cytopathologists can figuratively drill down to the intricacies of a patient’s DNA and RNA, looking for clues to treatment and patient management.
“The biopsy techniques have been around for more than 30 years, and some minor refinements have been made over time. But now we have the technology and the methods to analyze the cells and look at their DNA and RNA,” said Arun D. Singh, MD, professor of ophthalmology and director of ophthalmic oncology at the Cleveland Clinic.
These new capabilities are opening doors to patient-specific monitoring and treatment: Patients at high risk may receive high-intensity surveillance and adjuvant therapy, while those whose molecular profiles predict a more indolent course may opt for close surveillance only.
Assessing Metastatic Potential
J. William Harbour, MD, professor of ophthalmology at Washington University School of Medicine in St. Louis, said the two primary reasons for obtaining an FNAB are diagnostic uncertainty and, increasingly, the need for prognostic guidance.
Diagnosis. “About 95 percent of the time, an experienced ocular cancer specialist can diagnose melanoma by just looking at it and performing an ultrasound and other diagnostic tests,” Dr. Harbour said. “We are very accurate at diagnosing melanoma most of the time, but occasionally we will see a tumor that has an appearance that doesn’t quite fit with what you would expect for a melanoma. FNAB might be used in this setting to establish a diagnosis.”
Prognosis. An increasingly compelling reason to perform FNAB is the need to assess a patient’s prognosis in order to design an appropriate treatment plan. The prognostic information that can now be gleaned from an FNAB sample also helps determine the frequency of surveillance and testing for each patient.
Dr. Harbour’s group developed a molecular test that simultaneously measures the expression of 15 genes and is performed using polymerase chain reaction (PCR) on a microfluidics platform that allows extremely small amounts of RNA to be analyzed. “This assay allows a very small number of tumor cells from a needle biopsy to be analyzed with great precision, such that the biopsy can be performed more safely with a smaller needle using a less aggressive technique,” Dr. Harbour said. “Other techniques are available for measuring chromosome gains and losses. These are not as accurate as the gene expression assay, but they are the preferred technique in Europe at the present time.”
Results from the gene expression assay are used to differentiate patients who have a low risk of metastasis (class 1 patients) from those who have a high risk (class 2 patients). “In our practice, a patient with a class 2 profile receives an MRI of the liver twice a year and blood work twice a year,” Dr. Harbour said. “We alternate the tests so that the patient is receiving one or the other every three months.”
Treatment. Patients who have metastatic disease are referred to a medical oncologist and an interventional radiologist for hepatic arterial chemoembolization. This treatment temporarily slows the passage of blood through the liver, allowing the infused chemotherapy to concentrate there for a period of time before it washes through.
“We have had good results with this, especially when we find the metastatic disease early,” Dr. Harbour said. “Patients respond very well, and we are confident that we are extending their lives when we detect metastasis at an early stage while it is still limited.” When chemoembolization no longer works, Dr. Harbour’s medical oncology colleague enrolls the patient in a clinical trial utilizing the best available agent.
Increasing patient surveillance. Researchers believe that stepped-up surveillance is critical to improving the survival of patients with uveal melanoma. Dr. Harbour noted that CT scans are taken when the eye tumor is diagnosed, but only 2 to 4 percent of patients have detectable metastases at that time. “Yet if they live long enough, as many as half of these patients will develop metastatic disease,” Dr. Harbour said. “Presumably, the disease was dormant in a micrometastatic state that we couldn’t detect. But with this new assay technology, we can tell patients with about 95 percent accuracy whether or not they already have microscopic metastatic disease that will later manifest as overt metastasis.”
Knowing metastatic risk. Identifying patients who are at high risk of metastasis enables physicians to follow them more carefully and more frequently with ultrasound and MRI, as well as with blood work to monitor liver status. Dr. Harbour added that identification of high-risk patients could also reduce health care expenditures. “Instead of conducting high-intensity surveillance on every patient with uveal melanoma, we would only need to screen the approximately 40 percent of patients who have an ominous prognostic signature.”1 This increasing ability to predict a patient’s long-term outcome requires frank doctor-patient discussions. But in Dr. Harbour’s experience, when patients are given the option, most want to know their prognosis.
Conducting genetic research. In the meantime, Dr. Harbour’s group has found a gene mutation that is closely associated with the class 2 gene expression profile.2 “The mutated gene—called BAP1—is located on chromosome 3 and plays a role in metastasis,” he said. “Knowing a specific gene that is involved in metastasis allows us to examine the gene and consider how we might develop a drug that would reverse the effects of the mutation.”
Using agents to slow metastasis. Dr. Harbour noted that a class of agents called histone deacetylase (HDAC) inhibitors has shown an ability to slow the growth of micrometastases. “These agents inhibit the growth of melanoma cells and push them to differentiate and become more like normal cells. They might be useful in an adjuvant setting to slow the growth of eye tumors, but not as useful in advanced disease. An advantage of HDAC inhibitors is that they are readily available, well tolerated, and taken orally.” Said Dr. Harbour: “Within a year, we hope to be able to put patients into an adjuvant trial of this targeted oral agent. We are not quite at the adjuvant trial stage yet, but we are very close.”
|Contraindications and Complications
|Contraindications. Although it’s important to know when to perform FNAB, it’s also crucial to know when not to do it. Dr. Singh noted that FNAB should not be used in the following situations:
- In children because of the possibility that a tumor might be a retinoblastoma, and biopsy may lead to tumor seeding outside the globe.
- When the physician is unable to see clearly into the eye because of a retinal detachment or hemorrhage because in such cases it may be difficult to precisely guide the needle into the tumor.
Complications. Potential complications of FNAB are vitreous hemorrhage, subretinal hemorrhage, retinal detachment, and tumor seeding along the needle tracks.
- When a cytopathologist is not available.
FNAB for Orbital Tumors
Dr. Singh noted that Scandinavian orbital surgeons are much more likely than U.S. surgeons to use FNAB to diagnose orbital tumors. The anatomy is challenging, and deep lesions can be accessed only through precise placement of the needle for angle and depth. Moreover, delicate peripheral nerves and blood vessels traverse the orbit, and small compartments of fat limit the surgeon’s view. FNABs of orbital tumors may be performed by an ophthalmologist, a cytopathologist, or an interventional radiologist; but the key to safety and success is an in-depth understanding of orbital anatomy.
Stefan Seregard, MD, PhD, professor of ophthalmology at the Karolinska Institute in Stockholm, noted that core needle biopsies provide a larger sample than fine-needle biopsies but have a much higher complication rate. As a result, core biopsies are rarely used in the orbit. When used together with immunohistochemistry, flow cytometry, and molecular genetics workups, FNAB in the orbit approaches a diagnostic accuracy of 99 percent, he said.
Benefits of FNAB. Dr. Seregard noted several benefits of FNAB. It can identify tumors such as lymphoma that are best treated nonsurgically—thereby eliminating unnecessary surgery and associated trauma to the tumor. In cases where surgery is being considered, orbital FNAB will provide the surgeon with valuable information before a major procedure is undertaken. And compared with incisional biopsy of lacrimal gland carcinoma, for example, FNAB reduces the risk of local tumor spread.
A caution. However, Dr. Seregard also noted that orbital FNAB may be less well suited for a lesion like cavernous hemangioma because the procedure could cause a hemorrhage. This could result in red blood cells and endothelial cells being detected by FNAB, potentially confounding the diagnosis.
Cytopathologists Are Pivotal
According to Dr. Singh, cytopathologists are the unsung heroes of modern-day cancer management. A biopsy is only as good as the people who prepare it, handle it, and interpret it—and without an experienced cytopathologist, the entire process breaks down. “Every hospital in the United States has pathologists but not always a cytopathologist who is experienced in looking at eye tumors,” he said. “Without an experienced cytopathologist, the biopsy is useless.”
Cytopathologists have their own techniques for handling samples, Dr. Singh said. And different labs use different machines; how you need to handle the sample depends on the machine they are using. Dr. Singh stressed the importance of communicating with the cytopathologist ahead of time to obtain clear instructions on how to handle and send the sample, and to get information about how they will process it.
He also offered some practical advice to help surgeons get the best intraocular sample:
- Avoid small tumors (less than 2.5 mm in height).
- Do not use a thinner needle (such as a 30-gauge needle) because cellular yield is low.
- Avoid dry smears (instead, rinse the needle into a transport medium, flushing the contents of the needle and syringe several times).
- Practice on enucleated globes to become familiar with the techniques.
- Always work with an experienced cytopathologist.3
1 Onken MD et al. Ophthalmology. 2012 Apr 20. [Epub ahead of print]
2 Harbour JW et al. Science. 2010;330(6009):1410-1413.
3 Singh AD et al. History, indications, techniques, and limitations. In: Biscotti CV, Singh AD, eds. FNA Cytology of Ophthalmic Tumors. Basel: Karger; 2012:1-9.
Dr. Harbour and Washington University receive royalties based on a license to Castle Biosciences. Drs. Seregard and Singh report no financial interests.
Learn More in Chicago
|On Monday, Nov. 12, at the Joint Meeting, check out Practical Ocular Oncology for the Comprehensive Ophthalmologist (2 to 3 p.m., event code “385.”) You will need an Academy Plus course pass.