Aqueous Humor Is Superior to Blood to Diagnose Retinoblastoma

Retinoblastoma is a cancer that forms in the light-detecting cells in the back of the eye. It often appears in children under two years of age and can lead to blindness or eye removal. Most cancers are biopsied and studied so that medical scientists can design targeted treatments.

When there is a family history of retinoblastoma, a child is most likely to develop the disease within 28 months of birth. When there is no family history, it is frequently the parents who notice the main symptoms of retinoblastoma: a white pupil reflex instead of a normal black pupil or red reflex, or a crossed eye.

Ophthalmologists at the Children's Hospital Los Angeles (Los Angeles, CA, USA) and their associates performed whole genome sequencing on 20 matched blood and aqueous samples. Tumor-associated chromosomal changes were found in 0/20 blood versus 11/20 aqueous samples along with shorter DNA fragments. The scientists concluded that aqueous humor is superior to blood as a liquid biopsy for retinoblastoma.

Jesse L. Berry, MD, Associate Director of Ocular Oncology at Children's Hospital Los Angeles, and senior author of the study, said, “You can't directly biopsy retinoblastoma. The tumor is like liquid and has cells all over the eye. Plus retinoblastoma cells can spread easily. Direct biopsy can cause relapse or spread of the disease outside of the eye. This makes diagnosis tricky. In the absence of molecular tests, trained ophthalmologists must look for anomalies in the eye and use ultrasound imaging to diagnose the disease.”

Dr. Berry noted that “Many children actually have retinoblastoma tumors in both eyes. If we were to test the blood and find a positive result, we would not actually know which eye it was from. Instead, aqueous humor biopsies give us specific information for tumors in each eye. Not only can tumor DNA be detected, but the study also showed that genetic factors can predict treatment success for a given tumor. Taken together, the discoveries are set to drastically improve retinoblastoma research and clinical practice.”

"Aqueous humor biopsy has potential to becoming the new standard of care for retinoblastoma," said Dr. Berry. "It is our best chance to diagnose and treat these patients on a molecular level.” The study was published on October 30, 2019 in the journal Ophthalmology.

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Children's Hospital Los Angeles