Retinoblastoma risk prediction improved by genetic testing
MedWire News: Incorporating genetic testing into retinoblastoma care via multidisciplinary management ensures timely evaluation and appropriate counseling, and improves risk prediction, say US scientists.
Although retinoblastoma is rare, it is the most common ocular malignant tumor in children. Genetic testing has been available for the RB1 gene for 15 years, and the sensitivity has been steadily increasing as techniques have improved.
The team, led by Sharon Plon from Texas Children's Hospital in Houston, developed a multidisciplinary approach involving pediatric oncologists, an ophthalmologist, an ophthalmic pathologist, a geneticist, and genetic counselors. To assess outcomes associated with this approach, they examined data on 90 initial evaluations over an 8-year period.
In all, 81 children were diagnosed with retinoblastoma, and the remainder were assessed due to a family history of the tumor. Of the children with tumors, 42% had bilateral disease and 58% unilateral tumors, with genetic testing successfully completed in 65% and 62%, respectively.
The most common reason for not achieving genetic testing was failure to keep scheduled appointments, despite multiple attempts. Other reasons included the cost of the test, and the untimely death of four patients, the team notes in the Archives of Ophthalmology.
An RB1 mutation was identified in peripheral blood samples from five of 30 patients with unilateral disease, indicating an hereditary form of retinoblastoma. The occurrence of sporadic retinoblastoma was confirmed in seven of 30 patients using mutation analysis.
Of 48 at-risk parents and siblings of probands attending for initial evaluation from 21 families who underwent genetic testing, six individuals were positive and 42 negative for the familial mutation.
The team says: "Use of a multidisciplinary approach ensures that most patients are evaluated in a timely manner and that all members of the team are aware of implications of the results with regard to cancer risk."
They add: "Aspects of our process that increased the likelihood of completing genetic evaluation included adequate handling of all enucleated eyes with timely freezing of the tumor samples...; institutional billing by the home institution for testing; the presence of genetics professionals with a focus on cancer genetics...; a monthly multidisciplinary meeting with a common clinical database that identified patients who were missed by clinic referral; and provision of the test results, including molecular interpretation and implication for the family, to all team members at the monthly meeting."
By Liam Davenport