Applying RAPNO Criteria with Clinical Judgment in PLGG

In this segment, Dr. Abdelbaki and Dr. Margol examine the practical limitations of applying RAPNO (Response Assessment in Pediatric Neuro-Oncology) percentage-based progression criteria outside of clinical trials.

Dr. Abdelbaki poses a concrete scenario: A tumor shrinks from 10 cm to 1 cm on therapy, then grows from 1 cm to 1.3 cm—technically meeting the threshold for progressive disease despite an excellent overall response. He asks Dr. Margol how she navigates these limitations.

Dr. Margol echoes Dr. Chi's earlier comments, stating that objective measures and strict definitions of progression and response are necessary for clinical trials, but applying percentage-based cutoffs in routine care is "very tricky." A 26% increase in a small tumor may not be clinically meaningful, and a tumor that grows from 1 cm to 2 cm after shrinking from 5 cm raises questions but does not automatically mandate a treatment change. She emphasizes the importance of common sense and remembering the underlying tumor biology.

In the next episode, "Defining Radiographic Progression, Preserving Vision, and Strategic Use of Treatment Lines," the panel discusses the challenge of defining true progression in PLGG and preserving vision across multiple lines of therapy.