Treatment of pediatric acute lymphoblastic leukemia (ALL) typically follows a standardised regimen, consisting of several phases of therapy, with a varying number of medications administered during each phase. The Dutch Childhood Oncology Group collects data on many aspects, such as dose, relapse, infection, blood counts and toxicities.
We introduce symptom clusters as a visualization method to summarize and communicate these large amounts of longitudinal data. Symptom clusters have been previously used in a cross-sectional manner to describe the side-effects experienced by cancer patients. Our innovation is to use the symptom clusters in a longitudinal manner, and to visualize them by means of a summary measure. We discuss the method and the choices that need to be made, and the clinical insights that can be obtained from longitudinal visualization of symptom clusters. This is illustrated with data from the Dutch ALL9 protocol.