Waterfall Plot in Oncology Trials

 Waterfall Plot in Oncology Trials: 

What is a Waterfall Plot in Oncology?

A waterfall plot is a bar chart commonly used in oncology clinical trials to visually represent tumor response for individual patients. Each bar represents one patient, showing how much their tumor size has changed from baseline after treatment.

Key Features of a Waterfall Plot

  • X-Axis (Patients): Each bar represents an individual patient.
  • Y-Axis (Tumor Size Change, % Reduction/Growth from Baseline):
    • Negative values (below zero) → Tumor shrinking (partial or complete response).
    • Positive values (above zero) → Tumor growth or progression.
    • Bars reaching or exceeding -30% → Meet the criteria for Partial Response (PR) per RECIST (Response Evaluation Criteria in Solid Tumors).
    • Bars reaching or exceeding +20% → Indicate Progressive Disease (PD).

How to Interpret the Y-Axis?

  • The y-axis represents the percentage change in tumor size from baseline.

  • The percentage is calculated as:

    Percentage Change=New Tumor Size−Baseline Tumor SizeBaseline Tumor Size×100\text{Percentage Change} = \frac{\text{New Tumor Size} - \text{Baseline Tumor Size}}{\text{Baseline Tumor Size}} \times 100

  • Typical Interpretation:

    • ≤ -100% → Complete Response (CR) (tumor disappears).
    • ≤ -30% → Partial Response (PR).
    • Between -30% and +20% → Stable Disease (SD).
    • ≥ +20% → Progressive Disease (PD).


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