Clinical Trials Day and the importance of structurally recording treatment outcomes
Today, on Clinical Trials Day (May 20), we reflect on the importance of clinical research. For Hartwig, it’s a opportunity to highlight a crucial but often overlooked element in oncology care: the systematic documentation of treatment outcomes in everyday clinical practice.
Only when we understand how patients respond to therapies can we begin to explain why treatments work—or don’t—and feed those insights back into care. A prime example is the (non-)response study by Joris van de Haar, published in Nature Medicine (2021). This study was only possible by combining data from the Hartwig Medical Database genomic analyses with carefully documented response values from a clinical trial.
The research showed that the DNA alterations guiding treatment choices remain remarkably stable, even under therapeutic pressure. This means that a comprehensive DNA analysis, performed at the right moment, can provide lasting value for patient care.

As Joris van de Haar puts it:
“If you map out the full DNA of a cancer patient and their tumor, the differences between the two genomes reveal promising treatment options. DNA errors for which approved drugs exist remained stable during treatment in 99% of patients.”
This highlights the value of a single, in-depth analysis performed early in treatment. But: DNA data alone do not tell the full story. Without knowing how a patient responds to a treatment, we miss the key to interpretation.
It’s like viewing a map of a landscape without knowing which path to take. We see the terrain, but we don’t know which way to go. Fortunately, more and more clinicians are recognizing the value of combining genomic data with real-world treatment and response data. Yet in daily practice, systematic documentation of these outcomes is still lacking—and that means we’re missing valuable opportunities to learn.
Let’s use Clinical Trials Day to advocate for better integration of these insights into everyday care. So that we don’t just continue treating—we continue learning. Even when that learning leads to the shared decision not to treat. Because ultimately, it’s not about more care, but about the right care for every patient
More information
- Limited evolution of the actionable metastatic cancer genome under therapeutic pressure, Joris van de Haar et al
- Clinical Trials Day
- Hartwig Medical Database
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