At Dresden University Hospital, researchers have cracked a longstanding puzzle in cancer care: how to spare colon cancer patients from chemotherapy they don't actually need. In a landmark randomized trial called CIRCULATE, scientists demonstrated that a simple blood test measuring circulating tumor DNA—fragments of cancer shed into the bloodstream—can reliably predict which patients will benefit from follow-up chemotherapy after surgery, and which can safely avoid it.
The stakes matter enormously. After surgery for colon cancer, especially in Stage II cases (intermediate-risk patients), physicians face an agonizing choice. Around one in five untreated patients will suffer a relapse. Yet prescribing chemotherapy to prevent that relapse exposes many patients to significant side effects and burden—treatment that, for many, turns out to be unnecessary. This is where ctDNA comes in. Modern molecular methods can detect these tumor DNA fragments in blood with striking accuracy, potentially transforming how doctors make treatment decisions.
Between 2020 and 2025, more than 2,100 patients across Germany and Austria enrolled in the CIRCULATE study. Researchers measured ctDNA levels after surgery, then randomly assigned patients with detectable ctDNA to either receive chemotherapy or standard observation. The results, presented at the American Society of Clinical Oncology annual meeting and published simultaneously in the Annals of Oncology, were unequivocal.
First, ctDNA proved itself as a powerful prognostic marker: three years after surgery, 87 percent of ctDNA-negative patients remained free of recurrence, compared with only 52 percent in the ctDNA-positive group. But more importantly, the study delivered the first randomized evidence that ctDNA-positive patients actually benefit from chemotherapy. Among treated patients, the three-year relapse-free survival rate was 77 percent with chemotherapy versus just 38 percent without—a meaningful reduction in recurrence risk.
Prof. Gunnar Folprecht, the study's lead oncologist at Dresden University Hospital, explained the dual significance. "We were able to confirm that ctDNA is a clinically significant risk marker. More importantly, we demonstrated that patients who test positive for ctDNA actually benefit from chemotherapy." This opens a path toward precision oncology: patients without detectable ctDNA can forgo chemotherapy entirely, while those testing positive receive targeted treatment tailored to their actual risk.
The implications ripple through the entire care model. Prof. Jürgen Weitz, director of visceral surgery at the hospital and co-author of the study, emphasized that excellence in surgery remains fundamental, but chemotherapy decisions now rest on individual biology rather than blanket protocols. Prof. Esther Troost, Dean of the Faculty of Medicine at TU Dresden, described CIRCULATE as a turning point—translational research transformed into clinical evidence that will shape patient care tomorrow.
Yet enthusiasm must contend with reality. The test used in the study remains unavailable commercially; while alternatives exist, German health insurance providers do not yet cover the costs routinely. Before ctDNA-based decisions can become everyday practice, Folprecht acknowledged, issues of availability and financing must be resolved. At Dresden University Hospital, where the clinical infrastructure and expertise already exist, administrators stand ready to implement these innovations once regulatory and financial pathways clear. The science is solid. Now comes the harder work of making it accessible.