A simple blood test may detect tumor relapse in patients with early-stage germ cell tumors

The interim results of the GCC.1 / S1823 study were presented at ASCO 2026 during the Genitourinary Cancer Session. The study focuses on patients with early-stage germ cell tumors and the blood biomarker microribonucleic acid (miRNA) 371a-3p (called miR371). The presence of miR371 may allow clinicians to identify patients at higher risk of relapse earlier and more accurately than current monitoring approaches.

“This trial confirms that a simple blood test for miR371 has high accuracy to detect tumor relapse in patients with early-stage germ cell tumors managed with active surveillance after orchiectomy,” says Dr. Lucia Nappi, the study co-chair who presented the findings at ASCO.

These patients are currently managed with active surveillance and imaging that often can’t distinguish between a benign enlarged node or one that has cancer in it. Using a simple blood test, doctors could more precisely detect the cancer when it comes back or predict the cancer relapse and begin active treatment sooner. 

These results are only the first available of this large clinical trial that enrolled almost 1,000 patients. However, researchers believe that this blood test can detect recurrence in patients with early-stage disease—initial analysis confirms that if the miR371 test is negative, in 90% of the cases there is no tumor. With a follow-up of 37.5 months, only 10 controls (6%) exhibited a false positive miR371 result, confirming an overall specificity of 94%.

"These data support more specific clinical trials, allowing us to understand how to use this biomarker to de-escalate the number of CT scans during active surveillance. It also has potential to decrease the use of chemotherapy in patients who relapse, by diagnosing the relapse earlier,” concludes Dr Nappi.

Although these results are promising, miR371 testing needs further study before being introduced into clinical practice to select patients who need active treatment. Future miR371-informed trials are underway to understand how best integrate the testing in clinical practice. 

"When I was diagnosed, I was offered observation or surgery as treatment options. With support from my care team, I chose surgery because I was uncomfortable with the uncertainty of observation and the repeated radiation exposure from imaging,” says Jonathan, a testicular cancer survivor. “Although the surgery was successful, I later experienced complications that were more difficult than the procedure itself. I’m excited by these findings because a simple blood test may help future patients avoid unnecessary invasive surgery while providing the reassurance that patients deserve."