Researchers at Mayo Clinic have developed a blood-based diagnostic method that may improve the detection of germ cell tumours, the most common form of testicular cancer, including cases that standard blood tests fail to identify. The study is published in Nature Communications.
Current diagnosis relies on tumour markers measured in the blood, but some germ cell tumours do not produce sufficient quantities of these markers to be detected, which can delay diagnosis and treatment planning, particularly in younger patients. To address this gap, the research team used immune profiling to analyse thousands of immune system signals simultaneously, developing a new test called GCT-iSIGN.
In a study of 427 blood samples, GCT-iSIGN correctly identified 93% of individuals with germ cell tumours and accurately ruled out cancer in 99% of those without the disease. Notably, the test detected 23 of 24 cases that had returned negative results on standard blood tests, suggesting meaningful added sensitivity in diagnostically challenging presentations.
The team also developed a complementary test, Sem-iSIGN, designed to distinguish between the two primary subtypes of testicular cancer, a distinction with direct relevance to treatment selection, as each subtype may require a different therapeutic approach.
The findings build on prior work by the same group using immune profiling to identify biomarkers associated with paraneoplastic neurologic syndrome linked to testicular cancer, including the KLHL11 IgG antibody, previously described in The New England Journal of Medicine.
The authors note that further studies are required before either test can be used routinely in clinical practice.
Source: Gilligan J. Blood test shows promise for detecting testicular cancer when standard markers miss. Mayo Clinic News Network, 28 April 2026. Nature Communications. DOI: 10.1038/s41467-026-71174-9
Current diagnosis relies on tumour markers measured in the blood, but some germ cell tumours do not produce sufficient quantities of these markers to be detected, which can delay diagnosis and treatment planning, particularly in younger patients. To address this gap, the research team used immune profiling to analyse thousands of immune system signals simultaneously, developing a new test called GCT-iSIGN.
In a study of 427 blood samples, GCT-iSIGN correctly identified 93% of individuals with germ cell tumours and accurately ruled out cancer in 99% of those without the disease. Notably, the test detected 23 of 24 cases that had returned negative results on standard blood tests, suggesting meaningful added sensitivity in diagnostically challenging presentations.
The team also developed a complementary test, Sem-iSIGN, designed to distinguish between the two primary subtypes of testicular cancer, a distinction with direct relevance to treatment selection, as each subtype may require a different therapeutic approach.
The findings build on prior work by the same group using immune profiling to identify biomarkers associated with paraneoplastic neurologic syndrome linked to testicular cancer, including the KLHL11 IgG antibody, previously described in The New England Journal of Medicine.
The authors note that further studies are required before either test can be used routinely in clinical practice.
Source: Gilligan J. Blood test shows promise for detecting testicular cancer when standard markers miss. Mayo Clinic News Network, 28 April 2026. Nature Communications. DOI: 10.1038/s41467-026-71174-9
