Dalia Kaakour, MD, MPH, on ctDNA in testicular cancer surveillance

In an interview at the 2026 American Society of Clinical Oncology Genitourinary Cancers Symposium in San Francisco, California, Dalia Kaakour, MD, MPH, presented retrospective data suggesting circulating tumor DNA (ctDNA) may offer a highly accurate tool for detecting residual disease and recurrence in testicular cancer. The findings indicate ctDNA could improve surveillance by outperforming conventional serum tumor markers and, in some cases, imaging.

Kaakour is a hematology and oncology fellow at the University of California, Irvine.

Kaakour explained that testicular cancer primarily affects young men, making long-term surveillance especially important. Current monitoring strategies rely on serum tumor markers such as AFP, bHCG, and LDH, along with CT imaging. However, these markers can be inconsistent, with substantial variability between patients and limited sensitivity in some cases. Repeated CT scans also expose a young population to cumulative radiation, underscoring the need for more precise and less burdensome surveillance methods. Against this backdrop, ctDNA has emerged as a promising biomarker in multiple tumor types, prompting investigators at the University of California, Irvine, to evaluate its role in testicular cancer.

The retrospective chart review included 41 patients treated between 2020 and 2025, encompassing all stages and histologic subtypes of testicular cancer. Investigators analyzed 153 ctDNA samples using a commercially available assay, with nearly equal representation of seminoma and nonseminoma cases. Across 148 evaluable samples, ctDNA demonstrated 100% sensitivity (95% CI 79.4% to 100.0%) and 100% specificity (95% CI 97.2% to 100.0%) for identifying residual disease or relapse, using imaging or pathology as the reference standard. These findings were observed regardless of disease stage or histology, suggesting broad applicability across the testicular cancer population.

Kaakour also highlighted 8 discordant cases in which ctDNA and CT imaging results did not align. In instances where ctDNA was positive but imaging was initially negative, short-interval follow-up scans later confirmed recurrence. Conversely, when imaging raised concern for relapse but ctDNA was negative, subsequent surgery and pathology in select cases showed no malignancy, suggesting false-positive imaging findings. According to Kaakour, these results indicate ctDNA may be both more sensitive and more specific than standard imaging in certain scenarios. She noted that larger prospective studies are needed, but the data support ctDNA as a potentially valuable addition to surveillance strategies for patients with testicular cancer.

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