HMN 2026: How Radiotherapy may spur cancer growth at distant sites in CD14-high tumors

Scientists at the National Taiwan University Cancer Center and National Taiwan University Hospital have shed light on rare but important situations where radiotherapy to one tumor is accompanied by cancer growth or metastasis at untreated sites. Tumors with intrinsically high CD14 expression show increased neutrophil infiltration at baseline. This tumor-intrinsic feature, identified from both patient samples and mouse models, marks a higher risk of radiotherapy being followed by cancer growth or metastasis at distant sites.

Radiotherapy is one of the most commonly used cancer treatments and is highly effective at controlling tumors at the site being treated. In rare cases, however, clinicians have observed a puzzling outcome: After radiotherapy successfully controls one tumor, new tumors may appear at other, untreated locations in the body.

This counterintuitive phenomenon is known as the “badscopal effect.” Unlike the better-known abscopal effect, in which radiation helps the immune system attack tumors elsewhere, the badscopal effect describes a situation where treating one tumor unintentionally promotes cancer growth at untreated sites.

In the new study, researchers investigated why this happens. Focusing on urothelial cancer, the team analyzed patient tumor samples and conducted experiments in animal models. They found that some tumors already carry a high-risk immune environment before radiotherapy begins. Their study is published in the Journal of Biomedical Science.

Specifically, CD14-high tumors are associated with increased neutrophil infiltration, which may create conditions that facilitate cancer cell entry into the bloodstream. Following radiotherapy, this effect may become more pronounced, increasing the likelihood of cancer growth and metastasis at untreated sites. Importantly, reducing neutrophil level or suppressing tumor CD14 expression was associated with a lower risk of this outcome in animal models.

Prof. Yun Chiang and Prof. Jason Chia-Hsien Cheng claim, “Our findings help explain rare but important situations in which radiotherapy to one tumor is followed by cancer growth or metastasis elsewhere, pointing to tumor-intrinsic CD14 as a marker of higher risk, and urge the need to precisely select patients with treatment benefit.”

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