Scientist Injects Her Own Cancerous Tumor With Viruses She Grew in Lab

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Upon learning she had a breast cancer tumor, a Croatian virologist decided to grow her own viruses to fight the disease — a radical departure from medical norms that appears to have worked.

As the journal Nature reports, the risky self-treatment gambit undertaken by the University of Zagreb’s Beata Halassy has sparked a mix of controversy and admiration among her peers.

The Experiment

After learning in 2020 that she’d had a third recurrence of breast cancer following a mastectomy, Halassy researched oncolytic virotherapy (OVT). This approach uses viruses to combat tumors by triggering targeted immune responses. Although OVT is approved for certain early-stage metastatic melanomas, no government-approved treatments exist for breast cancer anywhere in the world, rendering the self-experiment ethically complex for Halassy, her physicians, and the journal that eventually published her findings.

The virologist enlisted a colleague to administer a combination of the measles virus (commonly used in childhood vaccines) and vesicular stomatitis virus. Both had previously shown an ability to infect the specific cancer cell type she aimed to eliminate while stimulating the required immune activity. Over the two-month trial, the tumor shrank and separated from surrounding muscle and skin, simplifying surgical removal. Post-operative biopsy confirmed that the immune system had indeed been activated against the cancer cells.

“An immune response was, for sure, elicited,” the virologist noted.

Long-Term Outcome and Publication Journey

The treatment took place in 2020. By 2026, Halassy has remained cancer-free for six years. Sharing her results proved challenging. Journal editors repeatedly rejected her paper proposals, citing concerns over the ethics of self-experimentation and the risk that others might attempt similar actions without proper expertise.

Jacob Sherkow, a law and medicine researcher at the University of Illinois-Champaign who was not involved in the study, told Nature that journals must balance the value of knowledge gained from such cases against the danger of presenting them as standard practice. Having studied self-experimentation during the early COVID-19 period, Sherkow believes Halassy’s case “does fall within the line of being ethical, but it isn’t a slam-dunk case.”

Halassy’s paper ultimately appeared in the journal Vaccines in August 2026 under the title “Unconventional Case Study.”

Despite the hurdles, the virologist remains proud of both the experiment and the team that brought it to publication.

“It took a brave editor to publish the report,” Halassy told Nature.

Also read: Doctors reveal why gross shower habit is actually good for us and the planet

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