In Memoriam: Professor Willem M. Star (1938–2026)

In Memoriam: Professor Willem M. Star (1938–2026)

The International Photodynamic Association (IPA) is deeply saddened to announce the passing of Dr. Willem Star, a towering figure in the field of photobiology and a primary architect of modern Photodynamic Therapy (PDT). Willem passed away on March 12, 2026, leaving behind a legacy that transformed PDT from an experimental technique into a rigorous, dose-controlled clinical science.

A Legacy of Scientific Precision

A master of tissue optics, Willem was instrumental in defining the complex relationship between light absorption and scattering coefficients, providing clinicians with the essential tools to predict laser penetration depth within specific tumor types. His practical contributions were equally transformative; he developed and refined specialized, bulb-tipped fiber optic sensors capable of measuring light from all angles within a patient, which proved vital for treating hollow organs like the bladder or esophagus.

Through landmark studies on whole-bladder PDT, he identified the integrating sphere effect, revealing how light can reflect within an organ to cause unexpected over-dosing if not meticulously monitored. Furthermore, his insights into the Implicit vs. Explicit Dosimetry debate helped establish photobleaching as a technique allowing researchers to use the degradation of the photosensitiser itself as a real-time indicator of treatment efficacy. Many of today’s advances in fluorescence-guided therapy and optical diagnostics trace their roots to the foundations he helped establish.

A Foundational Mentor

Beyond his tenure at the Erasmus MC in Rotterdam, Willem was a familiar and respected face at IPA World Congresses for decades, where he will be warmly remembered for the vitality, he brought to the community where Willem was famous for taking to the dance floor. He was known as a meticulous researcher and exacting supervisor who never lost sight of the patient. His seminal 1997 work on in vivo dosimetry remains the gold standard for medical physicists worldwide.

The IPA extends its heartfelt condolences to his family, his former colleagues at the Erasmus MC, and the many scientists around the globe who consider him a mentor. We have lost a true pioneer, but his work continues to guide every treatment plan in our field today.

Written by:

Dominic J. Robinson, PhD
Associate Professor
Department of Otolaryngology, Head & Neck Surgery
Erasmus MC Cancer Institute
d.robinson@erasmusmc.nl