Laurence Klotz, MD, FRCSC

University of Toronto

Toronto, Ontario, Canada

Laurence Klotz, MD, FRCSC, is a Professor of Surgery at the University of Toronto and the Sunnybrook Chair of Prostate Cancer Research at Sunnybrook Health Sciences Centre in Ontario, Canada. Dr. Klotz was the founding editor-in-chief of both the Canadian Journal of Urology and the Canadian Urology Association Journal (CUAJ), and he is now editor emeritus of the CUAJ. Dr. Kotz’s research interests include active surveillance, micronutrients, and prostate cancer prevention.

Dr. Klotz obtained his medical degree and completed his residency at the University of Toronto in Ontario, Canada. He was also a uro-oncology fellow at Memorial Sloan Kettering Cancer Center in New York.

Dr. Klotz has 550 peer reviewed publications and eight books. He coined the phrase “active surveillance” and successfully championed this approach for men with favorable-risk prostate cancer against substantial resistance. Dr. Klotz received the Queen’s Jubilee Medal for outstanding public service, the University of Toronto's Lister Prize, the Society of Urologic Oncology’s SUO Medal, the American Urological Association’s Richard Williams Award, the University of Toronto's Lifetime Achievement Award, the Canadian Urological Association Lifetime Achievement Award, and the Harold Warwick Award from the Canadian Cancer Society for “outstanding contributions to cancer control.” In 2015 he was inducted as a Member of the Order of Canada, Canada’s highest civilian award.

Talks by Laurence Klotz, MD, FRCSC

Navigating Hormone Therapy in Prostate Cancer: Strategies to Reduce Side Effects and Prolong Survival

Laurence Klotz, MD, FRCSC | Apr 2026

Strategies to mitigate androgen deprivation therapy toxicity while sustaining oncologic benefit.

Micro-Ultrasound-Guided vs MRI-Guided Biopsy for Prostate Cancer Diagnosis (OPTIMUM Trial)

Laurence Klotz, MD, FRCSC | Dec 2025

Dr. Laurence Klotz reports OPTIMUM trial results showing micro-ultrasound is non-inferior to MRI fusion biopsy for detecting clinically significant prostate cancer.

Genomics and Natural History of MRI Invisible vs Visible Cancers: Implications for Clinical Practice

Laurence Klotz, MD, FRCSC | Dec 2025

Laurence Klotz, MD, explains how MRI-invisible prostate cancers differ from visible cancers in both genomic features and clinical behavior. He highlights radiogenomic evidence and long-term clinical outcomes supporting targeted biopsy strategies and reduced reliance on systematic biopsies in prostate cancer management.

Genomics and Natural History of MRI Invisible vs Visible Cancers – Implications for Clinical Practice

Laurence Klotz, MD, FRCSC | Nov 2024

Laurence Klotz, MD, FRCSC, explores the genomics and natural history of MRI-visible versus invisible prostate cancers and their clinical implications.

In this 12-minute presentation, he highlights that while MRI is transformative in identifying significant prostate cancer, it misses about 15% of “invisible cancers.” Recent research reveals that the invisibility of these tumors correlates with favorable genomic profiles, including fewer genetic aberrations and reduced aggressivity.

Dr. Klotz presents compelling evidence linking visible tumors to adverse molecular features and worse clinical outcomes, whereas invisible cancers are largely indolent. He underscores the potential of radiogenomics in guiding treatment decisions, advocating for management strategies based on imaging rather than solely histology.

Dr. Klotz considers avoiding unnecessary systematic biopsies in favor of targeted MRI approaches can minimize patient anxiety and reduce overdiagnosis of insignificant cancers. However, challenges remain in addressing gray areas, such as PI-RADS 3 lesions and visible but low-grade cancers, which may require more nuanced management.

Optimization of Prostate Biopsy – Micro-Ultrasound versus MRI (OPTIMUM)

Laurence Klotz, MD, FRCSC | Nov 2024

Laurence Klotz, MD, FRCSC, introduces the OPTIMUM trial, a landmark international study comparing micro-ultrasound and MRI for prostate cancer detection. In this 9-minute presentation, Dr. Klotz explains that micro-ultrasound, operating at 29 MHz, offers three times greater resolution than conventional ultrasound. Using a PRIMUS scoring system analogous to PI-RADS, micro-ultrasound demonstrates its utility in identifying highly sensitive lesions.

Dr. Klotz details the trial’s three-arm design, which involves MRI with conventional ultrasound, MRI with micro-ultrasound, and micro-ultrasound alone to assess non-inferiority and complementary detection capabilities.

Dr. Klotz emphasizes the trial’s importance for minimizing bias and improving diagnostic practices, particularly given its potential to replace or complement MRI. He highlights the study’s robust design, comprehensive objectives, and international collaboration, anticipating its transformative impact on prostate cancer diagnosis and management.