Michael J. Zelefsky, MD

Michael J. Zelefsky, MD

Memorial Sloan Kettering Cancer Center

New York, New York

Michael J. Zelefsky, MD, is Professor of Radiation Oncology and the recipient of the Greenberg Chair for Prostate Cancer Research at Memorial Sloan Kettering Cancer Center in New York City. He is a board-certified radiation oncologist and co-leader of Memorial Sloan Kettering’s Genitourinary Disease Management Team, a multidisciplinary group of physicians who work together to treat patients with urologic malignancies. As a recognized expert in the field of radiation therapy, Dr. Zelefsky is Chief of Memorial Sloan Kettering’s Brachytherapy Service.

The prostate brachytherapy program at Memorial Sloan Kettering, which Dr. Zelefsky helped develop and enhance since joining the staff in 1990, is known for its depth of experience and cutting-edge approach in treating men with prostate cancer. For patients with advanced or aggressive prostate cancer, he has significant expertise using high-dose-rate brachytherapy and temporary brachytherapy, in which patients receive several high-dose treatments either as a boost or as the sole treatment. Dr. Zelefsky also has experience using brachytherapy in patients whose tumor has recurred after external-beam radiation therapy or seed implant, as well as expertise using image-guided stereotactic radiosurgery for areas of metastases (spread) such as bone or lymph nodes.

In addition, Dr. Zelefsky was instrumental in pioneering the use of IMRT (intensity-modulated radiation therapy, which is computer-guided delivery of high doses of radiation directly to the tumor) and IGRT (image-guided radiotherapy, radiation beams targeted precisely to the tumor) for treating men with prostate cancer. He is Editor-in-Chief of Brachytherapy, a medical journal that addresses all aspects of this sub-specialty. He is also a past president of the American Brachytherapy Society.

For his work in this field, Dr. Zelefsky has been honored to receive several awards including the Boyer Award for Excellence in Clinical research, the Outstanding Teaching Award in the Department of Radiation Oncology at Memorial Sloan Kettering, the 2009 Henschke Medal (the highest award of the American Brachytherapy Society for achievements in Brachytherapy), and the 2009 Emanuel Van Descheuren Award for Excellence in Translational Research.


Talks by Michael J. Zelefsky, MD

Comparative Outcomes: Prostate Brachytherapy vs. EBRT vs. SBRT for Low/Intermediate Risk Disease

As part of a special course on brachytherapy for prostate cancer from the American Brachytherapy Society (ABS) and Grand Rounds in Urology, Michael J. Zelefsky, MD, Vice Chair of Clinical Research in the Department of Radiation Oncology and Chief of the Brachytherapy Service at Memorial Sloan Kettering in New York City, compares outcomes for prostate brachytherapy vs. external-beam radiation therapy (EBRT) vs. stereotactic body radiotherapy (SBRT) for patients with low- and intermediate-risk disease. Dr. Zelefsky explains that when comparing outcomes, the focus is on toxicity after therapy and the efficacy of therapy. He also notes several limitations in comparing different radiotherapeutic modalities as well as dramatic technological innovation over the last 10 years that have greatly improved radiotherapy delivery. While this has been revolutionary in the treatment of disease, it creates what he calls “a moving target” when comparing outcomes because of the difficulty in comparing studies completed at various points in this technological revolution. Dr. Zelefsky cites a comparative study of patient-reported quality-of-life (QOL) outcomes after SBRT, low-dose-rate (LDR) brachytherapy, and high-dose-rate (HDR) brachytherapy for prostate cancer. Another study compared patient-reported QOL following SBRT and conventionally fractionated EBRT compared with active surveillance in those with localized prostate cancer. He reviews highlights from five-year outcomes of the HYPO-RT-PC randomized, non-inferiority, phase 3 trial that examined ultra-hypofractionated versus conventionally fractionated radiotherapy for prostate cancer, including that the estimated failure-free survival at five years was 84 percent in both treatment groups. Dr. Zelefsky notes that genitourinary and gastrointestinal toxicity were similar in both groups as well. He presents a chart illustrating urinary symptoms post-therapy which shows that while LDR has a higher rate of acute grade two urinary symptoms, late urinary toxicity and late urinary incontinence are similar across LDR, EBRT, and SBRT. Dr. Zelefsky outlines the benefits of prostate brachytherapy for favorable and intermediate-risk disease, pointing out that it has the most ablative potential, prostate-specific antigen nadirs are generally significantly lower than with EBRT, and post-treatment biopsy outcomes are positive in just seven percent of patients. He compares this with data showing that EBRT results in post-treatment positive biopsy outcomes of approximately 25-30 percent and data showing that SBRT with a dose of 40 Gy results in post-treatment positive biopsy outcomes of 11 percent. Dr. Zelefsky suggests then that SBRT has more ablative potential than EBRT but that brachytherapy has even more ablative potential than either of these. Finally, Dr. Zelefsky summarizes by explaining how these findings help inform patient decisions and treatment selection, pointing out that prostate brachytherapy may be preferable for the younger patient with few urinary symptoms, while patients with significant urinary symptoms may prefer SBRT. Patients with a larger prostate who may otherwise require downsizing with ADT may opt for SBRT over brachytherapy.

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Precision Radiation Therapy: Low- to Intermediate-Risk Prostate Cancer

Michael Zelefsky, MD, discusses the need for advances in molecular imaging and radiomics and for integrating these techniques with precision radiation therapy in order to improve selective dose delivery for low- and intermediate-risk prostate cancer patients. He describes evolving methods of radiation delivery, dose planning, reducing radiation exposure to normal tissues, and delineation of the dominant intraprostatic lesion in this era of dose-escalation. 

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The Importance of a Post-Treatment Biopsy in the Management of Patients Treated with Radiotherapy for Localized Prostate Cancer

Michael J. Zelefsky, MD, discusses the use of post-radiotherapy prostate biopsy to assess local tumor control following radiotherapy. He argues that post-treatment biopsy can benefit patients by allowing for earlier identification of local recurrences and initiation of salvage therapy than would be possible when relying upon PSA and multiparametric MRI. 

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