Icahn School of Medicine at Mount Sinai Archives

Physics of Intraoperative Dose Planning for Focal Brachytherapy

Posted by Ren-Dih Sheu, PhD, DABR | Nov 2023

Ren-Dih Sheu, PhD, DABR, presents an overview of intraoperative dose planning for focal brachytherapy in prostate cancer treatment. He begins by presenting the two most common options for Focal Radiotherapy: Brachytherapy using LDR Seed Implants and EBRT using Stereotactic Radiosurgery (SRS). He compares the reaction dose fall-offs for each treatment, demonstrating Brachytherapy’s faster radiation fall-off compared to EBRT, despite its higher initial radiation dose.

Dr. Sheu then lists the steps for determining the initial dose and other patient-specific factors affecting the implementation of focal brachytherapy. He highlights factors associated with late local failure and increased patient mortality, emphasizing the importance of high Biologically Effective Doses (BEDs) in preventing recurrence.

Dr. Sheu provides the audience with the equations for determining appropriate BED in Brachytherapy and EBRT patients. Finally, he covers techniques for limiting radiation damage to the patient.

Identifying Mutations and Optimizing Use of PARP Inhibitors

Posted by William K. Oh, MD | Nov 2023

William K. Oh, MD, highlights the growing significance of precision medicine and the role of genetic profiling in tailoring therapeutic strategies. Dr. Oh begins by outlining the importance of identifying DNA repair gene mutations, particularly BRCA1 and BRCA2, in prostate cancer patients. These mutations, which impair the cell’s ability to repair DNA damage, render the cancer more susceptible to treatments targeting DNA repair mechanisms, such as PARP inhibitors.

Dr. Oh delves into the mechanisms of PARP inhibitors, which function by inhibiting the poly (ADP-ribose) polymerase (PARP) enzyme involved in DNA repair. By blocking this pathway, PARP inhibitors induce synthetic lethality in cancer cells harboring defective DNA repair genes, leading to cell death.

Dr. Oh discusses the importance of patient selection based on genetic profiling and the potential for combining PARP inhibitors with other therapies, such as androgen receptor signaling inhibitors and immune checkpoint inhibitors, to enhance their efficacy. He reviews ongoing clinical trials exploring these combination strategies and their preliminary results.

Cardiovascular Side Effects of Advanced Disease Therapies

Posted by William K. Oh, MD | Nov 2023

William K. Oh, MD, details the common therapies used in advanced prostate cancer, including androgen deprivation therapy (ADT), novel hormonal agents like abiraterone and enzalutamide, and chemotherapies such as docetaxel. He emphasizes that while these treatments are effective in controlling cancer progression and improving survival, they have significant cardiovascular risks.
The lecture presents evidence from multiple studies demonstrating that ADT is associated with an increased risk of cardiovascular events, including myocardial infarction, stroke, and sudden cardiac death. Dr. Oh discusses the underlying mechanisms, such as metabolic changes, increased insulin resistance, and adverse lipid profiles induced by hormone deprivation.
Dr. Oh emphasizes the importance of a multidisciplinary approach in managing patients undergoing these treatments. He advocates for regular cardiovascular monitoring, risk assessment, and the involvement of cardiologists in the care team to mitigate these risks.

Adjuvant-Salvage Radiotherapy Following Prostatectomy

Posted by Richard G. Stock, MD | Oct 2023

Richard G. Stock, MD analyzes adjuvant and salvage radiotherapy following prostatectomy in prostate cancer patients with high-risk features or biochemical recurrence post-surgery. Adjuvant radiotherapy is administered shortly after prostatectomy in patients with adverse pathological features, such as positive surgical margins or seminal vesicle invasion, aiming to eradicate microscopic residual disease. Salvage radiotherapy is employed in response to a rising prostate-specific antigen (PSA) level indicating biochemical recurrence after an initial period of undetectable PSA post-surgery.
Dr. Stock reviews pivotal clinical trials and studies, including the SWOG 8794, EORTC 22911, and ARO 96-02 trials, which have demonstrated the efficacy of adjuvant radiotherapy in improving biochemical progression-free survival and overall survival in patients with high-risk features. He highlights the long-term benefits of early intervention with radiotherapy, emphasizing its potential to prevent metastatic progression.

Transperineal Fusion Biopsy

Posted by Michael A. Gorin, MD | Oct 2023

Michael A. Gorin, MD, discusses transperineal fusion biopsy as a viable alternative to transrectal prostate biopsy and its complications. He emphasizes the gravity of the risk of infection, given the large number of prostate biopsies performed.

Dr. Gorin then displays American Urological Association (AUA) recommendations for infection avoidance, highlighting the strategy of transperineal biopsy. He explains that the European Association of Urology (EAU) recommends transperineal biopsy as the first choice for infection avoidance, citing data from a meta-analysis that show a decrease in complications with transperineal biopsies versus transrectal biopsies by more than half.

Further, he shares data showing improved detection of anterior tumors with transperineal biopsy and explains the positioning of the biopsy cores in transperineal biopsy is superior to that of transrectal biopsy. Dr. Gorin shares further data illustrating improved cancer detection with transperineal biopsy before turning to methods of performing transperineal prostate biopsy.

Dr. Gorin addresses magnetic resonance imaging (MRI) targeting, explaining that as of 2020, the AUA endorses the use of pre-biopsy MRI. He displays data showing improved cancer detection with MRI-targeted biopsy and addresses cognitive fusion and explains that a lack of mapping cores is a drawback but explains that today, there are many options for transperineal MRI/transrectal ultrasound (TRUS) fusion prostate biopsy that include grid, mini-grid, and freehand elements.

Dr. Gorin concludes that transrectal prostate biopsy carries a significant risk of infectious complications and transperineal prostate biopsy reduces these risks and can be performed under local anesthesia. Additionally, multiple systems are available to perform transperineal prostate biopsy with TRUS/MRI fusion.