Topic: Kidney Stones

Immunotherapy for NMIBC: Emerging and Expanding Indications

Jennifer M. Taylor, MD, MPH, Assistant Professor of Urology at Baylor College of Medicine in Houston, Texas, reviews new indications for immunotherapy for non-muscle invasive bladder cancer (NMIBC). She discusses the most common immunotherapy option, presents active clinical trials, and evaluates new treatment options. AUA guidance has previously stated that immunotherapy should be reserved for highest-risk NMIBC, and that for lower-risk cancer, patients and clinicians should weigh the benefit ratio when considering whether immunotherapy is an appropriate treatment choice given the possibility of adverse events. However, a shortage of the most common intravesical immunotherapy, bacillus Calmette-Guerin (BCG), in combination with increased numbers of BCG-unresponsive patients, have altered the treatment landscape. Dr. Taylor reviews the 2018 definition of BCG-unresponsive NMIBC and identifies several ways to determine whether a patient is BCG-unresponsive. Finally, she discusses the approval of pembrolizumab as a newly-available treatment for BCG-unresponsive NMIBC. In the study that led to the approval, 41% of patients had a complete response and no patients progressed to muscle invasive bladder cancer or metastasis. These favorable results are notable given that the gold-standard alternative is radical cystectomy. Additionally, pembrolizumab is well-tolerated and while adverse immune-related events are serious, they are rare and can be managed. Other treatments are also currently under investigation.

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Guideline-Based Approach to Metabolic Stone Management for the General Urologist

Wesley A. Mayer, MD, Associate Professor of Medicine at Baylor College of Medicine in Houston, Texas, discusses the AUA guidelines for the medical management of kidney stones, also known as nephrolithiasis. There are 27 guidelines, fitting into the categories of evaluation, diet therapy, pharmacologic therapy, and follow-up. Dr. Mayer urges urologists to care for the whole patient, and to not just focus on the surgical issue. Nephrolithiasis is both a surgical and medical disease, making follow-up with these patients essential. For example, urologists can use a metabolic work-up to reduce the risk of future stone formation. Dr. Mayer concludes by reemphasizing that stone management often requires multiple modalities, including diet and medication, and by noting that for complex cases, urologists may want to consider referring patients to a dietician or other expert.

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A Better Mousetrap: Minimally-Invasive Management of Symptomatic Caliceal Diverticular Stones in the Era of Robotic Surgery

Richard E. Link, MD, PhD, Professor of Urology and the Carlton-Smith Endowed Chair in Urologic Education at the Baylor College of Medicine, discusses the pros and cons of different techniques for managing caliceal diverticular stones, a simple problem requiring a complex solution. The presentation aims to provide a framework for the identification and management of this condition since there are not enough high-quality studies to have a definitive strategy. Dr. Link discusses caliceal diverticulum incidence, etiology, and presentation, as well as the specific qualities of stones in caliceal diverticula, noting that stone formation is not caused by the presence of a caliceal diverticulum, but rather by the same metabolic anomalies experienced by other stone formers. He then dissects the different surgical options for treatment, including: extracorporeal shockwave lithotripsy (ESWL), which results in stone-free rates of ≤25% and should only be used in patients who cannot tolerate more effective therapy; ureteroscopic management, which is superior to ESWL but still has low success rates; and percutaneous management, which was the gold standard treatment before the era of robotic surgery, and results in a stone-free rate between 70 and 100%, although it can be a challenging surgery. Dr. Link also discusses laparoscopic diverticulectomy and robotic true partial nephrectomy, more aggressive approaches that may be needed if percutaneous management fails. He concludes with several case studies, emphasizing that treatments should be tailored to individual patients.

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Renal Stones: To Dust or to Basket?

Nicole L. Miller, MD, FACS, discusses the pros and cons of dusting versus basketing renal stones. She evaluates cost, time, safety, and recurrence with both procedures. The benefits of dusting include decreased procedure time, decreased disposables, lower cost, and comparable complications. The benefits of fragmentation and basketing include obtaining stone composition, improved stone-free rates, clear benefits in specific populations, and versatility with laser machines. The goals of a successful stone surgery are maximum efficiency, being stone-free, safety, and lowest cost. Looking at the type of stone and the patient will determine which method is best to use.

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Breaking Bad: Advances in Laser Lithotripsy Techniques

Nicole L. Miller, MD, FACS, Associate Professor of Urology at Vanderbilt University Medical Center, discusses AUA guidelines for the treatment of ureteral stones, and compares and contrasts them to the EAU guidelines, examining several cases to illustrate similarities and differences in treatment approaches. She observes that the EAU guidelines are updated more frequently than the AUA guidelines, which often puts them ahead in terms of pain management. Dr. Miller emphasizes that shock wave lithotripsy (SWL) treatment has the least morbidity and lowest complication rate, but ureteroscopy (URS) has a higher stone-free rate in all ureteral locations. She discusses which special cases would be best treated with URS, and why a ureteral stent is not necessary after uncomplicated URS. Finally, Dr. Miller looks at how multimodal therapy for stent pain can significantly reduce narcotic usage.

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Endourological Stone Management: Complicated Cases

Jens Rassweiler, MD, Professor and Head of the Department of Urology at Klinikum Heilbronn, the academic hospital of Heidelberg University in Germany, discusses the management of complicated cases of endourological stones. First, he defines what exactly makes a case complicated, and then goes on to detail the procedures involved. He compares various management methods, noting the pros and cons of each and emphasizing the importance of staying away from open surgery when possible. He does discuss the best techniques for open surgery when it is unavoidable, but emphasizes that a combination of robotic and laparoscopic surgery is best.

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The Implications of the Microbiome on Stone Pathophysiology, Stone Prevention and Novel Diagnostics

Manoj Monga, MD, and Aaron W. Miller, PhD, discuss the effect of the microbiome of the gut and urinary tract on the development and prevention of stone disease. Dr. Miller discusses research into oxalate metabolism in the gut that can lead to kidney stones, how the bacteria lactobacillus crispatus may reveal clues about metabolites that can help prevent the incidence of stones, as well as a strain of E. coli that may be connected to their increase.

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Surgical Management of Stone Disease

Peter Schulam MD, PhD, discusses the 2016 American Urological Association (AUA)/ Endourology Society guidelines regarding observation of renal calculi, the treatment of ureteral and renal stones, urolithiasis during pregnancy, and the role of open surgery in stone disease. Specifically, he discusses medical expulsive therapy (MET), ureteroscopy, and shockwave lithotripsy (SWL).

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Controversies in Percutaneous Nephrolithotomy

Dr. Manoj Monga, MD, discusses the controversies in PCNL in terms of use of antibiotics; endoscopic-guided access; whether it be prone or supine; which calyx to access; whether to use a small sheath or a large sheath; and what type of tube to leave at the end of the procedure.

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