Dr. Sheaumei Tsai

Dr. Mark A. Preston is a urologic surgeon at Brigham and Women’s Hospital and Associate Professor of Surgery at Harvard Medical School. Dr. Preston received his Medical Degree from the University of Ottawa in Canada, where he also completed his residency training in Urology. He completed a three-year accredited fellowship in Urologic Oncology at Massachusetts General Hospital including a Masters of Public Health from the Harvard School of Public Health with a concentration in clinical effectiveness. He is board certified in Urology.Dr. Preston’s clinical interests include urologic oncology (bladder, kidney, prostate and testicular cancer) and minimally invasive surgery. Dr. Preston’s research focuses on the epidemiology of prostate and kidney cancer risk with an emphasis on predictive biomarkers and pharmacoepidemiology. Dr. Preston is highly rated in 19 conditions, according to our data. His top areas of expertise are Bladder Cancer, Muscle Invasive Bladder Cancer, Prostate Cancer, Cystectomy, and Prostatectomy.

Dr. Alex J. Vanni is an internationally recognized expert in reconstructive urologic surgery and a Professor of Urology at Lahey Hospital and Medical Center, where he serves as Director of the Center for Reconstructive Urologic Surgery. He specializes in complex urethral stricture disease and advanced male genitourinary reconstruction, with a focus on restoring urinary function and improving long-term quality of life through precise, evidence-based surgical care. He completed a fellowship in Reconstructive Urologic Surgery at the University of Washington and brings over 20 years of surgical experience to every case, with success rates consistently exceeding national averages.Dr. Vanni leads one of the highest-volume urethral reconstruction practices in the United States and the busiest reconstructive urology program in New England. Physicians across the country refer patients to Dr. Vanni for his expertise in complex and recurrent disease and his long track record of outstanding surgical outcomes. As President of the Trauma and Urologic Reconstructive Network of Surgeons (TURNS) and a Board member of the Society of Genitourinary Reconstructive Surgeons (GURS), he is actively advancing the field through multicenter research, surgical education, and the development of national standards in reconstructive urology. Dr. Vanni is highly rated in 12 conditions, according to our data. His top areas of expertise are Urethral Stricture, Lichen Sclerosus, Bladder Outlet Obstruction, Reconstructive Urology Surgery, and Endoscopy.

Douglas Dahl is a Urologist in Danvers, Massachusetts. Dr. Dahl is highly rated in 27 conditions, according to our data. His top areas of expertise are Prostate Cancer, Renal Cell Carcinoma (RCC), Familial Prostate Cancer, Prostatectomy, and Nephrectomy. Dr. Dahl is currently accepting new patients.