William L. Diehl specializes in the evaluation, diagnosis and treatment of breast cancer and other diseases of the breast. Dr. Diehl is a breast surgeon and surgical oncologist with extensive experience in the field of breast cancer and breast diseases. He trained at the prestigious Memorial Sloan-Kettering Cancer Center and personally treats over 200 new breast cancer patients a year.

Dr. Diehl was among the first surgeons to perform sentinel node mapping, a technique to identify the spread and stage of breast cancer, helping to determine the best therapy while limiting the amount of surgical trauma to the patient. He is an expert in minimally invasive breast biopsy techniques such as Stereotactic and Ultrasound guided biopsies. He is a strong proponent of breast preserving surgery and other cosmetically enhancing procedures for the treatment of breast cancer such as nipple sparing mastectomies, immediate reconstruction and oncoplastic procedures to provide an optimal surgical treatment while simultaneously utilizing the skills of his plastic surgery colleagues to optimize symmetry and cosmetic improvements.

Dr. Diehl is a member of the American College of Surgeons, the American Society of Breast Surgeons, the American Medical Association, the Medical Society of New Jersey and the Morris County Medical Society. He currently serves as director of the Breast Care Center at Summit Health where he oversees the delivery of breast Health Services for patients. Previously, Dr. Diehl was a member of the New Jersey department of Health/Medical Society of New Jersey Breast Imaging Options Work Group that advised the Governor and the Commissioner of Health on breast imaging and treatment to help establish legislative policy. He has also served as the Medical Director of Saint Clare's Hospital Women's Breast Health Care Center and as the director of the Morristown Medical Center multi-disciplinary Breast Cancer Panel. Dr. Diehl is a past president of the Morris County Medical Society and American Cancer Society Morris unit.

With a passion for teaching, Dr. Diehl is active in the training of young surgeons at Morristown Medical Center, and a recipient of the John Alkhas Teaching Award. He also received the Sharing Village 2007 annual Humanitarian Award and is a co-founder of the nonprofit organization UHMLA, which provides Surgical Services to underserved patients in Latin America. Twice a year he assembles a group of surgeons, nurses and anesthesiologists to travel to Central and South America to perform surgery on patients who would otherwise not have access to health care.

Dr. Diehl is featured in New Jersey Monthly’s ‘Top Doctors’, Inside Jersey’s ‘Top Cancer Doctors’, and Castle Connolly’s ‘Best Doctors in America’, ‘Top Doctors in the New York Metro area’, and ‘America’s Top Doctors’ listings, which have been reported in U.S. News and World Report. Additionally, he has been featured in Inside Jersey’s ‘Top Doctors for Women's Health’ listing for his expertise in breast cancer surgery.