Dr. Annie Callahan is a board-certified surgical oncologist and general surgeon with extensive experience in complex cancer care and community-based surgical practice. She currently serves as a Surgical Oncologist with South Bay Surgeons in Torrance, California, a position she has held since February 2025, where she provides surgical oncology and general surgery services across three high-volume community hospitals in the Los Angeles area.

Dr. Callahan earned her Bachelor of Arts in Anthropology/Biology from Mount Holyoke College, graduating magna cum laude in May 2002. She received her Doctor of Medicine degree from the University of Virginia School of Medicine in May 2008. She completed her general surgery internship (2008–2009) and residency (2009–2014) at Harbor–UCLA Medical Center in Torrance, California, where she was named Chief Resident of the Year in 2014. She subsequently completed a fellowship in Complex Surgical Oncology at City of Hope Comprehensive Cancer Center in Duarte, California, from July 2014 through August 2016.

Prior to her current role, Dr. Callahan served as a general surgeon at Kaiser Permanente in Downey, California, from July 2023 through October 2024. From January 2017 to May 2023, she practiced as a surgical oncologist with Allina Health Surgical Specialists in the Minneapolis–St. Paul region. During this time, she held multiple leadership roles, including Chair of the Department of Surgery at Abbott Northwestern Hospital from January 2020 to 2022 and Medical Director of the Piper Breast Center from 2019 to 2021.

Dr. Callahan is board certified in General Surgery by the American Board of Surgery, initially certified in November 2014 and recertified in October 2025. She is also board certified in Complex Surgical Oncology, with certification issued in January 2017. She holds an active California medical license and is a Fellow of the American College of Surgeons.

An accomplished clinician-scientist, Dr. Callahan has authored and co-authored numerous peer-reviewed publications and has presented her research nationally at major surgical and oncology meetings. She is a member of the American College of Surgeons, the American Society of Breast Surgeons, and the Society of Surgical Oncology, and remains deeply committed to advancing high-quality, patient-centered surgical cancer care.