Rena D. Callahan, MD
- Breast Medical Oncology
About
About Dr. Rena Callahan
Dr. Rena Callahan is a board-certified hematologist and medical oncologist who specializes exclusively in the diagnosis and treatment of breast cancer. Practicing in Santa Monica and Santa Clarita, she integrates the latest advances in precision medicine, molecular diagnostics, and targeted therapies to deliver highly personalized care. As an Associate Clinical Professor of Medicine at the David Geffen School of Medicine at UCLA, Dr. Callahan is deeply involved in breast cancer research and remains at the forefront of emerging treatment strategies.
Dr. Callahan is committed to using state-of-the-art tools to guide clinical decisions, including genomic profiling, advanced imaging, and biomarker-driven approaches. She believes in a collaborative, patient-centered model of care, where each treatment plan is tailored to the individual’s biology, goals, and lifestyle. Her open-minded and empathetic approach fosters trust and empowers patients to actively participate in their care journey.
A graduate of the University of Pennsylvania School of Medicine, Dr. Callahan earned high honors and was inducted into the Alpha Omega Alpha Honor Medical Society. She completed her residency in internal medicine and fellowship in hematology/oncology at UCLA, and holds a Bachelor of Science in Biology from Yale University. A frequent speaker at both local and national conferences, Dr. Callahan is passionate about advancing breast cancer care and is dedicated to improving outcomes through innovation, education, and compassionate expertise.
Languages
Education
Medical Board Certifications
Fellowship
Residency
Internship
Degree
Recognitions
- Super doctors, Southern California, 2025
- Super Doctors® Southern California, 2021-2025
- Castle Connolly Top Doctors, 2018-2025
- Super Doctors Southern California Rising Stars, 2016-2018
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Related Clinical Trials
Locations
Hospital Affiliations
Ronald Reagan UCLA Medical Center
UCLA Santa Monica Medical Center
Medical Services
Areas of Focus
Research
Interests
- Breast Cancer
- Treating side effects of cancer therapy
Publications
- Jennifer S Woo, Neda A Moatamed, Peggy Sullivan, David Y Lu, Rena D. Callahan, Sophia Apple. “Comparison of PHH3, Ki-67 and H&E Mitotic Count in Invasive Breast Carcinoma.” J Br. Cancer Survival. 15 Oct 2015; Vol 1, Issue 1.
- R J Hartmaier S E Trabucco N Priedigkeit J H Chung C A Parachoniak P Vanden Borre S Morley M Rosenzweig L M Gay M E Goldberg , J Suh S M Ali J Ross B Leyland-Jones B Young C Williams B Park M Tsai B Haley J Peguero R D Callahan I Sachelarie J Cho J M Atkinson A Bahreini A M Nagle S L Puhalla R J Watters Z Erdogan-Yildirim L Cao S Oesterreich A Mathew P C Lucas N E Davidson A M Brufsky G M Frampton P J Stephens J Chmielecki A V Lee . “Recurrent Hyperactive ESR1 Fusion Proteins in Endocrine Therapy-Resistant Breast Cancer. Annals of Oncology, Volume 29, Issue 4, 1 April 2018, Pages 872–880.
- Sara Hurvitz, Dr.; Rashi Singh; Brad Adams, PhD; Julie Taguchi, MD; David S Chan, MD; Robert Dichmann, MD; Aurelio B Castrellon, MD; Eddie Hu, MD; Jonathan Berkowitz, MD; Aruna Mani, MD; Brian DiCarlo, MD; Rena D Callahan, MD; Ira Smalberg, MD; Xiaoyan Wang, PhD; Ivana Melgar, MS; Diego A Martinez, PhD; Evie Hobbs, MD; Dennis J Slamon, MD, PhD, “Phase Ib/II single-arm trial evaluating the combination of everolimus, lapatinib and capecitabine for the treatment of HER2-positive breast cancer with brain metastases (TRIO-US B-09).” Therapeutic Advances In Medical Oncology. 9 Nov 2018 doi: 10.1177/1758835918807339
- Rena D. Callahan, Patricia A. Ganz. “Side Effects of Systemic Therapy: Neurocognitive, Cardiac, and Secondary Malignancies.” Diseases of the Breast, 5th edition, Ed. Jay R. Harris, MD, Marc E. Lippman, MD, Monica Morrow, MD, and C. Kent Osborne, MD. Lippincott Williams and Wilkins, May 2014, 1224. ISBN: 978-14511-8627-7.
- Alkassis, S. Callahan, R., Bardia, A. Cytotoxic Therapy in Metastatic Hormone-Receptor Breast Cancer: Antibody-Drug Conjugates and Chemotherapy in Focus. ASCO Educational Book 2025
- RD Callahan, SA Hurvitz. HER2-Positive Breast Cancer: Current Management of Early, Advanced, and Recurrent Disease. Current Opinions in Obstetrics and Gynecology, 2011 Feb. 23 (1): 37-43.
- Rena Callahan. Ado-Trastuzumab Emtansine in Metastatic HER2Positive Breast Cancer. J Adv Pract Oncol. 2014 Mar-Apr; 5(2): 134– 139.
- Ponec, R., Peddi, P., Callahan, R. “Parp inhibitors in Breast Cancer: Latest Evidence.” Current Breast Cancer Reports. Vol 9, 2017.
- Dickinson BP, Nikkie Vu-Huynh BS, Monica B Vu BS, Senofsky G, Judy Pham RN, Ayushi Patel BS, Dennis R Holmes, Kelsey Shay, Rena Callahan and Peter Ashjian Internal mammary node positivity and autologous mastectomy reconstruction: Implications for breast cancer treatment and aesthetic outcome. Int J Radiol Radiat Oncol 7(1): 014-021. 23 March 2021. DOI: 10.17352/ijrro.00004
In the News
Articles & Features
Other Videos
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Patient Profile 2: How Should T-DM1 Be Sequenced in HER2+ mBC? - OncLive.com
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Patient Profile 3: 43-Year-Old Woman With Metastatic Breast Cancer Progressing Through Multiple Lines of Therapy - OncLive.com
Medical Education
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Breast Cancer 2017: Not Your Mother’s Treatment Options - Simms/Mann – UCLA Center
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Breast Cancer Treatment: Past, Present, and Future -Simms/Mann – UCLA Center Vimeo
Podcasts
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AJMC Panel Discussion: Oral SERDs in Oncology
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PeerDirect Compendium Program: Understanding HER2-Low Breast Cancer
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Noetic Insight: SABCS 2024 Updates
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Breast Cancer Connect / COR2ED: Molecular Testing in Metastatic Breast Cancer
Note: News links may expire without notice.
Insurance
- Aetna
- Anthem Blue Cross
- Blue Shield of California
- Centivo
- Cigna
- First Health
- Health Net of California
- Interplan (part of HealthSmart)
- Medicare Advantage
- MultiPlan
- UFCM Health System
- Prime Health Services
- Private Healthcare Systems (PHCS)
- TRICARE
- UnitedHealthcare
The list of health care plans above may not be comprehensive and could change.
Please contact your benefits coordinator or health insurance company directly to verify coverage.
Visit our health insurance information page for more details.
Recognitions
- Super Doctors® Southern California, 2021-2025
- Castle Connolly Top Doctors, 2018-2025
- Super Doctors Southern California Rising Stars, 2016-2018
- Henry Mayo Newhall Hospital Foundation, "Healthcare Hero", 2015-2018
- Commendation for Excellence in Medical Student Teaching, UCLA, 2005-2007
- Russell J. Stumacher Memorial Award, for academic and artistic excellence, University of Pennsylvania School of Medicine, 2004
- Glasgow Rubin Award, for academic excellence, University of Pennsylvania School of Medicine, 2004
- Alpha Omega Alpha medical honor society, inducted 2003
- Yale Class of 1956, Summer Fellowship for Study Abroad, 1996