Rena D. Callahan, MD
Accepting new patients

Rena D. Callahan, MD

  • Breast Medical Oncology
Average rating: 5.0
| 416 ratings
Santa Clarita Cancer Care | 27235 Tourney Road, Suite 2400, Valencia, CA 91355


Dr. Rena Callahan is a hematologist oncologist who practices in Santa Monica and Santa Clarita. As an associate clinical professor of medicine at the David Geffen school of medicine, she is active in the breast cancer research and treatment program. She is board certified in hematology and medical oncology, and sees a wide variety of malignancies and blood disorders.  

Dr. Callahan is dedicated to providing patient-centered care, and including her patients in clinical decision making so that their individual goals are met. 

Dr. Callahan received her medical degree from the University of Pennsylvania School of Medicine, where she graduated Alpha Omega Alpha, with high honors. She completed her internal medicine and hematology/oncology training at UCLA. She received her Bachelor of Science degree in biology from Yale University.

Dr. Callahan has spoken about the evolving treatment of breast cancer at both local and national meetings.




Medical Board Certifications

Hematology, American Board of Internal Medicine, 2011
Medical Oncology, American Board of Internal Medicine, 2011


Hematology & Medical Oncology, UCLA School of Medicine, 2011


Internal Medicine, UCLA School of Medicine, 2007


Internal Medicine, UCLA School of Medicine, 2005


MD, University of Pennsylvania School of Medicine, 2004

Hospital Affiliations

Ronald Reagan UCLA Medical Center

UCLA Santa Monica Medical Center

Medical Services



  • Breast Cancer
  • Treating side effects of cancer therapy


  1. Evaluation of an NP-based model of palliative care delivery within an oncology clinic. Sarah F. DAmbruoso, Neil Wenger, Anne Coscarelli, Sara A. Hurvitz, Christopher Pietras, Meghan Nechrebecki, Jennie Kung, Rena Desai Callahan, Jonathan Wade Goldman, Parvin F. Peddi, Drakaki Alexandra, Samuel A. Skootsky, and Anne Margaret Walling Journal of Clinical Oncology20173531_suppl163-163
  2. 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,
  3. Jennifer S. Woo, Neda A. Moatamed, Peggy S. Sullivan, David Y. Lu, Rena Callahan et al. (2015) Comparison of Phosphohistone H3 Immunohistochemical Staining, Ki-67, and H&E Mitotic Count in Invasive Breast Carcinoma. Journal Of Breast Cancer Survival - 1(1):1-11.
  4. Ponec, R., Peddi, P., Callahan, R. "Parp inhibitors in Breast Cancer: Latest Evidence." Current Breast Cancer Reports. Vol 9, 2017.
  5. Rena Callahan. Ado-Trastuzumab Emtansine in Metastatic HER2-Positive Breast Cancer. J Adv Pract Oncol. 2014 Mar-Apr; 5(2): 134–139.
  6. 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: 978-1-4511-8627-7.
  7. 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.
  8. R.Callahan, R. Patel, D.Chan, M.Allison, B. Dicarlo, L. Bosserman, A. Kennedy, L.M. Zehngebot, J. Miller, A.E. Giuliano, B. Spivack, L.S. Lin, D.J. Slamon, S.A. Hurvitz. Phase II Trial of Presurgical Treatment with Trastuzumab (H) or Lapatinib (Ty) or the Combination of Trastuzumab and Lapatinib (H+Ty), Followed by Six Cycles of Docetaxel (T) and Carboplatin (C) with Trastuzumab (TCH) or Lapatinib (TCTy) or the combination of Trastuzumab and Lapatinib (TCHTy) in Patients with HER2+ Breast Cancer. 2010 San Antonio Breast Cancer Symposium, December 2010.
  9. Richard P. Tonino, Pierre J. Meunier, Ronald Emkey, Jose A. Rodriguez-Portales, Charles-Joel Menkes, Richard D. Wasnich, Henry G. Bone, Arthur C. Santora, Mei Wu, Rena Desai, and Philip D. Ross. “Skeletal benefits of Alendronate: 7-Year Treatment of Postmenopausal Osteoporotic Women.” J. Clin. Endocrinol. Metab. 2000. 85: 3109-3115.
  10. Rena Desai Callahan, K. Rajender Reddy. “Liver Disease in Pregnancy.” The Clinician’s Guide to Liver Disease. Ed. Reddy KR and Faust T. Philadelphia: Slack, 2006: 211-230.


  • Aetna
  • Anthem Blue Cross
  • Blue Shield of California
  • Centivo
  • Cigna
  • First Health
  • Health Net of California
  • Interplan (part of HealthSmart)
  • L.A. Care
  • MultiPlan
  • UFCM Health System
  • Prime Health Services
  • Private Healthcare Systems (PHCS)
  • 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.


  • Super Doctors® Southern California, 2021-2024
  • Castle Connolly Top Doctors, 2018-2024
  • 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