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Richard Cedric Zellars, M.D.

Associate Professor of Radiation Oncology and Molecular Radiation Sciences



  • Associate Professor of Radiation Oncology and Molecular Radiation Sciences
  • Associate Professor of Oncology

Centers & Institutes



Breast Cancer, Cervical Cancer, Endometrial Cancer, Gynecologic Cancers, Radiation Oncology

Research Interests

Breast Cancer


Associate Professor of Radiation Oncology and Molecular Radiation Sciences
Associate Professor of Oncology
Assistant Director of Clinical Trial Accrual, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins

The complexity and prevalence of breast cancer drew Richard Zellars to this area of oncology. The bravery of breast cancer patients for whom, in Zellars’ experience, “much of the regular superficial stuff of life seems to fall to the wayside,” has made him ever more loyal to treating patients with the disease and conducting related research.

“My [research] goals are basically to improve the facility, safety and efficacy of radiation for breast cancer. We want it to be better, safer, and easier,” Dr. Zellars says. With these goals in mind, he describes some of his current research projects as “super exciting”.

The first study, which seeks both to shorten the course of treatment for breast cancer patients while making it more effective, involves treating only part of the breast (a method called partial breast irradiation) while simultaneously treating patients with chemotherapy. Previously, this combined method of treatment had been considered too toxic for patients. But delivering the radiation to a much more targeted location as opposed to the entire breast greatly reduces toxicity. And, Dr. Zellars points out, the combined treatment may improve patients’ outcomes.

In another cutting-edge study, he is examining the effects of combining radiation with PARP inhibitors—a relatively new class of drugs that have been shown in laboratory studies to prevent cancer cells from repairing broken DNA strands. Combining PARP inhibitors with radiation, theorizes Dr. Zellars, should kill more cancer cells than radiation alone.

“We’re offering this to women who have had pre-operative chemotherapy but whose cancer hasn’t gone away completely. Giving this combined treatment before surgery will hopefully minimize surgery required [after chemotherapy] and reduce the risk of the cancer returning,” he explains.

Dr. Zellars credits the support of his colleagues with his ability to conduct such innovative research. “It’s a phenomenal group of forward-thinking, open-minded breast physicians. Because of this team, we are re-thinking the breast cancer question. We’re willing to look at things we once held as fact and ask if they still hold true,” he says.

Dr. Richard C. Zellars is an Assistant Professor in the Department of Radiation Oncology and Molecular Radiation Sciences and in the Department of Oncology. He is a graduate of the Johns Hopkins School of Medicine and completed his residency in Radiation Oncology at the University of Michigan.

Previous appointments include Assistant Professorship in the Department of Radiation Medicine at Georgetown University Medical Center and Vice Chairmanship of the Department of Radiation Oncology at the University of Texas at San Antonio. Dr. Zellars primary clinical and research interests are in the treatment of Breast and Gynecologic cancers. He has received several grants to perform research in the treatment of breast cancer. Presently he is enrolling patients into a partial breast irradiation and concurrent chemotherapy trial of his design. This clinical trial decreases the duration of standard breast cancer therapy (chemotherapy followed by radiation after lumpectomy) from 5-6 months to less than 2 months. more

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    Additional Information

  • Education +
    • M.D., Johns Hopkins University School of Medicine (Maryland) (1991)
  • Research & Publications +

    Clinical Trial Keywords: breast cancer

    Selected Publications

    Ford, E.C.; Lavely, W.C.; Frassica, D.A.; Myers, L.T.; Asrari, F.; Wahl, R.L.; Zellars, R.C. Comparison of FDG-PET/CT and CT for delineation of lumpectomy cavity for partial breast irradiation. Int J Radiat Oncol Biol Phys. 2008 Jun 1;71(2):595-602.

    Balmanoukian, A.; Zhang, Z.; Jeter, S.; Slater, S.; Armstrong, D.K.; Emens, L.A.; Fetting, J.H.; Wolff, A.C.; Davidson, N.E.; Jacobs, L.; Lange, J.; Tsangaris, T.N.; Zellars, R.; Gabrielson, E.; Stearns, V. African American women who receive primary anthracycline- and taxane-based chemotherapy for triple-negative breast cancer suffer worse outcomes compared with white women. J Clin Oncol. 2009 Aug 1;27(22):e35-37; author reply e38-39.

    Ford, E.C.; Gaudette, R.; Myers, L.; Vanderver, B.; Engineer, L.; Zellars, R.; Song, D.Y.; Wong, J.; Deweese, T.L. Evaluation of safety in a radiation oncology setting using failure mode and effects analysis. Int J Radiat Oncol Biol Phys. 2009 Jul 1;74(3):852-858.

    Zellars, R.C. Deemphasize dogma: consider the local control-overall survival link. Oncology (Williston Park). 2009 Jul;23(8):679-680.

    Zellars, R.C.; Stearns, V.; Frassica, D.; Asrari, F.; Tsangaris, T.; Myers, L.; DiPasquale, S.; Lange, J.R.; Jacobs, L.K.; Emens, L.A.; Armstrong, D.K.; Fetting, J.H.; Garrett-Mayer, E.; Davidson, N.E.; Wolff, A.C. Feasibility trial of partial breast irradiation with concurrent dose-dense doxorubicin and cyclophosphamide in early-stage breast cancer. J Clin Oncol. 2009 Jun 10;27(17):2816-2822.
    Chumsri, S.; Jeter, S.; Jacobs, L.K.; Nassar, H.; Armstrong, D.K.; Emens, L.A.; Fetting, J.H.; Lange, J.R.; Riley, C.; Tsangaris, T.N.; Wolff, A.C.; Zellars, R.; Zhang, Z.; Stearns, V. Pathologic complete response to preoperative sequential doxorubicin/cyclophosphamide and single-agent taxane with or without trastuzumab in stage II/III HER2-positive breast cancer. Clin Breast Cancer. 2010 Feb;10(1):40-45.

    Ford, E.C., Lavely, W.C., Frassica, D.A., Myers, L.T., Asrari, F., Wahl, R.L., and Zellars, R.C. (2008). Comparison of FDG-PET/CT and CT for delineation of lumpectomy cavity for partial breast irradiation. Int J Radiat Oncol Biol Phys 71, 595-602.

    Zellars, R.C., Stearns, V., Frassica, D., Asrari, F., Tsangaris, T., Myers, L., DiPasquale, S., Lange, J., Jacobs, L., Emens, L.A., Armstrong, D., Fetting, J., Garrett-Mayer, E., Davidson, N.E. and Wolff, A.C. (2009). Feasibility Trial of Partial Breast Irradiation with Concurrent Dose-Dense Doxorubicin and Cyclophosphamide in Early Stage Breast Cancer. J Clin Onc 27, 2816-2822.

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