Dr. Geoffrey Geiger

Geoffrey Geiger

Geoffrey Geiger
Radiation Oncologist

Languages spoken


Expert in

Proton therapy, brachytherapy, and stereotactic radiosurgery

Interested in

Music, photography, scuba diving 



Key West (Radiation oncology)
Key West (Radiation oncology)

3426 North Roosevelt Boulevard
Key West, Florida 33040

24.5716421, -81.7609958


3D Conformal Radiation Therapy
Service/Cancer/Radiation oncology
Service/Cancer/Radiation oncology/3D Conformal Radiation Therapy
CT scanning
Service/Cancer/Diagnostics imaging scans
Service/Cancer/Diagnostics imaging scans/CT scanning
Deep Inspiration Breath Hold (DIBH)
Service/Cancer/Radiation oncology
Service/Cancer/Radiation oncology/Deep inspiration breath hold
External Beam Radiation Therapy (EBRT)
Service/Cancer/Radiation oncology
Service/Cancer/Radiation oncology/External beam radiation therapy (EBRT)
Image Guided Radiation Therapy (IGRT)
Service/Cancer/Radiation oncology
Service/Cancer/Radiation oncology/Image guided radiation therapy (IGRT)
Intensity Modulated Radiation Therapy (IMRT)
Service/Cancer/Radiation oncology
Service/Cancer/Radiation oncology/Intensity modulated radiation therapy
Radiation therapy
Service/Cancer/Radiation oncology
Service/Cancer/Radiation oncology/Radiation therapy
Stereotactic Body Radiation Therapy (SBRT)
Service/Cancer/Radiation oncology
Service/Cancer/Radiation oncology/Stereotactic body radiation therapy (SBRT)

Dr. Geiger joined GenesisCare in 2018, bringing significant clinical and research expertise, having contributed to numerous abstracts and journal publications on radiation therapy and cancer treatments. He has presented this data at a number of national and international meetings as well as authored several textbook chapters. He is currently an Associate Professor of Radiation Oncology at the University of Central Florida College of Medicine. He brings special expertise in proton therapy, brachytherapy, as well as stereotactic radiosurgery, having worked extensively with both CyberKnife and Gamma Knife radiosurgery platforms. He also works extensively with the United States Department of Defense as a consultant on NBC (Nuclear, Biological, Chemical), as an integral member of the cabinet committee on the Counterterrorism Task Force in Washington DC.

His special interests include the treatment of head and neck cancers, skull base tumors, skin cancers, gynecological cancers, genitourinary and gastrointestinal malignancies. He completed his medical school training at the University of Pennsylvania School of Medicine and his internship and residency at the Hospital of the University of Pennsylvania in Philadelphia before joining the faculty there as an Assistant Professor of Radiation Oncology from 2012-2017, where he was the only faculty member simultaneously treating patients with both x-ray and proton radiotherapy, brachytherapy as well as CyberKnife and Gammaknife radiosurgery. When not treating cancer patients, Dr. Geiger is a musician, an avid photographer, both above and below water and Master Scuba Diver.



  • Bates College, B.S., Biological Chemistry, Lewiston, Maine
  • University of Pennsylvania School of Medicine, Doctor of Medicine, Philadelphia, Pennsylvania


  • Hospital of the University of Pennsylvania, Internal Medicine, Philadelphia, Pennsylvania


  • Hospital of the University of Pennsylvania, Radiation Oncology, Philadelphia, Pennsylvania

Expertise and interests

  • Expertise in Head & Neck, Skin, Gynecological, Gastrointestinal, and Genitourinary Malignancies as well as extensive experience with Proton therapy, brachytherapy, and radiosurgery (CyberKnife & Gamma Knife) in addition to standard x-ray radiotherapy (3D

Professional association

  • American College of Radiation Oncology (ACRO) 2017 - Present
  • American Head & Neck Society (AHNS) 2015 - Present
  • International Association for the Study of Lung Cancer (IASLC) 2011 - Present
  • American Radium Society (ARS) 2009 - Present
  • Radiological Society of North America (RSNA) 2009 - Present 
  • Particle Therapy Co-Operative Group (PTCOG) 2008 - Present
  • American College of Radiology (ACR) 2008 - Present
  • American Society of Clinical Oncology (ASCO) 2008 - Present
  • American Brachytherapy Society (ABS) 2008 - Present
  • American Society of Radiation Oncology (ASTRO) 2005 - Present
  • American Medical Association (AMA) 2002 - Present
  • Head and Neck Cancer, Cancergrace.org 2014 - Present
  • RNSA-ACR Website Committee on Head and Neck Cancers 2013 - Present 



  • Charles A. Dana Scholar, Summa Cum Laude, Phi Beta Kappa, Gamma of Maine, Sigma Xi Honor society, NIH Cancer Research Fellowship recipient, Ruth L. Kirschstein NRSA Award National Research Service Grant, and recipient of the Rose Meadow Levinson Memorial


  • Geoffrey A. Geiger, Andrew P. Beothy and Gary D. Kao: Rapid bioluminescent detection of caspase activation induced after radiation and radioprotection in Zebrafish embryos. Pro Amer Associ Cancer Res 66(47), Apr 2006.
  • Geiger Geoffrey A, Beothy Andrew P, Tucker Jennifer A, Mullins Mary C, Kao Gary D: Zebra fish as a "biosensor"? Effects of ionizing radiation and amifostine on embryonic viability and  development. Cancer Research 66(16): 8172-81, Aug 2006.
  • Lally BE, Geiger GA, Kridel S, Wheeler K, et al.: Identification of a novel, potent small molecular radiation sensitizer for glioblastoma cells via an unbiased screen of a chemical library. Cancer Research 67(18): 8791-8799, Sept 2006.
  • Lally BE, Geiger GA, Kridel S, Arcury-Quandt AE, Robbins ME, Kock ND, Wheeler K, Peddi P, Georgakilas A, Kao GD, Koumenis C: Identification and biological evaluation of a novel and potent small molecule radiation sensitizer via an unbiased screen of a chemical library. Cancer Research 67(18): 8791-9, Sep 2007.
  • Geiger GA, Fu W, Kao GD: Temozolomide-mediated radiosensitization of human glioma cells in a zebrafish embryonic system. Cancer Research 68(9): 3396-3404, May 2008. 
  • Weiss J, Geiger GA, Lin A, Langer CJ: A hole in the heart. Journal of Thoracic Oncology 5(1): 144-145, Jan 2010. 
  • Plastaras JP, Geiger G, Perini R, Glatstein E: The Use of PET in Radiation Therapy for Lymphoma: PET Clin. 2012 Jan;7(1):67-72 
  • Geiger GA, Kim MB, Xanthopoulos EP, Pryma DA, Grover S, Plastaras JP, Langer CJ, Simone CB 2nd,  Rengan R.: Stage migration in planning PET/CT scans in patients due to receive radiotherapy for non-small-cell lung cancer. Clinical Lung Cancer 15(1): 79-85, Jan 2014.
  • Ojerholm E, Lee JY, Thawani JP, Miller D, O'Rourke DM, Dorsey JF, Geiger GA, Nagda S, Kolker JD, Lustig RA, Alonso-Basanta M: Stereotactic radiosurgery to the resection bed for intracranial metastases and risk of leptomeningeal carcinomatosis. Journal of Neurosurgery 121 Suppl 2: 75-83, Dec 2014.
  • Vogel Jennifer, Ojerholm Eric, Hollander Andrew, Briola Cynthia, Mooij Rob, Bieda Michael, Kolker James, Nagda Suneel, Geiger Geoffrey, Dorsey Jay, Lustig Robert, O'Rourke Donald M, Brem Steven, Lee John, Alonso-Basanta Michelle: Intracranial control after Cyberknife radiosurgery to the resection bed for large brain metastases. Radiation Oncology (London, England) 10: 221, Oct 2015.
  • Chowdhury Imran H, Ojerholm Eric, McMillan Matthew T, Miller Denise, Kolker James D, Kurtz Goldie, Dorsey Jay F, Nagda Suneel N, Geiger Geoffrey A, Brem Steven, O'Rourke Donald M, Zager Eric L, Gangadhar Tara, Schuchter Lynn, Lee John Y K, Alonso-Basanta Michelle: Novel risk scores for survival and intracranial failure in patients treated with radiosurgery alone to melanoma brain metastases. Radiation Oncology (London, England) 10(1): 248, Dec 2015.
  • Piazza Matthew, Ramayya Ashwin, Geiger Geoffrey, Alonso-Basanta Michelle, Nasrallah MacLean P, Welch William, Ozturk Ali: Intramedullary recurrence of a thoracic meningioma - Presentation of an unusual case and review of the literature. World Neurosurgery Feb 2016.
  • Ojerholm Eric, Lukens J Nicholas, Ahn Peter H, Geiger Geoffrey, Swisher-McClure Samuel, Newman Jason, Chalian Ara, Weinstein Gregory, O'Malley Bert W, Cohen Roger, Lin Alexander: Benefits of omitting primary site radiation therapy after transoral robotic surgery: Only time will tell. Practical Radiation Oncology 7(3): e157-e158, May - June 2017.
  • Ruangkanchanasetr R, John YK Lee, Suneel N Nagda, Geoffrey A Geiger, James D Kolker, Douglas C Bigelow, Michael J Ruckenstein, MacLean Nasrallah, Michelle Alonso-Basanta: Toxicity of Gamma Knife radiosurgery may be greater in patients with lower cranial nerve schwannomas. J Neurol Surg B Skull Base  2018 Dec;79(6):580-585 May 10.  
  • Samuel Swisher-McClure, John N Lukens, Charu Aggarwal, Peter Ahn, Devraj Basu, Joshua M Bauml, Robert Brody, Ara Chalian, Roger B Cohen, Alireza Fotouhi-Ghiam, Geoffrey Geiger, Jared Gershowitz, Virginia Livols, Nandita Mitra, Kathleen Montone, Jason Newman, Eric Ojerholm, Bert O'Malley Jr, Karthik Rajasekaran, Erik Tan, Gregory Weinstein, Alexander Lin: A Phase 2 Trial of Alternative Volumes of oropharyngeal irradiation for de-intensification (AVOID): omission of the resected primary tumor bed after transoral robotic surgery (TORS) for human papilloma virus-related squamous cell carcinoma of the oropharynx Int J Radiat Oncol Biol Phys 2020 Mar 15;106(4):725-732.
  • Jean-Pierre Bissonnette, Alexander Sun, Inga S. Grills, Muayad F. Almahariq, Geoffrey Geiger, Wouter Vogel, Jan-Jakob Sonke, Sarah Everitt, Michael Mac Manus: Non-small cell lung cancer stage migration as a function of wait times from diagnostic imaging: A pooled analysis from five international centres Lung Cancer 2021 Volume 155, p136-143, May 1, 2021.