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Our Physicians



Michael S. Gordon, M.D., a medical oncologist, is currently President and CEO of Pinnacle Oncology Hematology. Dr. Gordon is an Associate Professor of Clinical Medicine at the University of Arizona College of Medicine and is actively engaged in the education of medical students. Dr. Gordon’s principle interests have been in the development of new cancer therapies with a focus on targeted therapies as well as drugs that affect angiogenesis (tumor blood vessel supply). His disease focuses include kidney cancer, melanoma, prostate cancer, gastrointestinal stromal tumor (GIST) and ovarian cancer.

Dr. Gordon received his B.S. degree in Biomedical Sciences from the Sophie Davis School for Biomedical Education at the City College of New York and his M.D. degree from the State University of New York at Buffalo School of Medicine. Following his graduation from medical school Dr. Gordon performed his internship and residency in Internal Medicine at the University of Chicago Hospitals and Clinics from 1985 through 1988. After completing his fellowship in Hematology/Oncology at Memorial Sloan-Kettering Cancer Center in 1991 he accepted a position at the Indiana University School of Medicine as a faculty member in the Section of Hematology/Oncology. During nine years on the faculty at Indiana University, Dr. Gordon played integral roles in the development of the Indiana University Cancer Center’s Biologics and Developmental Therapeutics Program, the Leukemia Program, Clinical Research Office, and the Scientific Review Committee.

In 2000 Dr. Gordon re-located to Phoenix to become the Associate Dean for Research for the Phoenix Campus of the University of Arizona College of Medicine and subsequently founded the Arizona Cancer Center’s Drug Development Program in Scottsdale. Dr. Gordon led the Arizona Cancer Center’s activities in the greater Phoenix area until November 2005 when the Drug Development Program was converted to Pinnacle Oncology Hematology as a free-standing research practice.

Dr. Gordon’s hobbies include running and cycling.



David MendelsonDavid S. Mendelson, MD, has practiced medical oncology for 30 years in the greater Phoenix area. He received his medical degree and completed internal medicine residency at Ohio State University. After completing his fellowship training in medical oncology and hematology at Duke University, he joined the faculty there as a clinical instructor and research fellow in immuno-hematology. For twenty years he practiced medical oncology in Phoenix; during that interval he served as Chairman of the Department of Medicine and Executive Committee member at Thunderbird Samaritan (Banner) Medical Center.

In 2001, he joined the University of Arizona as an Assistant Professor of Clinical Medicine working with Dr. Gordon to create the Drug Development Program of the Arizona Cancer Center, Greater Phoenix Area. With the development of Pinnacle Oncology Hematology in 2005 Dr. Mendelson continued his interests in drug development. His cancer interests include prostate cancer, lung cancer and sarcomas.

Dr. Mendelson has served as a committee adviser for the American Society of Clinical Oncology to develop clinical care guidelines in the areas of prostate cancer and thrombotic (clotting) complications in cancer patients, as well as the society’s manpower evaluations. He has been a consultant to pharmaceutical industry drug development and for the National Cancer Institute’s drug assessment programs.



Giraldo KatoGiraldo Kato, M.D.  is a medical oncologist/hematologist and partner at Pinnacle Oncology  Hematology.  Dr. Kato received his undergraduate degree at Cornell University and his medical degree from the Universidad Central del Este in the Dominican Republic in 1985. He subsequently received a Masters of Public Health degree from the University of Miami and completed his residency in Internal Medicine in 1997 at East Carolina University School of Medicine where he served as Chief Resident.  His fellowship in both Hematology and Medical Oncology was completed at the Comprehensive Cancer Center of Wake Forest University in 1999.

Dr. Kato joined Pinnacle Oncology Hematology after serving as the Chief of Hematology/Oncology at Maricopa Medical Center and practicing in the Scottsdale area for several years. Dr. Kato has a special interest in breast cancer and coordinates the interdisciplinary breast cancer clinic at Pinnacle. His research interests include new breast cancer therapies as well as gastrointestinal and thoracic malignancies. He is an active member of ASCO, ASH, and ALMA.

Dr. Kato enjoys the outdoors and is a hiking enthusiast.



Giraldo KatoFrank Tsai, M.D., a medical oncologist and hematologist, received his Bachelor of Science Degree from the Sophie Davis School for Biomedical Education at the City College of New York and the Medical Doctorate from the State University of New York (SUNY) at Stony Brook School of Medicine. After completing his internship and residency in Internal Medicine at the SUNY Stony Brook School of Medicine, Dr. Tsai received his oncology and hematology fellowship training at Boston University School of Medicine.  Prior to moving to Arizona in 2013, he was an attending physician at the Memorial Sloan-Kettering Cancer Center in New York where he was involved in institutional guideline committees, clinical trials and international consultations.

Dr. Frank Tsai also believes that excellent patient care is a critical component of good medicine.  He has been nominated by cancer patients for The Arnold P. Gold Foundation Award that recognizes physicians for their integrity and compassionate care.

In his spare time, he enjoys photography and hiking with his family.