In addition to his academic medical education and training, Dr. Geffen has traveled extensively and has more than twenty-five years of experience exploring the great spiritual and healing traditions of the world, including Ayurveda, Tibetan Medicine, yoga, meditation, and other approaches to health and self-awareness.

Described as an "oncologist of the future," Dr. Geffen founded the Geffen Cancer Center and Research Institute (GCCRI), in Vero Beach, Florida, in 1994, which he directed until 2003. GCCRI was one of the first cancer centers in the United States explicitly designed to provide a working model of truly holistic, comprehensive cancer care for the 21st century. The Center was well-known for its unique, Seven Levels of Healing program which integrates state-of-the-art conventional cancer treatments with a wide array of complementary therapies designed to help patients and family members heal and transform at the deepest levels of the body, mind, heart, and spirit. Dr. Geffen practiced medical oncology and hematology for 11 years before closing the Center and leaving clinical practice in 2003 to work full-time for GVI. During his career as a practicing physician he provided guidance and care to thousands of patients and their loved ones.

Dr. Geffen is a summa cum laude graduate of Columbia University, and received his MD degree with honors from New York University School of Medicine. He completed residency training in Internal Medicine at the University of California at San Diego Medical Center, and fellowship training in Hematology and Oncology at University of California at San Francisco Medical Center. He is the recipient of research grants from the National Cancer Institute and the Research Coordinating Committee of the University of California. In 1995 he was elected a Fellow of the American College of Physicians.

Dr. Geffen's work is now focused on writing, speaking, and consulting with hospitals, medical centers, professional organizations, and communities in developing leading-edge integrative and multidimensional programs for medicine and life. He also leads seminars and retreats throughout the United States and abroad, and offers personal consulting services for individuals and their families.