cancer center

Our Team

Your dedicated team includes board-certified medical, radiation and surgical oncologists, oncology-certified nurses, registered radiation therapists, a patient experience team, and experts in nutrition, integrative health and emotional and spiritual support.


Gregory B. Smith, MD

Medical Director, Medical Oncologist & Hematologist

Dr. Smith received his medical degree from UCLA School of Medicine in 1981 and continued with an Internship and Residency in Internal Medicine at UCLA San Fernando Valley, then completed his Fellowship in Hematology and Medical Oncology at Scripps Clinic and Research Foundation in La Jolla. He is Board-Certified by the American Board of Internal Medicine, American Board of Medical Oncology and the American Board of Hematology.

His distinguished career includes leadership of cancer research programs in Texas and California before he joined the St. Helena Hospital medical staff in 2001. Dr. Smith is known for his compassion and encouragement. “Never give up,” he states. “This is the conviction I have tried to impart to my patients and to my children. This is true for cancer treatment, sports, school or any endeavor.”


David Tate, MD

Radiation Oncologist

Dr. Tate attended University of Virginia, where he received his BA with high distinction in 1987 and medical degree in 1991. Following internship, he completed his residency training in Radiation Oncology at Stanford University in 1995. Dr. Tate joined the faculty as an Assistant Professor at Stanford from 1995 through 1999, where his clinical and research interests included treatment techniques such as stereotactic radiosurgery, brachytherapy and intensity modulated radiation therapy. He worked with Dr. Stephen Banks at Stanford for just over 3 years there.

Dr. Tate is Board-Certified in radiation oncology and has published articles in peer reviewed journals on treatment of disease ranging from lymphoma to prostate cancer. He is particularly interested in targeted radiation therapy techniques which minimize side effects of treatment. Dr. Tate also has extensive experience in treatment of patients with combination of chemotherapy and radiation therapy. When asked why he chose Martin-O’Neil Cancer Center he said, “I am delighted to be at a cancer center of excellence, providing advanced treatment techniques, as well as a holistic approach to patient care.”


Stephen J. M. Banks, MD

Radiation Oncologist

Dr. Banks received his medical degree from Stanford University in 1993, and then continued on at Stanford for his residency training in Radiation Oncology where he and Dr. David Tate worked together for over three years. In 1997, he joined Inova Alexandria Cancer Center, just outside Washington, D.C., as a Radiation Oncologist where he became the Director of Brachytherapy and Medical Director of this American College of Surgeons accredited community cancer center. While practicing in Virginia, Dr. Banks specialized in treatment of men with prostate cancer, and was a co-founding member of the Prostate Brachytherapy.Research Group. While practicing in the Washington, D.C. area, Washingtonian Magazine named him a Top Doctor for seven consecutive years.

He has personally performed more than 1200 prostate seed implants, and his results have been presented at national meetings and published in peer-reviewed journals. He currently works on a national level as a proctor training other physicians on how to perform prostate brachytherapy. In 2008, Dr. Banks and his family chose to return to California where he was recruited to develop a prostate cancer program by Redwood Regional Medical Group. Upon joining the Martin-O’Neil Cancer Center at St. Helena Hospital, he has been given the opportunity to realize a long time goal of developing a regional center of excellence for the management of prostate cancer. Dr. Banks is Board-Certified in Radiation Oncology.


Ethan D. Schram, MD

Oncologist & Hematologist

Dr. Schram received his medical degree from University of California, Davis in 2003. He completed his residency in Internal Medicine at Oregon Health & Science University and a Fellowship in Hematology/Oncology at Scripps Clinic and Research Foundation where he was Chief Fellow. Prior to joining the Martin-O’Neil Cancer Center, he was a Medical Oncologist at East Bay Medical Oncology-Hematology Associates.

He is Board-Certified in Oncology, Hematology and Internal Medicine and his recognitions include the Scripps Health Nell and Tom Waltz Award for Leadership in Medicine and the Northwestern University Lynn Sage Breast Cancer Achievement Award. Dr. Schram earned his undergraduate degree from Wesleyan and Columbia Universities.


Pedro Ramirez, MD

Surgical Oncologist & General Surgeon

Dr. Ramirez is a Board-Certified general surgeon and has a special interest in pancreatic cancer. Dr. Ramirez received his medical degree from Brown University and subsequently completed his residency in general surgery at the University of Alabama at Birmingham.

During residency, Dr. Ramirez spent time in a basic science laboratory studying gastrointestinal cancer through National Institutes of Health-sponsored funding. He completed an advanced gastrointestinal / hepato-pancreatico-biliary fellowship at the Johns Hopkins Hospital.


Tammy Tamayo, CCRC

Research and Clinical Trials Coordinator

Our Research and Clinical Trials Coordinator, in partnership with our Medical Director, directs our research programs. In this role, Tammy also connects patients to appropriate clinical trials and monitors the treatment protocols throughout the trial. Contact Tammy at 967.3698 for any questions regarding clinical trials or research.


Colleen Winters, LCSW, OSW-C

Clinical Navigator

Colleen Winters is the Clinical Navigator at the Martin-O’Neil Cancer Center at Adventist Health St. Helena. As a Licensed Clinical Social Worker and Board Certified in Oncology Clinical Social Work, she manages the Integrative Cancer Support Services and is the patient and family therapist at the Cancer Center.

She offers short-term Psycho Dynamic Therapy for a variety of issues such as anxiety and stress, how cancer affects intimacy, body image and how to navigate and cope with a life challenging illness. She introduces patients to advance care planning tools and palliative care. Colleen also connects patients to local and national resources as they consider their diagnosis and its impact on work and family during their cancer journey.

In her role managing the Integrative Cancer Support Services she has developed a full range of survivorship programs and services such as acupuncture, music therapy, yoga, guided imagery, support groups, mindfulness eating and meditation.

Colleen has over 20 years’ of management and direct service experience working in acute care and outpatient oncology. She has post graduate training in Behavioral Health Integration in Primary Care, Psycho-Dynamic Therapy and Advance Care Planning.

As a Clinical Navigator she is actively involved in community outreach and is constantly seeking creative ways to promote high quality programs and services for cancer survivors.