Dr. Marisa F. Siebel

I am a board certified medical oncologist treating all solid tumor malignancies,with special expertise in gastrointestinal malignancies, gynecological malignancies and head and neck cancer. I am the Director of GI Malignancies for the Eastern Region at Northwell Health Cancer Institute, and Chief of Hematology Oncology at Huntington Hospital. I collaborate with a multidisciplinary team of physicians, surgeons, radiation oncologists, pathologists, and radiologists to bring the best possible care to patients who wish to be treated close to home on Long Island. I am also an attending physician of the Don Monti Division of Medical Oncology and Hematology at North Shore University Hospital, Long Island Jewish Medical Center and Southside Hospital. Prior to joining Northwell Health, I was an attending physician at Memorial Sloan Kettering Cancer Center. I completed my Internal Medicine residency training at Maimonides Medical Center and my fellowship in Hematology and Oncology at the University of Vermont. In addition to my work as a clinician, I have a strong interest in clinical research. I immensely enjoy teaching and have mentored many young physicians during their training. I am proud to be part of a dedicated multidisciplinary team, providing state- of-the-art comprehensive care to all of our patients on Long Island.

Dr. Siebel is highly rated in 27 conditions, according to our data. Her clinical expertise encompasses Familial Colorectal Cancer, Colorectal Cancer, Merkel Cell Carcinoma, and Lynch Syndrome.

Dr. Siebel is board certified in American Board Of Internal Medicine/Medical Oncology. She is actively involved in clinical research, co-authoring 2 peer reviewed articles and participating in 1 clinical trial.