Trained as a radiation oncologist, his research focuses on the tumor microenvironment and Hedgehog pathway, which is involved in the epithelial-to-mesenchymal transition. This pathway appears to enhance tumor radioresistance, invasiveness, and metastasis and inhibiting this pathway could lead to improvement in cancer control in head and neck cancers in addition to several other cancers. Dr. Gan is a member of the American Society of Therapeutic Radiation Oncology, the American Board of Radiology and the American Medical Association. He has written multiple peer-reviewed research publications, book chapters, and abstracts, on various topics in cancer biology and radiation oncology.