Dr. Rena Callahan is a specialist in medical oncology in Santa Monica, California and she is affiliated with many local hospitals, like Henry Mayo Newhall Memorial Hospital and UCLA Medical Center. She graduated from Perelman School of Medicine at the University of Pennsylvania where she got her medical degree. She did her residency program in internal medicine at UCLA Medical Center. She also did a fellowship in hematology/oncology at the same institution. The doctor is board certified in internal medicine, hematology, and medical oncology and she has a practical experience of more than 20 years.