Final answer:
A specialist who studies or treats tumors is known as an oncologist. Oncologists work closely with pathologists for diagnosis and use various treatments including radiation therapy to control or cure cancer.
Step-by-step explanation:
A specialist who studies or treats tumors is called an oncologist. Oncologists are medical doctors who specialize in diagnosing and treating cancer, which may include using treatments like surgery, chemotherapy, radiation therapy, and immunotherapy.
Within oncology, there are physicians known as radiation oncologists who specifically use radiation therapy to control and shrink malignant tumors. It's also important to note the role of pathologists, who are doctors that diagnose diseases by examining body tissues, often working with oncologists to provide a definitive diagnosis of cancer through techniques such as biopsies.