Leukemia is a form of cancer, and thusly the kind of Doctor Who specializes in it is called an "Oncologist".
However, this specific disease may have some cross talk with another specialty called hematology - the specialty concerning blood and diseases in blood. A person within this kind of specialty is called a "hematologist".
A person who studies blood and its diseases is called a hematologist. They specialize in diagnosing and treating disorders related to the blood, such as anemia, leukemia, and bleeding disorders.
a person that studies gems is called a gemologist.
The Person Who studies about mamals , he is called mamalogist....
A person who studies animals is called a zoologist.
A person who studies physics is called a physicist, a person who studies chemistry is called a chemist, and a person who studies biology is called a biologist.
A person who studies the mind and behavior is called a psychologist.
A person who studies or writes history is called a historian.
A person who studies alligators is called a herpetologist.
A person who studies a lot is often called a "bookworm" or a "knowledge enthusiast."
A person who studies optometry is called an optometry student or an optometry student.
A person who studies culture is called an anthropologist.
A person who studies sound is called an acoustician.