There are three different types of oncologists (medical, surgical and radiation) who all work together to ensure that the cancer plaguing their patients is well and truly beaten. A surgeon for instance, will cut out the tumor while medical and radiation oncologists will come in later with chemo and radiotherapy.
While a general practitioner can diagnose and treat a lot of common ailments, they typically do not have the training needed to treat more complex cases. However, they do play a very important role as they can quarterback your treatment by referring you to the appropriate specialist.
Many doctors choose to specialize but there are those who opt to further their expertise by sub-specializing. An orthopedist for instance, may choose to train in pediatric orthopedics and focus their practice on that discipline.
If your laryngitis doesn't go away after a few days of not talking, see your doctor. In some cases, it may be caused by nodules or polyps on the vocal chords. Your doctor will identify the problem and recommended appropriate treatment.
A doctor who chooses to focus on enhancing aesthetics is known as a cosmetic surgeon. To become one, a physician would need to go through many years of training in reconstructive surgery as well as pass tests that are given by the medical board that controls the practice.
A surgical oncologist removes cancer from the bodies of their patients. Their methods are particularly effective for solid cancers, although patients who've undergone cancer surgery may also receive multi-modal care (i.e. radiotherapy and chemotherapy) to ensure success.