Medical Oncology is the discipline which diagnoses and treats cancer. The latter is a disease caused by the uncontrolled growth of certain damaged cells. It therefore covers a large variety of diseases, depending on the zone in which the malignant tumour which causes the cancer originates (lung cancer, breast cancer, colon cancer, skin cancer or prostate cancer are a few examples). Oncology consists of diagnosing the origin of the cancer as soon as possible and fighting against its development using various types of treatments, which will depend on the progression of the cancer in question and the characteristics of the patient. A medical oncologist is a professional dedicated specifically to the study and prevention of patients who are susceptible to suffering cancer, as well as the treatment of those who already have it. Therefore the relationship between a patient and their medical oncologist is maintained over a fairly prolonged period of time.