Oncology



How cancer begins:

Cells are the basic units that make up the human body. Cells grow and divide to make new cells as the body needs them. Usually, when cells get too old or damaged, they die. Then new cells take their place. Cancer begins when genetic changes impair this orderly process. Cells start to grow uncontrollably. These cells may form a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread. Some types of cancer do not form a tumor. These include leukemia, most types of lymphoma, and myeloma.

Types of cancer

Doctors divide cancer into types based on where it began. Four main types of cancer are:

  1. Carcinoma
    It begins in the skin or the tissue that covers the surface of internal organs and glands. Carcinomas usually form solid tumors. They are the most common type of cancer. Examples of carcinomas include prostate cancer, breast cancer, lung cancer, and colorectal cancer.
  2. Sarcoma
    A sarcoma begins in the tissues that support and connect the body. A sarcoma can develop in fat, muscles, nerves, tendons, joints, blood or lymph vessels, cartilage, or bone.
  3. Leukemia
    Leukemia is a cancer of the blood. Leukemia begins when healthy blood cells change and grow uncontrollably. The four main types of leukemia are acute lymphocytic leukemia, chronic lymphocytic leukemia, acute myeloid leukemia, and chronic myeloid leukemia.
  4. Lymphoma.
    Lymphoma is a cancer that begins in the lymphatic system. The lymphatic system is a network of vessels and glands that help fight infection. There are two main types of lymphomas: Hodgkin lymphoma and non-Hodgkin lymphoma.

Types of Oncologists

The field of oncology has three major areas: medical, surgical, and radiation.

  • A medical oncologist treats cancer using chemotherapy or other medications, such as targeted therapy.
  • A surgical oncologist removes the tumor and nearby tissue during an operation. He/she also performs certain types of biopsies.
  • A radiation oncologist treats cancer using radiation therapy.


Other types of oncologists include the following:

  • A gynecologic oncologist treats gynecologic cancers, such as uterine cancer and cervical cancer.
  • A pediatric oncologist treats cancer in children. Some types of cancer occur most often in children and teenagers, such as certain brain tumors, leukemia, osteosarcoma, and Ewing’s sarcoma. But they sometimes occur in adults. In these cases, an adult may decide to work with a pediatric oncologist.
  • A hematologist-oncologist diagnoses and treats blood cancers, such as leukemia, lymphoma, and myeloma.
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