LeoGlossary: Cancer

Cancer is a broad term for a group of diseases in which cells grow uncontrollably and spread to other parts of the body. There are over 200 different types of cancer, and each type can be further classified into subtypes based on the location of the cancer, the type of cells involved, and the stage of the cancer.

How Cancer Starts

Cancer starts when normal cells undergo changes that allow them to grow and divide uncontrollably. These changes can be caused by a variety of factors, including:

Genetic mutations: Genetic mutations are changes in the DNA that controls the growth and division of cells.
Exposure to carcinogens: Carcinogens are substances that can cause cancer. These include tobacco smoke, radiation, and certain chemicals.
Viruses: Some viruses can cause cancer, such as the human papillomavirus (HPV) and the hepatitis B virus (HBV).
Lifestyle factors: Lifestyle factors such as smoking, unhealthy diet, and lack of exercise can increase the riskof developing certain types of cancer.

How Cancer Grows and Spreads

Once cancer cells start to grow uncontrollably, they can invade and destroy nearby tissues. They can also spread to other parts of the body through the bloodstream or the lymphatic system. This process is called metastasis.

Symptoms of Cancer

The symptoms of cancer can vary depending on the type of cancer and where it is located in the body. Some common symptoms of cancer include:

Unexplained weight loss
Fatigue
Fever
Pain
Changes in bowel or bladder habits
Unusual bleeding or discharge
A sore that does not heal
A lump or thickening in the breast or elsewhere

Diagnosis and Treatment of Cancer

There are a number of tests that can be used to diagnose cancer, including:

Physical examination
Biopsy
Imaging tests such as X-rays, CT scans, and MRIs
Blood tests

Once cancer has been diagnosed, there are a number of different treatments that may be used, depending on the type of cancer, the stage of the cancer, and the patient's overall health. Some common cancer treatments include:

Surgery: Surgery is the removal of cancer cells from the body.
Radiation therapy: Radiation therapy uses high-energy rays to kill cancer cells.
Chemotherapy: Chemotherapy is the use of drugs to kill cancer cells.
Targeted therapy: Targeted therapy uses drugs that target specific molecules on cancer cells.
Immunotherapy: Immunotherapy uses the body's own immune system to fight cancer.

##Prevention of Cancer

There are a number of things that people can do to reduce their risk of developing cancer, including:

Not smoking
Eating a healthy diet
Maintaining a healthy weight
Getting regular exercise
Limiting exposure to the sun
Getting regular cancer screenings

Types (Classifications) of Cancer

There are many different types of cancer, and they can be classified in a variety of ways according to location, tissue type, and behavior. The most common types of cancer are classified according to the tissues or organs that they first arise from.

Here are some examples of the different types of cancer:

Carcinoma: Carcinomas are the most common type of cancer. They arise from epithelial cells, which are the cells that line the surfaces of the body's organs and glands. Examples of carcinomas include lung cancer, breast cancer, and colon cancer.

Sarcoma: Sarcomas are cancers that arise from connective tissues, such as bone, cartilage, muscle, and fat. Examples of sarcomas include osteosarcoma (bone cancer), rhabdomyosarcoma (muscle cancer), and Kaposi's sarcoma (a cancer that affects the skin and blood vessels).

Leukemia: Leukemia is a cancer of the blood cells. It is characterized by the uncontrolled growth of white blood cells, which normally help the body fight infection. There are four main types of leukemia: acute myeloid leukemia (AML), chronic myeloid leukemia (CML), acute lymphocytic leukemia (ALL), and chronic lymphocytic leukemia (CLL).

Lymphoma: Lymphoma is a cancer of the lymphatic system, which is a network of vessels and nodes that carry lymph fluid throughout the body. Lymph fluid contains lymphocytes, which are a type of white blood cell. There are two main types of lymphoma: Hodgkin lymphoma and non-Hodgkin lymphoma.

Brain and central nervous system (CNS) cancers: Brain and CNS cancers are cancers that arise from the tissues of the brain and spinal cord. Examples of brain and CNS cancers include glioblastoma (the most common type of brain cancer), meningioma, and schwannoma.

In addition to these broad categories, there are many subtypes of each type of cancer. These subtypes are based on the specific type of cell involved, the location of the cancer, and the stage of the cancer. The stage of a cancer describes how far it has spread from its original location. Cancers are typically staged from I to IV, with stage I being the least advanced and stage IV being the most advanced.

The treatment of cancer depends on the type of cancer, the stage of the cancer, and the patient's overall health. Some common cancer treatments include surgery, radiation therapy, chemotherapy, targeted therapy, and immunotherapy.

Cancer is a complex and challenging disease, but researchers are constantly learning more about it and developing new treatments. With early diagnosis and treatment, many people with cancer can live long and healthy lives.

Here are some additional resources that you may find helpful: