When we say types of cancer, we may either mean the various types of cancers according to the site of origin such as breast cancer, or it can also mean the different kinds of cancers according to their pathological classification.
Cancer is cancer but different tissues of the body are associated with different kinds of cancer, each of which has its own pathological characteristics.
If we talk of type of cancer according to their site of origin, there would be more than 100 types of cancers to discuss, such as breast cancer, lung cancer, colorectal cancer, prostate cancer, etc.
It is not possible to describe them each in one article and need a separate article for each. Here, we will talk about the pathological classification of cancer and a short description of each type.
The type differs from the stage of cancer, which tells you what is the status of the cancer and how much it has grown
Types of Cancer
Doctors type cancer depending on the tissue cells of its origin. Accordingly, we have
- Carcinoma originating in the epithelial cells
- Leukemia originating in the bone marrow
- Sarcoma originating in the connective tissue
- Cancer originating in the central nervous system
- Lymphoma starts to develop in the lymph nodes of the lymphatic system
- Myeloma is cancer of the plasma cells of the bone marrow
Carcinomas are the most common type of cancer and make up about 80 to 90% of cancers diagnosed.
There are four types of body tissues: Epithelial, connective, muscle, and nervous tissue. Carcinomas originate in the epithelial cells of the epithelial tissue.
Epithelial tissues are present throughout the body. They cover all body surfaces; they form the lining of body cavities and hollow organs and are the major tissue found in glands. The Epidermis, which is the outer layer of the skin, is one example.
The epithelial tissue is present in:
- the membranes that line the body cavities
- on the surface of the structures in the body and
- in the glands of the body
Epithelial cells exist in three different shapes:
Carcinoma is the growth of the epithelial tissues that develop where epithelial tissue is present and is named according to the type of epithelial cells that turns malignant.
- Squamous cell carcinoma, called epidermoid carcinoma, is a malignancy of the squamous cells of the epithelium that are situated just under the outer surface of the skin. These cells also line many other organs, including the stomach, intestines, lungs, bladder, and kidneys. This cancer is seen in various organs such as the skin, mouth, lips, esophagus, prostate, urinary bladder, ovaries, cervix, vagina, and lungs.
- Basal cell carcinoma occurs in the basal or the lower cells of the epidermis. It is a common skin cancer occurring on parts of the skin that are exposed to sunlight.
- Adenocarcinoma is a cancer that develops in epithelial cells that produce secretions or mucus. This type of epithelial cell is sometimes referred to as glandular tissue. Examples include cancers of the breast, colon, and prostate.
- Transitional cell carcinoma is cancer that develops in a type of epithelial tissue called transitional epithelium, or urothelium. This tissue lines the bladder, ureters, the pelvis of the kidney, and a few other organs.
Leukemias are uncommon. They make up only 3% of all cancer cases. In children, however, they are the most common type of cancer.
Leukemia is a blood cancer where the origin of malignancy is in the bone marrow. Bone marrow is a soft tissue, which is found inside the bones. The bone marrow, in large bones, serves the function of producing red blood cells, platelets, and white blood cells.
Leukemia is characterized by a very abnormal increase in white blood cells in the blood. The normal WBC count is 4000 to 10,000 per microliter of blood.
In leukemia, this WBC count is seen in lacs, while the platelet count drops. These WBCs seen in leukemia are immature and dysfunctional thereby adversely affecting the immune system.
Leukemia may be acute or chronic depending on a rapid increase or slow sustained increase in the WBCs.
Just as carcinoma is cancer of the epithelial tissue, sarcoma is the cancer of the connective tissue. Sarcomas are much less common than carcinomas.
They are two main types:
- Bone sarcomas start from bone cells.
- Soft tissue sarcomas are rare and mostly start in cartilage or muscle.
Sarcomas are found in connective tissue that is present in a number of structures such as the
- blood vessels
- lymphatic tissue
- adipose tissue or fat.
Sarcomas make less than 1% of cancer cases diagnosed every year.
Examples of Sarcoma
- Osteosarcoma of the bone
- Liposarcoma of the adipose tissue
- Angiosarcoma of the lining of blood vessels
- Synovial sarcoma is among the rare types of cancer found in the synovial tissue of tendons, or in bursae (synovial fluid-filled sac found between bones in a joint and between tendons and/or muscles to allow free movement) or in the cavities that separate the bones in the joints.
- Fibrosarcoma is a sarcoma of the fibroblasts, which are cells that produce connective tissue. It is typically seen around bones and in soft tissue.
Cancer of the central nervous system (CNS)
These are types of cancers that originate in nervous tissue and are seen in the brain and the spinal cord. The most common type of brain tumor develops from glial cells, which are non-neuronal cells in the central nervous system.
A CNS tumor develops from the abnormal growth of cells from the tissue of the brain or the spinal cord.
Early symptoms of brain cancer include forceful vomiting, headache, nausea, visual disturbances, and seizures.
Symptoms of spinal cord tumor include back pain, difficulty in walking, loss of bladder and bowel function,
Examples of CNS cancer include:
- Tumors of the brain such as Gliomas, Astrocytomas, Ependymoma
- Meningiomas of the meninges (lining covering the brain)
- Pituitary Adenomas of the pituitary gland and
- Spinal cord tumors
Lymphoma is a cancer of the lymphatic system, which is part of the immune system. Lymphomas start in the lymph nodes or glands or the lymphocyte cells of the lymphatic system.
The lymphocytes begin to behave abnormally and proliferate rapidly and without control. They do not mature enough and therefore, lose their function. As a result, the immunity of the person falls.
Lymphoma can develop in all parts of the lymphatic system as well as other organs throughout the body. The parts of the lymphatic system include the lymph nodes, spleen, thymus gland, and bone marrow.
Lymphomas account for 4 to 5 percent of all cancers diagnosed in the UK and the USA.
Examples of Lymphomas
- Hodgkin Lymphomas
Myeloma is a cancer of the plasma cells. Plasma cells are a type of white blood cell made in the bone marrow. They produce antibodies, called immunoglobulins, that immunize our bodies against infection.
Since the plasma cells reside in the bone marrow of the large bones, myelomas develop there. They develop abnormally and multiply without control. Consequently, they do not mature, which adversely affects the immune system.
Myeloma makes up about 1% of cancer cases in the UK and 0.76% in the USA.
Examples of Myelomas
- Plasmocytoma. When myeloma occurs only in one site, it is called a plasmacytoma.
- Multiple myeloma. When it occurs at multiple sites, it is called multiple myeloma.
Metastatic cancer cells usually come from a cell type described above and these cells have now spread to a tissue in which the cancer cells did not originally develop.
For example, prostate cancer that has spread to the bone would be described as metastatic prostate cancer to bone and not bone cancer.
- Types of Cancer explained above explain the different types of cancer according to the site of origin of cancer in the various tissues of the body.
- Examples of cancer with each type of cancer are also given. The general signs and symptoms of cancer and its early warning signs do vary according to the type of cancer.
- The causes of cancer and its risk factors for each type are explained in brief in the link provided.