There are different types of cells in the body and each has a certain function to perform. Normal cells divide in a uniform way and when they are damaged or die, new cells take their place. The cells become cancerous when they grow out of control due to genetic mutations in the DNA. When these cancer cells continuously multiply to form a tumour, they rapidly change, becoming different from each other.

The types of cancer depends on the types of cells they originate from. On a broader scale, it is also categorised depending on the organ/site where the cancer starts, as similar signs and symptoms are shown on the basis of its origin. This helps the researchers and oncologists group cancers into different stages and types, and help organise their screening, diagnostic and treatment protocols.

Cancer is an umbrella term for a number of diseases caused due to genetic mutations and the rapid growth of cancerous cells. Their occurrence may be possible in any part of the body, making it among the deadliest diseases. The cancers are classified based on 

• The kind of cells from which they originate.
• The location or the organ in the body where they first developed.

Based on the tissues and cells it occurs, the types of cancer can be broadly classified into five categories –

Carcinoma

Carcinomas are the most common type of cancers. This type of cancer starts in epithelial tissues. They cover the outside of the body as the skin. They also cover and line all the organs inside the body, such as the organs of the digestive system. And they line the body cavities, such as the inside of the chest cavity and the abdominal cavity.

There are different types of epithelial cells, which can develop into different types of Carcinoma. 

Squamous cell carcinoma – This type of cancer starts in the squamous cells which are flat and present in the skin, lining of the throat, or esophagus. 

Adenocarcinoma – This type of cancer starts from the adenomatous cells or glandular cells that produce the fluids to keep the tissues moist. These cells usually line the stomach, uterus 

Basal cell carcinoma – Basal cell carcinoma starts in the deepest layer of skin, where the basal cells are present.

Transitional cell carcinoma – These are the cells that form tissues that can stretch as the organ expands, like in the lining of the bladder. Cancer starting from such cells is Transitional cell carcinoma.

Sarcoma

Sarcomas begin from the bone or the soft tissues of the body, including cartilage, fat, muscle, tendons, fibrous tissues and other connective tissue. 

Sarcomas are comparatively rare in occurrence and are classified into two categories.

Soft tissue sarcoma – Soft tissue sarcoma is relatively rare and the most common types occur in arms, legs, and abdomen. There are about 50 subtypes of Soft tissue sarcoma.

Bone sarcoma – Sarcomas of bone start from osteocytes or the bone cells.

Leukaemia and Myeloma

Bone marrow is responsible for the production of different blood cells like RBC (Red Blood Cells), WBC (White Blood Cells) and platelets. Leukemia is a condition where the bone marrow produces way more WBC than normal. The blood cells are not fully formed and hence don’t function properly. As the condition progresses, these abnormal cells build up in the blood. Its types include

Acute Lymphocytic Leukaemia (ALL) – Acute lymphoblastic leukaemia (ALL) is a type of blood cancer that starts from young white blood cells called lymphocytes in the bone marrow. Adults and children can get it but it is most often diagnosed in younger people.

Acute Myeloid Leukemia (AML) – AML is a type of blood cancer that starts from young white blood cells called granulocytes or monocytes in the bone marrow. It has 8 subtypes depending on the cells that leukemia (abnormal cells) developed from. 

Chronic lymphocytic leukemia (CLL) – Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. It’s a type of cancer that starts in certain white blood cells (called lymphocytes) of the bone marrow. Cancer (leukemia) cells start in the bone marrow but then go into the blood.

Chronic myeloid leukemia (CML) – This condition begins in the blood-forming cells of the bone marrow and eventually spreads into the blood and other organs over time. CML occurs mostly in adults, with rare occurrence among children too. 

Myeloma – This is a cancer that starts in the plasma cells which produce antibodies called immunoglobulins that help fight infection. Once they multiply abnormally, they start making a type of antibody that cannot properly fight an infection.

Lymphomas

These are the types of cancers that begin in the lymphatic system of the body. The lymphatic system is responsible for transporting lymph, a fluid containing infection-fighting WBCs throughout the body.

When some lymphocytes start dividing abnormally and don’t die, they crowd the healthy cells and can’t fight infection as they are premature. These abnormal lymphocytes accumulate in the lymph nodes or other places such as the bone marrow or spleen, which potentially grow into tumors.

Tumors of the Brain and Spinal cords

Tumors can also start in the brain and the spinal cord, which makes up the central nervous system. The most common form of brain tumor is known as Glioma, which is developed from glial cells in the brain.  Some tumors of the brain and spinal cord are slow-growing and stay potentially unharmful for a lifetime.

When it comes to the place and the position it occurs, there are over 100 types of cancers.