The short answer
Most cancers fall into a few broad families named for the cell they start in: carcinomas (skin and organ linings), sarcomas (bone and soft tissue), leukemias (blood), and lymphomas (immune system).
Cancers are grouped by the type of cell where they begin.
Carcinomas start in the cells that line skin and internal organs and are the most common.
Sarcomas start in bone or soft tissues like muscle, fat, and cartilage.
Leukemias start in blood-forming tissue; lymphomas start in immune-system cells.
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The full explanation.
Named for where they start
There are more than 100 kinds of cancer, but most fall into a few broad families. The family a cancer belongs to is decided by the type of cell where it began — not the organ alone. This is why two cancers in the same organ can behave very differently.
Carcinoma
Carcinomas are the most common cancers. They begin in epithelial cells — the cells that make up skin and the linings of organs and glands. Most breast, lung, colon, and prostate cancers are carcinomas.
Sarcoma
Sarcomas begin in bone or in soft tissues such as muscle, fat, blood vessels, nerves, or cartilage. They are far less common than carcinomas and are often treated at specialized centers.
Leukemia
Leukemias start in blood-forming tissue, such as the bone marrow, and lead to large numbers of abnormal blood cells. They usually do not form a solid tumor you can feel.
Lymphoma and myeloma
Lymphomas begin in lymphocytes, a type of white blood cell that is part of the immune system, and often show up as swollen lymph nodes. Myeloma begins in plasma cells, another immune cell. Both are cancers of the immune system's cells.
Words to know
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Common questions
▸What is a carcinoma?
A carcinoma is a cancer that begins in epithelial cells — the cells that cover the skin and line the inside of organs and glands. Most cancers, including most breast, lung, colon, and prostate cancers, are carcinomas.
▸What is a sarcoma?
A sarcoma is a cancer that starts in bone or in soft tissues such as muscle, fat, blood vessels, or cartilage. Sarcomas are much less common than carcinomas.
▸How are leukemia and lymphoma different?
Leukemia starts in blood-forming tissue such as bone marrow and usually does not form a solid lump. Lymphoma starts in lymphocytes, a type of immune cell, and often forms masses in lymph nodes.
▸Why does the cell type matter?
Cancers from different cell types tend to grow and spread differently and respond to different treatments, so naming the cell type helps guide care.
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