Cancers are classified according to:
- Site: part of the body where cancer first develops (primary site).
- Cell type: which type of cell the cancer started from.
A. Cancer by site
- Colon and rectum.
B. Cancer by cell type
- Epithelial: cells that cover the outside part of the body (skin) and make tissues covering the organs.
- Mesenchymal: connective tissue cells which functions are to support and connect tissues such as muscles, bones and fatty tissue.
- Mesenchymal and hematopoietic: cells from the blood and lymphatic system.
- Neuroectodermal: cells from the peripheral and central nervous system.
Depending on where cancers start in each of these cell types, a different name is given:
This type of cancer starts in epithelial cells. The majority of tumours come from epithelial cells (85%). However, there are different types of epithelial cells:
- Squamous cells
- Adeno cells.
- Urothelial cells (transitional).
- Basal cells.
2. Leukaemias and lymphomas
Leukaemias are developed in the blood and bone marrow (site where white blood cells are formed to fight infection in the body). In contrast, lymphomas are formed in the lymphatic system (part of the body which helps to fight infection).
These types of cancers only represent the 7%.
In this case, the cancer starts in connective tissue cells. Sarcomas are quite rare (1% of cancers) and are divided in two types:
- Bone sarcomas: found in the bones.
- Soft tissue sarcomas: developed in other body supportive tissues.
Other cancers can develop in other types of cells such as brain cancers.
For more information about cancer types, see this website: http://www.macmillan.org.uk/Cancerinformation/Aboutcancer/Typesofcancer.aspx
In this picture, I would like to show you the association between different types of tumours. You can observe that primary tumours also have their metastatic tropisms.
The most common affectation in prostate cancer and breast cancer is the bone marrow.
In colon cancer and pancreas cancer it is common to find tumours in the liver.
Thanks to different techniques, it can be known whether a tumour is a metastasis of another. For example, we can associate that a brain cancer is a metastasis from a breast cancer.
The most wide spread types of cancer are:
- Lung cancer.
- Breast cancer.
- Colorectal cancer.
- Stomach cancer.
- Prostate cancer.