What is cancer?

“What is cancer and what causes it?” is easily asked and often thought to have a simple answer, but a detailed response could fill several volumes. Even the most complex phenomena need a definition. For cancer, it is: Cancer is the general name for diseases arising from irregular cell proliferation caused by accumulated DNA damage.

What is a tumor?

A tumor, also called a neoplasm, is an abnormal tissue mass that may be solid or fluid-filled. Not every tumor is cancer. Tumors can be: - benign (noncancerous), - premalignant (not currently cancerous but with the potential to become cancerous), or - malignant (cancerous). Many tumor types have different names, usually reflecting shape and appearance within tissue. Simply put, a tumor is a kind of lump or swelling that does not necessarily threaten health.

Groups of cells that multiply excessively and uncontrollably, spread locally or can metastasize are called cancer .

For a much more detailed explanation of how cancer develops, see WHAT IS CANCER? Why and how does it develop? in our article.