Cancer is the uncontrolled growth of abnormal cells anywhere in a body. These abnormal cells are termed cancer cells, malignant cells, or tumor cells. These cells can infiltrate normal body tissues. Many cancers and the abnormal cells that compose the cancer tissue are further identified by the name of the tissue that the abnormal cells originated from (for example, breast cancer, lung cancer, colon cancer). Cancer is not confined to humans; animals and other living organisms can get cancer. Below is a schematic that shows normal cell division and how when a cell is damaged or altered without repair to its system, the cell usually dies. Also shown is what occurs when such damaged or unrepaired cells do not die and become cancer cells and show uncontrolled division and growth — a mass of cancer cells develop. Frequently, cancer cells can break away from this original mass of cells, travel through the blood and lymph systems, and lodge in other organs where they can again repeat the uncontrolled growth cycle. This process of cancer cells leaving an area and growing in another body area is termed metastatic spread or metastasis. For example, if breast cancer cells spread to a bone, it means that the individual has metastatic breast cancer to bone. This is not the same as “bone cancer,” which would mean the cancer had started in the bone.
The following table (National Cancer Institute 2016) gives the estimated numbers of new cases and deaths for each common cancer type:
|Cancer Type||Estimated New Cases||Estimated Deaths|
|Breast (Female — Male)||246,660 — 2,600||40,450 — 440|
|Colon and Rectal (Combined)||134,490||49,190|
|Kidney (Renal Cell and Renal Pelvis) Cancer||62,700||14,240|
|Leukemia (All Types)||60,140||24,400|
|Lung (Including Bronchus)||224,390||158,080|