Cancer is an uncontrolled proliferation of cells growing abnormally in the body. The transformation of a normal cell into a cancer cell is result of genetic alterations that will gradually disrupt the control systems of the cell.
The term cancer includes a set of conditions. There are over a hundred types of cancer.

Almost all tissues of our body can be affected by this disorder whose causes, trends and consequences are very different.

How does a cell become cancerous?

Healthy cells, which are the basic element of tissue, arise, divide and replace themselves in an orderly fashion following a specific program defined by their genetic heritage. This process allows the body to maintain balance.
Sometimes, however, certain cells lose their ability to controlled growth: they divide too rapidly and grow in a disorderly fashion, forming a lump called a tumor.

However, all tumors are not cancerous. If the growth stops, it is not cancer but a normal phenomenon.
But in some cases, the tumor may progress to carcinoma in situ, ie localized cancer.
When the cells continue to divide uncontrollably, the local tumor grows at the expense of tissues and organs surrounding healthy. To further develop the tumor produces substances causing blood vessels to supply it with energy. This is called neovascularization of tumors.
In passing through the blood or lymphatic system, tumor cells can spread to other parts of the body to form new tumors. This is called metastasis. The cancer becomes invasive.
So even if an initial cancerous tumor is removed, the disease may thus recur. This ability to spread throughout the body that it is essential to detect the earliest possible tumor and whether it is benign or malignant.
In all cases, effective treatments, to control the disease are possible once the diagnosis of cancer is raised.