Definitions
Cancers are a large family of diseases that involve abnormal cell growth with the potential to invade or spread to other parts of the body.[1][2] They form a subset of neoplasms. A neoplasm or tumor is a group of cells that have undergone unregulated growth, and will often form a mass or lump, but may be distributed diffusely.[21][22]
All tumor cells show the six hallmarks of cancer. These are characteristics that the cancer cells need to produce a malignant tumor. They include:[23]
Cell growth and division without the proper signals to do so
Continuous growth and division even when there are signals telling them to stop
Avoidance of programmed cell death
Limitless number of cell divisions
Promoting blood vessel construction
Invasion of tissue and formation of metastases[24]
The progression from normal cells to cells that can form a detectable mass to outright cancer involves multiple steps known as malignant progression.[24][