Cancer, also known as a malignant tumor or malignant neoplasm, is a group of diseases involving abnormal cell growth with the potential to invade or spread (Metastasis) to other parts of the body. 

Not all tumors are cancerous; benign tumors do not spread to other parts of the body. Possible signs and symptoms include: 

  • a new lump, 
  • abnormal bleeding, 
  • a prolonged cough,
  •  unexplained weight loss, and a 
  • change in bowel movements, among others. 

While these symptoms may indicate cancer, they may also occur due to other issues.  There are over 100 different known cancers that affect humans.


How cancer spreads via metastasis . image: National Cancer Institute / wikipedia

Origin of the word Metastasis is a Greek word meaning "displacement", from μετά, meta, "next", and στάσις, stasis, "placement”.

How cancer is defined is based on it’s overall properties. 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.

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. 

Six characteristics of cancer have been proposed:

  • self-sufficiency in growth signalling
  • insensitivity to anti-growth signals
  • evasion of apoptosis (controlled cell death)
  • enabling of a limitless replicative potential
  • induction and sustainment of angiogenesis (new blood vessels form from pre-existing vessels)
  • activation of metastasis and invasion of tissue. 

The term 'malignant progression’ is used to describe the multiple steps from normal cells to cells that can form a discernible mass to outright cancer.

source: Cancer. (2015, February 3). In Wikipedia, The Free Encyclopedia. Retrieved 23:05, February 8, 2015, from