Cancer has different forms in different tissues but most of the cancers have some common biological properties such as unrestrained cell division; lack of cell maturation; loss of the normal cellular functions; and invasive behaviour of the cells. The four major attributes that differentiate the cancerous cells from normal cells of the body are clonality, autonomy, anaplasia and metastasis.
Clonality: Cancer cells multiply to form clones.
Autonomy: Cancer cells are not regulated by the body.
Anaplasia: Cancer cells do not have cellular differentiation.
Metastasis: Cancer cells can grow in other tissues and organs of the body.
Cancer biologists, Robert Weinberg & Douglas Hanahan published an article “The Hallmarks of Cancer” in January 2000 that identified six essential traits of human cancer cells, which include:
- Pathological mitosis by activation of oncogenes (such as ras or myc).
- Inactivation of tumour suppressor genes (such as Rb) that normally inhibit abnormal cell growth.
- Evasion of programmed cell death (apoptosis).
- Acquire potential of limitless replication making cancer cells immortal.
- Tumour angiogenesis
- Migration to other organs, invade their tissues and colonise these organs (tissue invasion and metastasis).