Why do benign tumours quit growing? Isn’t it possible that understanding benign tumours and why they are not life-threatening could help treat malignant growths?
• There is really no such thing as a “benign” or “malignant” tumour. All cancerous, or neoplastic, growths exist on a spectrum. What we tend to mean when we describe a tumour as benign is that it is unlikely to spread to other parts of the body or metastasise.
Benign tumours tend to have a capsule that keeps them in situ, whereas malignant growths penetrate the basement membrane that separates different tissue types before spreading through the blood or lymph systems.
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Although benign tumours do not metastasise, they are actually far from harmless. Their continued growth can put pressure on organs, nerves or blood vessels, and can also cause significant tissue damage.
“Although benign tumours do not spread to other parts of the body, they are far from harmless”
Endocrine tumours can produce vast quantities of hormones, which can be very harmful and may even induce other cancers in the individual. So a benign growth can cause significant health problems.
Benign growths can also eventually become malignant. Hepatic adenomas are primary neoplasms of liver cells called that are considered to be benign. But a mutation in the gene for the protein catenin is linked to a greater chance of their transformation into a malignant state.
The longer any benign disease is allowed to progress, of course, the greater the chance of the disease ultimately becoming malignant, which is why there is no true distinction.
Sub-classification of tumours based upon gene expression is important for accurate prognosis and treatment options. Be reassured that the genetic pathways leading to neoplasms are areas of a great deal of research and are already leading to better treatment of neoplastic disease.
Chris Starling, Biomedical Scientist, Institute of Liver Studies, King’s College Hospital, London, UK