Cancer: facts and causes

Cancer is a class of diseases characterized by out-of-control cell growth. There are over 100 different types of cancer, and each one is classified by the type of cell that is initially affected.


1.    a cancerous cell manages to move throughout the body using the blood or lymphatic systems, destroying healthy tissue in a process called invasion

According to the American Cancer Society, Cancer is the second most common cause of death in the US and accounts for nearly 1 of every 4 deaths. The World Health Organisation estimates that, worldwide, there were 4 million new cancer cases and 8.2 million cancer-related deaths in 2012 (their most recent data).

How cancer spreads

Scientists reported in Nature Communications (October 2012 issue) that they have discovered an important clue as to why cancer cells spread. It has something to do with their adhesion (stickiness) properties. Certain molecular interactions between cells and the scaffolding that holds them in place (extracellular matrix) cause them to become unstuck at the original tumor site, they become dislodged, move on and then reattach themselves at a new site.

The researchers say this discovery is important because cancer mortality is mainly due to metastatic tumors, those that grow from cells that have traveled from their original site to another part of the body. These are called secondary tumors. Only 10% of cancer deaths are caused by the primary tumors.

The scientists, from the Massachusetts Institute of Technology, say that finding a way to stop cancer cells from sticking to new sites could interfere with metastatic disease, and halt the growth of secondary tumors.
Malignant cells and non-malignant cells

Scientists from the Physical Sciences-Oncology Centers, USA, reported in the journal Scientific Reports (April 2013 issue) that malignant cells are much “nimbler” than non-malignant ones. Malignant cells can pass more easily through smaller gaps, as well as applying a much greater force on their environment compared to other cells. Professor Robert Austin and team created a new catalogue of the physical and chemical features of cancerous cells with over 100 scientists from 20 different centers across the United States.

The authors believe their catalogue will help oncologists detect cancerous cells in patients early on, thus preventing the spread of the disease to other parts of the body. Prof. Austin said "By bringing together different types of experimental expertise to systematically compare metastatic and non-metastatic cells, we have advanced our knowledge of how metastasis occurs."

Causes of cancer


Genes and DNA

Cells can experience uncontrolled growth if there are mutations to DNA, and therefore, alterations to the genes involved in cell division. Four key types of gene are responsible for the cell division process: oncogenes tell cells when to divide, tumor suppressor genes tell cells when not to divide, suicide genes control apoptosis and tell the cell to kill itself if something goes wrong, and DNA-repair genes instruct a cell to repair damaged DNA.




Genetic predisposition


Cancer and other medical factors


Author: Peter Crosta / Sept. 2015
Text abridged and adapted / Dec. 2015
With kind permission to publish from MNT
