Image by National Cancer Institute


Cancer starts within the building blocks of life; cells. Generally, a cell's  lifecycle should be pretty basic:

A new cell is formed when either one cell divides, or two cells join. (In humans, the only time two cells join to make a new cell is in the instance of sperm and egg.) The rest of the cells in humans are formed when one cell divides, creating two identical copies..This happens over and over and over.

Each new cell does their job, pays their taxes, then dies....making room for the upcoming cells. (The true circle of life, as we know it, right?) 

There are specific proteins are in charge of this whole process, from cell birth to death. The proteins signal to the cell when its time for it's next action, whatever that is. If a mutation occurs in the genes of these proteins, however; their ability to carry out their role correctly is hindered. 

When such mutations prevent the protein from maintaining control, the cells go unchecked, and their behavior becomes erratic and unruly ....much like a scene straight from the Old Testament:

-Wild cells procreating uncontrollably,

-Damaged cells begetting more damaged cells.

-Entitled cells, feeding off the demise of others,

-Mutant cells living unnaturally too long, and, eventually,

- All the "wicked cells" increase in number, and ultimately suffocate the healthy cells.

This uninhibited cell lifestyle can lead to cancer.

Biologists have laboriously studied the mechanisms of how cells become cancerous, and found that ALL cancers involve uncontrolled cell division and tissue invasiveness (metastasis) caused by the mutations in the genes of their regulating proteins. These mutations typically involve either controlling how much and how often cells divide, or the timing of when the cell should die.  

Too much cell growth and new cell formation can produce a mass of cells...or a tumor. Cells living too long can also cause problems, as  programmed cell death plays the very important role of population control by balancing cell growth and multiplication, and  eliminating unnecessary cells.

For example, during embryonic development, the digits of our fingers and toes are sculpted by the death of cells in the intervening spaces. If these cells remained alive, our hands and feet would become webbed. Here. especially, we see how important and delicate a cell's lifecycle is, and why it must be precisely controlled.

What causes the gene mutations in the controlling proteins? The answer is short, but expansive....

There are two types of mutations:

Germline- this was passed down from mom or dad, as there was a mutation either in the sperm or egg, and it becomes copied into every cell of the embryo's body. 

Acquired-this is due to gene damage that occurs during a person's life- not something passed on from parents. Different factors that can cause this type of mutation are:


-Ultra Violet Radiation 


- Age

In the long scope of life, the reality is that mutations happen often. They can be helpful, harmful, or neutral, depending on where in the gene a mutation occurs. Typically, our bodies correct most mutations, and a single mutation won't likely cause cancer, as it's usually from built up mutations. (This is why we see a lot of cancer in older people, they've had more opportunities for mutations to accumulate. )

If you're interested in learning more about the genetics of cancer:


Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology. 4th edition. New York: W. H. Freeman; 2000. Section 1.4, The Life Cycle of Cells. Available from: https://www.ncbi.nlm.nih.gov/books/NBK21685/

cancer.net- The Genetics of Cancer