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How a Healthy Cell Becomes Cancerous

by Natalie Samara

Hi everyone! Since this week we are highlighting cancer, we are taking a more scientific route into how cancer cells are formed. This article takes a look into the complexities of tumor development, and how cancer can emerge from a seemingly harmless body cell.

Breast cancer, lung cancer, blood cancer—name a cell and it can turn into a cancer. But how does this process occur? How can a single healthy cell turn into a possible killer? Let’s look at how normal cells become cancerous with the different characteristics, functions, and the impact it can have on our body.

What are normal cells and what do they do for us?

Normal cells are the basic building blocks of living things, and they possess specific characteristics. This enables them to maintain normal functioning of tissues, organs, and organ systems. In response to irreparable damage, they stick together by maintaining selective adhesions. Then, they progressively adjust to ensure they remain in their intended location. Finally, they differentiate into specialized cells with specific functions meaning they can adopt different physical characteristics despite having the same genome. When necessary, they also undergo programmed cell death, also known as “apoptosis.” Apoptosis is part of normal cell development and helps maintain tissue homeostasis.

What are cancerous cells?

Cancer as we know is a genetic disease caused by the specific changes to the genes in one or a group of cells. This disrupts the function of the cell—specifically how it grows and divides. The thing that cancer cells do that are different from normal cells, they never stop growing and dividing, which results in the formation of a tumor. These cells have more genetic changes than normal cells, but not all of these changes result in the development of cancer. When necessary, the cells also undergo programmed cell death, also known as “apoptosis”, and the goes through homeostasis which is a process that living organisms use to actively maintain stable conditions necessary for survival.

The differences between a normal and cancerous cell

Here is a diagram of what a normal and cancerous cell looks like:

Normal Cell Cancerous Cell

Cell Shape:




Spheroid shape, single nucleus

Irregular shape, multi-nucleation common


Fine, evenly distributed

Coarse, aggregated


Single, inconspicuous nucleolus

Multiple, enlarged nucleoli


Large cytoplasmic volume

Small cytoplasmic volume





Mature into specialized cells

Remain immature and undifferentiated

Blood Supply

Normal angiogenesis (occurs during development/ healing)


Favored (for aerobic respiration) but will undergo anaerobic respiration if required

Not required (thrive in hypoxic conditions), favor anaerobic respiration


Remain in their intended location

Can spread to different locations in the body (metastasis)

How does cancer start?

Normal cells grow and divide only to replace the aging or damaged cells. Cancer cells, however, are mutated. The mutations are either inherited, developed as we age, or incurred from agents in our environment, like smoke, alcohol, or ultraviolet radiation (UV) from the sun. The cell continues to grow and divide. As the cancer cells divide, a tumor grows in the body. A small tumor can easily grow and get oxygen and nutrients from existing blood vessels. As the tumor grows, it needs more nutrition. So, cancer cells signal the tumor to make new blood vessels. This is referred to as “angiogenesis”, where the formation of new blood cells comes, and it is one route of tumor growth. Moreover, it allows cancer cells to enter the bloodstream and spread to other parts of the body.

How does it spread in the body?

As the tumor gets bigger, the cancer cells push on the normal tissue beside the tumor. They also make enzymes that break down the normal cells and tissues as they grow. Cancer cells can also break off from the tumor and travel through the lymphatic system. Consequently, the cancer cells can spread to other parts of the body in a process called “metastasis.” Metastasis means that cells can spread from one part of the body to another part and form secondary tumors. Cancer is serious enough, but it can become even graver should it spread to critical organs.

We hope you enjoyed reading the second article in our Cancer week! If you liked reading about this article, go read Nihitha's article on how cancer impacted her cousin's life, linked here. This article is very touching and is truly shows how much cancer can shape an individual's life in various ways.

if you are interested in becoming a writer, or have any questions about the Writing Committee, please feel free to comment down below, or email

Thanks for reading and please stay tuned for our upcoming articles!

Happy Reading,

Natalie and the Writing Committee :)


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