Everyone you ask will have something slightly different to say about what cancer is to them. Some would say its a disease. Others might tell you a personal story of someone they know with cancer, or maybe even their own experience. Others still might dive into the complicated and dynamic world of cancer research, new data, studies, and treatments. We have movies, books, even songs about cancer, and yet the disease itself can often seem like a big black cloud of the unknown. So, what is cancer really?
To understand the basics of the disease, we must first realize that our bodies are made up of millions of cells. These cells are like tiny individual machines that work together to perform the tasks required for our bodies to function. For example, the myocytes that make up our muscle can contract to allow for movement, and the neurons in our brain and nerves can transmit information through electrical impulses. All these cells — at some point in their lifecycles — contain DNA, or deoxyribonucleic acid, which functions as a blueprint or instruction manual for the cells to function. You can probably recognize DNA's unique form in the initial artwork on this page: a double helix that is formed from 2 polynucleotide chains.
DNA encodes for specific proteins, which can determine everything from the colour of our eyes, to how fast our cells can grow and divide. When things go right, DNA is like a blueprint from which our bodies are built. But when things go wrong, the result can be cancer.
You see, DNA can be thought of like a jigsaw puzzle, composted of many small pieces to form a larger picture. If you are missing too many pieces, or add more pieces than come in the box, or put together the pieces in a way different from how they’re meant to fit, the final product will be different from how it is supposed to look. And if you make too many errors, the final product may not even be recognizable at all. When the same thing happens to our DNA, the resulting proteins can look very different from what was intended. They can function differently, or not function at all.
When this happens to the proteins that are involved in controlling how our cells grow and divide, the result can sometimes be uncontrolled replication. Normally, the cells in our body will only divide when needed, and if they become damaged or dysfunctional they will die. But if the checkpoints in place for this process fail, the result can be cells that keep on dividing, and no longer listen to the signals intended to keep them in line. These abnormal cells can form tumors, and if they spread or invade other tissues, they are considered cancerous. Another word for cancerous is malignant.
Cancer cells differ from healthy cells in several ways, but one of the most important concepts is that they no longer require signals to mature or divide like our normal cells do. This can often allow for them to grow and spread rapidly, invading healthy tissue and consuming the body’s energy supplies. Cancer cells can also sometimes manipulate our immune systems, and even our blood vessels to prevent being targeted by our bodies and to facilitate further growth. Secondly, cancer cells often do not function like the healthy cells from which they originated. The consequences of this can be deadly when the burden of cancer on the body is too high.
It is important to note that cancer can arise from many different tissues, and different types of cancer can behave very differently from each other. Now that we have gone over the basics of what cancer is, future pages will dive into specific cancer diagnoses and the current practices surrounding them.
References:
1. Patel, M., Chawla, N., & Surani, Z. (2017). Cancer. In Health of South Asians in the United States (pp. 47-69). CRC Press.
2. Weinberg, R. A. (1996). How cancer arises. Scientific American, 275(3), 62-70.
3. www.cancer.gov/about-cancer/understanding/what-is-cancer
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