Text Size: A | A | A
Home > Your diagnosis > How cancer develops

How cancer develops

Every day, researchers are learning more about the causes of cancer.

Many people tend to think of cancer as one disease. But the word cancer describes a large group of diseases that have certain traits in common, yet exhibit distinctive characteristics. In fact, there are over 200 known types of cancer that all behave in different ways, grow at different rates, and respond to different types of treatment. But what all cancers have in common is the growth of abnormal cells in the body. They replicate rapidly, are difficult to destroy, and can overwhelm normal, healthy cells.

Cells by the numbers

Like all living organisms, your body consists of cells. The average human body is made up of about 60 trillion cells. Some of these cells divide constantly to replace worn out or damaged cells in an orderly, regulated way.

Out of all the billions of cells that your body creates each day, it’s no wonder that it makes mistakes from time to time and creates abnormal cells. Usually your immune system recognizes these cells and repairs or eliminates them. In fact, many researchers believe that everyone develops pre-cancerous cells during his or her lifetime, yet less than half the population ever develops cancer. Most of the time, damaged cells simply stop reproducing on their own or form tiny, harmless — or benign — tumors within the body.

Why me?

Why do some people develop cancer while others don’t? Researchers are still trying to answer this question.

Cancer develops when DNA gets damaged, causing a genetic mutation. DNA is the primary genetic material inside every cell that influences everything it does.

But sometimes, when damage to a cell’s DNA cannot be repaired, a process is activated that causes the cell to reproduce uncontrollably. Scientists have compared this process to a switch being flipped from “off ” to “on.” Eventually the number of mutated cells becomes large enough to form a solid tumor or a cancer like leukemia that travels throughout the body.

DNA can become damaged in a variety of ways and increase your risk of cancer. Some people may inherit damaged DNA genetically, making it more likely that they will develop certain types of cancer. Genetic factors are responsible for up to 10% of all cancers depending on the type. The other 90% are caused by environmental and lifestyle factors that you may or may not be able to control.

However, just because you inherit a genetic predisposition doesn’t necessarily mean you’re predestined to develop a certain kind of cancer. In the majority of cases, cancer develops because of a mysterious interaction of different factors. So while you may have a genetic tendency for cancer, that doesn’t always mean you’re fated to develop it.

Similarly, inheriting a genetic mutation isn’t the same thing as having a family history of cancer. Lifestyle and environmental influences, such as dietary habits that are passed down from one generation to the next or exposure to secondhand smoke in the household may have more to do with a family history of cancer than genetics.

Toxic overload

Healthy cells can become damaged because of poor dietary habits, smoking, or a sedentary lifestyle. Environmental factors, such as poor air quality, secondhand smoke, or exposure to carcinogens at work can raise your risk. Additives, pesticides, and artificial hormones in food also play a role. Even living in an urban environment can increase the likelihood of developing cancer. These toxins can damage your cellular structure, impair your immune system, and overtax your body’s natural ability to rid itself of poisons and waste products. Even the stresses of modern life may affect your health.

The good news is that whether or not your risk for cancer is inherited, making positive lifestyle changes can reduce your chances of developing the disease. If you’ve been diagnosed, making healthy lifestyle choices may increase your chances of being cured, plus help you to live longer and feel better.