Cancer, just a case of bad luck?

We can all agree on the fact that good lifestyle choices such as avoiding smoking, eating a balanced diet and having daily exercise will offer you some protection from developing cancer. However, how much protection it will offer you exactly has never been entirely clear. Is it all worth it, or is all your good behaviour sticking to a healthy lifestyle just a waste of time and effort?

I started to ask myself these questions after reading a study from researchers from the Johns Hopskins University. This study showed that only 9 cancers from the 31 different cancers that were studied, were due to inheritance or poor lifestyle choices. So, simply put, when we manage to resist the temptation to take another snack or another cigarette it will not change the odds of developing at least 22 different cancers. But where do these cancers ‘come from’ and can we prevent them in a different way?

The answer lies in the way our bodies regenerate. A very carefully controlled process, whereby cells divide to produce new cells, allows our body to grow. During adult life it is the division of stem cells that allows our body to repair itself by replacing damaged or lost cells. Stem cells are undifferentiated cells that can differentiate into many different specialized cells and have the ability to go through numerous cycles of cell division, called self-renewal. When a stem cell divides, the DNA within this stem cell has to be copied, or replicated, and to be distributed over the two new cells, so that both will contain the same genetic information that lies in the DNA. Although it is a very carefully controlled process, random mistakes, or mutations, can occur during stem cell division. A mutation is a change in the DNA sequence; a chemical letter is incorrectly swapped for another chemical letter during replication. In the figure below you can see an example of such a random mutation in a piece of DNA sequence.

                       Fig.1: An example of a random mutation in the DNA sequence. A 

                       chemical letter is incorrectly swapped by another chemical letter 

                       during the replication process, or the copying process, of the DNA.

The more these mutations accumulate, the higher the risk that cells will grow in an uncontrolled way, which is a hallmark for cancer. During aging your stem cells keep dividing and dividing, which means more chance of random mutations and thus more chance of development of cancer stem cells. Bad luck. But how can we prevent ourselves from something so unpredictable such as bad luck?

For now, we cannot prevent ourselves from the random mutations due to bad luck by just optimizing our environmental factors and lifestyle choices, called primary prevention. However, since the study of the Johns Hopskins University says that two-thirds of cancer incidence is explained by random DNA mutations in stem cells, it is necessary that scientist focus more resources on finding ways to detect such cancers at early stage, called secondary prevention. Besides, according to the cancer stem cell theory, the stem cells in a tumour can cause relapse and spread of the cancer by giving rise to new tumours. Therefor detection at an early and curable stage is very important as well, so the tumour can be treated before it totally escalates.  

Do not misunderstand me by thinking that two-thirds of cancer cases are due to bad luck only. Cancer is always caused by a combination of many factors such as environmental factors, lifestyle choices and bad luck. But for two-third of the studied cancer types bad luck, or the random mutations, was the major contributing factor. Notice that still for one-third of the cancer cases, the environmental factors and lifestyle choices were the most involved factors.

In short, your good behaviour sticking to a healthy lifestyle is not a waste of time and effort, and is surely all worth it. Still a third of cancers, mainly skin cancer and long cancer, can be prevented by choices as quitting smoking, cutting back on alcohol, eating a healthy diet and avoiding too much sunlight. These good lifestyle choices can also prevent the other two-third of cancer cases if you are the lucky one that has no bad luck. So my advice: stay healthy & lucky!

                                                                                                                       By Dide Dijkstra