Cancer & DNA Mistakes

A new study has found that in most cancer cases, it is caused by DNA mistakes that are completely random. Cancer may not always be due to heredity or environmental factors, but the result of random errors.

The mutations, or mistakes, can cause cancer to happen as even just a tiny error in our DNA can make the cells multiply and go out of control. These mutations were thought by the scientists to result mainly from either the mutation being inherited, or it was caused by outside factors that can damage the DNA. Examples of that could be cigarette smoke or ultraviolet radiation.

There is a third cause that actually counts for 2/3s of these mutations and that is random mistakes. The new study was published in the journal Science. When a cell divides, it then copies its own DNA so each of the new cells will have its own version of the genetic material. This also creates an opportunity for mistakes to occur that can lead to cancer.

Cancer will occur no matter how perfect the environment is, according to senior study author Dr. Bert Vogelstein, a pathologist at the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University. Researchers sought to calculate what percentages of cancers were due to heredity, environment and random mistakes. They then developed a mathematical model that used data from registries of cancer patients around the world and data from DNA sequencing.

It resulted in 66% of cancers due to random mistakes, 29% to environmental factors or lifestyles, and 5% due to inherited mutations. Researchers found this lined up somewhat with an estimate from Cancer Research UK that 42% of cancers could be prevented with changes to lifestyle.

Brain and prostate cancer are nearly all attributed to random mistakes and had caused more than 95% of these cancer cases looked at in the study. Environmental factors play a large role in other cancers. Smoking and environmental factors caused 65% of all lung cancers and 35% were due to random mistakes. Mutation in a single cell is unlikely to cause cancer, but the more mutations there are, the more likely it is that the cell will turn cancerous.

These caused by random mistakes are enough to cause cancer by themselves, but in other cases, a combination of random mistakes plus those due to environmental factors turn the cells cancerous. Cristian Tomasetti, an assistant professor of biostatistics at Johns Hopkins believes the three causes of mutations are due to typos that occur while using a keyboard. No matter what, keyboard typos will occur and represent random mistakes.

Using primary prevention strategies are the best way to reduce deaths from cancers, but secondary prevention can help save lives. Early detection must be our primary focus.

Dr Fredda Branyon