Cancer Mutations Mostly Due to 'Bad Luck' -- New Data

medscape.com - Again the question asserts itself — are many cancers simply due to "bad luck"?

Two years ago, the media went into a tailspin over a research article in Science that suggested that many cancer types can be chalked up to random mutations, or simply "bad luck."

It led to quite a bit of discussion, as well as many questions regarding the underlying methods and calculations.

The same authors have now published a second study that supports their earlier conclusions.

For the new study, also published in Science, the researchers analyzed genome sequencing and epidemiologic data from 32 cancer types and concluded that DNA replication errors (R) are responsible for about two thirds of the mutations in human cancers.

This is a "complete paradigm shift in how we think of cancer," coauthor Cristian Tomasetti, PhD, assistant professor of biostatistics at the Johns Hopkins Kimmel Cancer Center and the Johns Hopkins Bloomberg School of Public Health, in Baltimore, Maryland, said during a press briefing. "The 65% says that the R component is here to stay, and it is a major one."

It suggests that 65% of cancer is due to chance, or "bad luck" – which is the same message that caused such an uproar when it was initially suggested by the first study.

An introduction to the article helps to explain why – "most textbooks attribute cancer-causing mutations to two major sources: inherited and environmental factors." These new studies highlight the prominent role of R mutations in cancer. These mutations arise from a third source: unavoidable errors associated with DNA replication.

At the press briefing, Dr Tomasettie and coauthor Bert Vogelstein, MD, codirector of the Ludwig Center at the Johns Hopkins Kimmel Cancer Center, went on to reconcile the two different ways of thinking. They emphasized that their findings are consistent with epidemiologic studies suggesting that about 40% of cancers can be prevented by changes in the environment.

These findings do not negate the importance of factors such as diet, exercise, and smoking, which contribute to cancer development, they said.

"Mutations are unavoidable, and cancers to some extent are unavoidable," Dr Vogelstein told journalists. "It doesn't mean that we should add to that by smoking or exposure to other noxious influences."

However, many people will develop cancers because of these random DNA copying errors, regardless of environmental factors. (ontinueReading