Most cell mutations are random copying mistakes

A NEW study published suggests that cells make random mistakes while dividing, accounting for most of the mutations in tumours, rather than family history or environmental factors.

In the report in the journal Science, the scientists in the team expanded their mathematical model based on DNA sequencing and epidemiologic data to 69 countries worldwide.

“Two-thirds of the mutations that occur in cancers are due to the mistakes that cells make when they divide,” said co-author Bert Vogelstein, who is the co-director of the Ludwig Centre at the Johns Hopkins University Kimmel Cancer Centre.

Environment is a factor in 29% of the mutations in cancer, while heredity accounts for 5%, according to the study.

“Every time a perfectly normal cell divides, it makes several mistakes – mutations,” Vogelstein said.

The study also shines a spotlight on cancers that will occur no matter how perfect the environment, and may alleviate the guilt some patients face when they are diagnosed.

“These copying mistakes are a potent source of cancer mutations that historically have been scientifically undervalued,” said co-author Cristian Tomasetti, an assistant professor of biostatistics at the Johns Hopkins Kimmel Cancer Centre.

However, he still urged people to avoid known risk factors for cancer, such as smoking and too much sun exposure.

“Despite the role of the random replication component in producing mutations, you could still reduce the cancer risk hugely, for many types of cancer, by getting rid of the environmental and/or hereditary causes,” said Lawrence Young, director of the Cancer Research Centre at the University of Warwick in England. – Agencies