The majority of cancer cases can be explained by \u201cbad luck\u201d rather than the result of environmental factors and inherited genes, a US study said. The study, published in the US journal Science, found that two-thirds of adult cancer incidence across tissues might be caused by random mutations that occur in dividing healthy stem cells.\nThe findings, based on a statistical model that quantified how much of three factors — bad luck, the environment and heredity — contribute to cancer development, might help researchers design more effective prevention strategies for different cancer types.
\n\u201cChanging our lifestyle and habits will be a huge help in preventing certain cancers, but this may not be as effective for a variety of others,\u201d Xinhua quoted co-author Cristian Tomasetti, assistant professor of oncology at the Johns Hopkins University School of Medicine and Bloomberg School of Public Health, as saying. It was well-known that cancer arises when tissue-specific stem cells make random mistakes, or mutations, when one chemical letter in DNA is incorrectly swapped for another during the replication process in cell division.
\nThe more these mutations accumulate, the higher the risk that cells will grow unchecked, a hallmark of cancer. The actual contribution of these random mistakes to cancer incidence, in comparison to the contribution of hereditary or environmental factors, was not previously known.
\nIn the new study, researchers analysed published data on stem cell divisions in 31 different human tissues and compared the data to the lifetime incidence of cancer in those tissues. They determined the correlation between the total number of stem cell divisions and cancer risk to be 0.804. Using statistical theory, the pair calculated how much of the variation in cancer risk can be explained by the number of stem cell divisions, which is 0.804 squared, or, in percentage form, about 65%.
\nFurther, research found that 22 cancer types in 31 tissues could be largely explained by \u201cbad luck\u201d factor of random DNA mutations during cell division.<\/p>\n","protected":false},"excerpt":{"rendered":"