Environmental and external factors such as smoking, drinking, sun exposure and pollution may account for up to nine out of 10 cancers, a new study has claimed. It was previously believed that random cell mutations played a significant role in development of tumours.
However, scientists at the Stony Brook University now believe that our lifestyle has a greater impact, meaning cancers may be more preventable than previously thought.
The researchers said cancer incidence is far too high to be explained by simple mutations in cell division. Intrinsic risk factors contribute only modestly to cancer development. The rate of mutation accumulation by intrinsic processes are not sufficient to account for cancer risks.
Previous studies have shown how immigrants moving from low cancer incidence countries to countries with high cancer incidence soon develop the same tumour rates, suggesting the risks are environmental rather than biological or genetic.
“For many common types of cancer, this study concludes that at least 70% to 90% of the cancers are due to external risk factors,“ said Kevin McConway from the Open University . According to the new research, 75% of the risk of colorectal cancer is now believed to be due to diet. About 86% of skin cancer risk is due to sun exposure while 75% of chance of developing head and neck cancers is because of tobacco and alcohol, researchers said.
Although some rare cancers can be driven by genetic mutations, the most prevalent diseases are down to environmental factors, researchers said, adding that it is important that these `extrinsic’ factors are taken into account in cancer prevention.
Source: Times of India 18 Dec’2015