There is more to cancer than the genes

Experts say healthy body weight and lifestyle could keep cancer at bay

Are cancers essentially a disease of the genes and chance mutations? How far do lifestyle and environmental factors influence one’s lifetime risk of cancer?

A new study published in the January 2015 issue of the journal of Science by scientists at the Sidney Kimmel Cancer Centre at the Johns Hopkins University School of Medicine says that “only a third of the variation in cancer risk among tissues is attributable to environmental factors or inherited predispositions and that the majority is due to “bad luck,” that is random mutations arising during DNA replication in normal, non-cancerous stem cells.”

So if the majority of cancers are just pure bad luck, then is cancer prevention an unattainable goal?

Scientific bodies such as the World Health Organization and the World Cancer Research Foundation maintain that no more than 10 per cent of the cancers are due to inherited genes and that at least one-third of all cancers could be prevented by adopting healthy lifestyle choices and maintaining a healthy body weight throughout life.

Cancer is essentially a disease related to genes and its mutations but nutritional and environmental factors and lifestyle choices can play an important role in determining these gene mutations or even in changing the function of genes. One’s choice of food, levels of physical activity, habits like smoking or alcohol use, and body weight can still swing the balance in one’s favour when it comes to cancer, it is pointed out.

The link between obesity and cancer has been clearly established in a large study conducted by the International Agency for Research on Cancer, published in

The Lancet Oncology in November last year, which found that 3.6 per cent of the global cancer burden is linked with high body mass index (defined as BMI above 25). It said that the obesity-cancer risk was higher for women.

The overall message of the study was that “obesity is a certain and avoidable cause of cancer.”

“Cancer is a multi-factorial disease. All obese persons are not at risk of cancer but the mechanism of fat cells in the body — fat cells produce more oestrogen and other hormones and can stimulate affect tumour growth — has been clearly established.

Maintaining a healthy body weight and adequate physical activity is thus protective in many ways,” Aleyamma Mathew, who heads the Cancer Registry at the Regional Cancer Centre said.

(Reporting by C. Maya)