A report in the British Journal of Cancer (BJC) into risk factors and causes of cancer has featured heavily in the news (www.bbc.co.uk), with the headline grabbing figure coming from the report revealing that ‘40% of cancers are caused by lifestyle’.
For many cancers, adjustments in lifestyle might be expected to greatly reduce the risk of developing cancer. The most obvious example is lung cancer and cigarette smoking, but the association between obesity and alcohol consumption and breast cancer is also well-known.
But what about blood cancers?
There are however, some exceptions. It has been known for some time that there is a link between smoking and acute myeloid leukaemia (AML). The proportion of AML cases thought to be caused by smoking is significant - in some age groups it accounts for one in four cases. However, if you compare this with how many people are diagnosed with lung cancer each year as a result of smoking, the numbers of cases are relatively small.
Obesity may also be a risk factor, although there is no firm evidence in this area. A 2008 study revealed a moderate link between a high body mass index (BMI) and leukaemia, non-Hodgkin lymphoma and myeloma in both men and women.
So what does cause blood cancer?
This is a question which has concerned researchers for decades. Several risk factors, such as infection, have been linked to blood cancers. Perhaps the most established association is that between the Epstein-Barr virus and Hodgkin lymphoma, but bacterial infections are also known to cause stomach lymphoma and hepatitis C has been linked to other cases of non-Hodgkin lymphoma.
Occupational exposures to pesticides and chemicals have also been connected to increases in leukaemia, non-Hodgkin lymphoma and myeloma. However, in each case the increased risk was very slight and the number of attributable cases very small.
More work needs to be done to establish exactly how these devastating diseases can be triggered in otherwise healthy men and women. Leukaemia & Lymphoma Research are investing in research into why blood cancers develop but unfortunately it seems there will be no easy answer. The truth is most likely to lie in a combination of many different risk factors and triggers.
Henry – Science Communications team