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New study links risk of myeloma to obesity

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25 Aug 2016

Bloodwise reaction to news reports that myeloma risk is linked to being overweight.

It is known that being overweight can raise the risk of developing certain cancers, such as bowel, breast, kidney and oesophageal cancers. A study by the International Agency for Research on Cancer (IARC), part of the World Health Organization, has linked being overweight to an increased risk of developing eight more cancers, including the blood cancer myeloma.

The report, which is published today, is an interesting addition to our growing understanding of what causes different blood cancers, although there are some important points to consider.

IARC identified the link between myeloma and weight after carrying out an analysis of data from over 1,000 existing studies on excess weight and cancer, some of which focused on myeloma. The summary findings are published in The New England Journal of Medicine.

The researchers found that, on average, having a body mass index (BMI) of over 30 raises the relative risk of developing myeloma by 20% compared to a ‘healthy’ BMI (between 18.5 and 25). People with a BMI over 30 were also found to have an 80% increased risk of kidney cancer, liver cancer or stomach cancer.

It’s important to note that the overall risk of developing myeloma is still relatively low – a 20% increase raises the lifetime risk from just over 0.7% to just under 0.9%.

Dr Matt Kaiser, Head of Research at Bloodwise, said: “Being overweight has been linked to an increased risk of developing other types of cancer before, and this report looks at some of the recent data on myeloma.

This study found that for certain forms of cancer, the higher a person’s BMI, the greater their risk. What is less clear for some, like myeloma, is whether being overweight actually causes or contributes to myeloma, or whether other factors are responsible.

For myeloma, the report appears to mainly analyse population studies that track groups of people for a period of time, recording information about the participants and whether they develop myeloma. These indicate that excess body fat is associated with myeloma risk, but teasing out all the variables in these sorts of studies can be tricky.

Nevertheless, we encourage people to lead a healthy lifestyle, including eating a balanced diet and being physically active regularly, as even losing a small amount of weight can help reduce the risk of developing a range of diseases.

We are currently funding a couple of projects studying the role cholesterol plays in the transformation of the non-aggressive blood disorder MGUS into the more aggressive myeloma. This will provide information about a potential link between obesity and myeloma, which could be helpful for patients with MGUS, who are already at an increased risk of developing myeloma.”

The same study found only limited evidence that obesity was linked with another type of blood cancer – diffuse large B-cell lymphoma – the most common form of non-Hodgkin lymphoma. The study found no link between obesity and lung cancer or testicular cancer.  

The report published in The New England Journal of Medicine is an executive summary of a full report that is currently in preparation. We will be keeping a look out for the full analysis and update on any key details.

 

  • Body Fatness and Cancer — Viewpoint of the IARC Working Group. Lauby-Secretan, at al., for the International Agency for Research on Cancer Handbook Working Group. N Engl J Med 2016; 375:794-798, August 25, 2016, DOI: 10.1056/NEJMsr1606602