Obesity May Raise Risk of Ten Common Cancers

Dr Krishnan Bhaskaran MSc PhD. Senior Lecturer in Statistical Epidemiology & National Institute for Health Research Postdoctoral Fellow London School of Hygiene and Tropical Medicine London WC1E 7HTMedicalResearch.com Interview with:
Dr Krishnan Bhaskaran MSc PhD.
Senior Lecturer in Statistical Epidemiology &
National Institute for Health Research Postdoctoral Fellow
London School of Hygiene and Tropical Medicine
London WC1E 7HT

Medical Research: What are the main findings of the study?

Dr. Bhaskaran: Body mass index was associated with the majority of cancer types studied, and for 10 cancers, including some of the most common like colon cancer and postmenopausal breast cancer, higher body mass index was clearly associated with higher risk.

The cancer type that was most strongly related to BMI was uterine cancer, the 4th most common cancer in women. For a woman of average height, each 2 stone (13kg) increase in weight increased risk by over 60%. Body mass index also had particularly large effects on risk of kidney and gallbladder cancers.

In total, we estimated that over 12,000 cases of the 10 affected cancers may be caused each year by excess weight, and that if average body mass index in the population continues to increase, there may be several thousand more cases of these cancers each year as a result.

Medical Research: Were any of the findings unexpected?

Dr. Bhaskaran: One thing that was striking was the range of effects that we saw for different cancers. For example, the risk of uterus cancer increased substantially at higher body mass index; for other cancers, we saw more modest increases in risk, or no effect at all. For some cancers like breast cancer occurring in younger women before the menopause, there even seemed to be a lower risk at higher BMI. This variation tells us that BMI must affect cancer risk through a number of different processes, depending on the cancer type.

Medical Research: What should clinicians and patients take away from your report?

Dr. Bhaskaran: For people who wish to lose weight, making realistic but permanent changes towards healthier food choices and more physical activity is likely to be the best long-term approach, and clinicians are in a unique position to encourage and support people in taking these steps. What this research shows is that in addition to the well-known effects in reducing the risks of cardiovascular disease and diabetes; maintaining a healthy weight can also help to minimise the risk of many common cancers.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Bhaskaran: This was a broad ranging study that looked at the big picture across many cancers. We saw lots of interesting nuances to the BMI-cancer relationships that could be investigated further on a cancer-specific basis. Just as important, we need good quality research and evidence on what steps can be taken at a policy level to help curb the increasing trends in BMI levels and excess weight, which we now know are responsible for many thousands of cases of cancer in the UK each year.

Citation:

Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5·24 million UK adults
Dr Krishnan Bhaskaran PhD,Ian Douglas PhD,Harriet Forbes MSc,Prof Isabel dos-Santos-Silva PhD,Prof David A Leon PhD,Prof Liam Smeeth PhD
The Lancet – 14 August 2014
DOI: 10.1016/S0140-6736(14)60892-8