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expert reaction to study on being overweight and survival of breast and colorectal cancer

Research, published in Cancer Epidemiology, Biomarkers & Prevention, reports that greater time spent being overweight lowers a patients chances of surviving breast and colorectal cancer. 


Dr Kathy Redfern, Lecturer in Human Nutrition, University of Plymouth, said:

“This study is one of the first to look at the amount of time spent overweight or obese in adulthood and cancer survival. However, the findings should be interpreted with caution as the cohort is relatively small, with small numbers of women predicted to experience overweight and dying from either cancer in the follow-up period.

“As the authors acknowledge, the study only looked at women, and just breast and colorectal cancer, so we cannot generalise these findings to say that ‘being overweight lowers your chance of surviving cancer after a diagnosis’ – as this could be misleading and potentially scary for those who may have recently received a cancer diagnosis. Further research in larger cohorts, to include men and those suffering from other cancers, is warranted.”


Julia Frater, Senior Specialist Cancer Information Nurse, Cancer Research UK, said:

“This study reinforces what we already know – that keeping and maintaining a healthy weight throughout one’s life can lower the risk of death from cancer and other diseases.

“It’s worth highlighting that the length of time someone was overweight for in their life made a big difference towards surviving their cancer. So, controlling what we can control, like making healthy lifestyle changes, is a good idea. That being said, the study only looked at women, and more research would need to be carried out to see if we see the same results in men and across more cancer types.”


Dr Duane Mellor, Senior Teaching Fellow, Aston Medical School, said:

“This study adds to the ongoing debate about the links between obesity and cancer, at a time where Cancer Research UK have been accused of stigmatising people of a higher body weight by using mocked cigarette packets with the word obesity on them. This research looked at a large group of women (47,000) with 1 in 300 developing cancer. Of the women who developed either breast or colon cancer, 1 in 8 were classified as being overweight. However, there are no details about if heavier women were more likely to develop either of these cancers in this study. Although those women who were overweight had a lower chance of surviving, this could be influenced by the fact that there was a much smaller proportion of overweight women in this study, so the numbers of overweight and healthy weight women were not anywhere being equal. Also, this study does not give us any information about the potential influence of weight in men who have survived colon cancer.

“This study does not offer anything particularly new, in that it does not explore the underpinning health behaviours and potential inequalities which increase the risk of a women being heavier and which are also associated with an increased risk of many cancers. Too often in studies like this weight is the target and there is no discussion of the role that the individual’s environment can have.

“This type of study is limited as it only presents a hazard ratio, and not the absolute change in risk associated with obesity on survival after these cancers. This way of presenting data can make the size of the effect look bigger than it might actually be.

“So, what does this mean in the real world? We need to make it easier to enjoy being healthy, by having tasty and healthy food accessible and acceptable to all and being able to be physically active as part of our daily lives. It is people’s behaviours which really impact the risk of surviving after cancer. Being both as healthy as possible throughout life is the best way of not only preventing many chronic diseases but also improving our chances of surviving them too.

“It is also important to remember that in people with cancer, sudden unexplained weight loss can be a bad sign, and perhaps we need to move away from a focus on weight to a focus on health – to being active to maintain muscle mass and eating healthily.”


Prof Justin Stebbing, NIHR Research Professor of Cancer Medicine and Medical Oncology, Imperial College London, said:

“The relationship between obesity and cancer is now becoming more and more apparent. This includes the fact that many new cases of cancer can be attributed to being overweight, at least in part. But, most studies have investigated obesity or body mass index at a single point in time. This interesting study in 47,000 people aged 20 to 50 years old from Sweden looks at this over time. It shows that a longer duration of being overweight is associated with an increased risk of dying in women with breast and colorectal cancer. In fact, every additional year of life lived with a BMI above 25 was associated with an increased risk and the scientists who wrote the paper use a term called ‘overweight intensity’, which summarizes the degree of overweightness over time. These findings point towards a long-lasting effect of overweight and obesity during young adulthood, impacting not only the risk to develop but also the chance of dying after a cancer diagnosis later on. These results need confirmation in other studies but adds to the growing evidence of an important relationship here, and is yet another reason to have a healthy lifestyle.”


* ‘Adult overweight and survival from breast and colorectal cancer in Swedish women’ by Melina Arnold et al. was published in Cancer Epidemiology, Biomarkers & Prevention at 00:01 UK time on Thursday 1st August. 

DOI: 10.1158/1055-9965.EPI-19-0075


Declared interests

Prof Justin Stebbing: No conflicts of interest.

Dr Duane Mellor: I am Nutrition Expert for Healthy For Men magazine (independently edited and managed for Holland and Barrett).  I have receive honoraria speaking for pharmaceutical companies in relation to nutritional management of cardiovascular disease and diabetes.

None others declared 

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