Tackling reduction at home

While much of Manchester’s innovative cancer research is directly responding to the needs of its diverse regional populations, it is also resulting in policy changes and cancer detection improvements in global populations. Professor Andrew Renehan talks about his home-focused cancer research programme, which is resulting in global benefits.

Globally, if populations had the same weight now as they did in 1982, we could avoid half a million new cancers annually. Obesity is the second most common cause of cancer in western populations. In some countries it is the most common cause of cancer in women ahead of smoking. In the UK, it’s the biggest cause of cancer after smoking.

In the past decade, we have led internationally-rated research that has contributed substantially to our understanding about the link between obesity and cancer incidence. This includes establishing obesity as the second most common cause of cancer in western populations and establishing a variety of biological mechanisms underpinning this. We have demonstrated that the effect of obesity on cancer takes place over many decades and, in many examples, may start in childhood.

We’ve also looked at the impact of a significant weight gain on 20 types of cancer. We found that a 15kg (2st 5lb) weight rise in women triggered up to a 50% increase in the risk of cancer in the oesophagus and a 30% increase in thyroid cancer risk. A 13kg (2st) weight gain in women would increase the risk of gall bladder and womb cancers by more than half. We also saw smaller but significant links between increases in weight and kidney, bowel and skin cancers in men, and kidney, pancreatic, thyroid, colon and some breast cancers in women.

Health inequalities and cancer

There are multiple factors which are contributing towards increasing obesity rates nationally and globally, including what is known as the ‘social gradient’ where obesity prevalence is higher in more socially deprived populations.

But the key challenges facing the cancer research community over the next decade are the same.

We need to increase public awareness of the proven link between obesity and cancer. We need to optimise the effectiveness of public health strategies and individual-level decision making around diet and exercise to minimise excess weight gain over adulthood. And we need to identify high-risk groups who we need to target this activity towards in order enhance the efficiency of these interventions.

Our research has also shown that increases in body weight during early adulthood increases risk of incident (newly-diagnosed) colorectal cancer in a gender-specific pattern, that increased waist circumstance is associated with increased risk of incident colorectal cancer in a gender-specific pattern, and that changes in body mass index over time in a population can be described in terms of ‘latent classes’ which differ by gender. All these observations point to the need for gender-specific and age-specific strategies to prevent obesity-related cancers.

As a clinician researcher, my work is divided 50:50 between research and clinical service. In my clinic I see the very real impact of obesity and as a researcher; I know the most powerful research response that we can provide to tackle the obesity epidemic is to build a critical mass of researchers. This research mass multiplies our research efforts and accelerates progress meaning that we can tackle this global problem at a much quicker pace, saving lives.

This is why one of our immediate three year challenges is to work out whether or not obesity after cancer diagnosis has an adverse effect on survival.  If true, this would be the fundamental rationale for intervening in cancer patients to ensure that they avoid excess weight gain or for us to encourage weight loss where there is excess body mass.

Professor Andrew Renehan

Professor of Cancer Studies and Surgery, The University of Manchester and Honorary Consultant Colorectal Surgeon and Christie Surgical Oncology Research theme, The Christie NHS Foundation Trust

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Global impact at home

The research we have undertaken in Manchester showing that a healthy weight can substantially reduce your risk of certain types of cancer, indeed of showing a clear link between obesity and cancer, has a global benefit. But we need to ensure that the knowledge developed in this city to help the growing number of obese children on our doorstep do benefit from this. While this is a global lesson, we can’t forget the need to apply our own lessons closer to home.

My hopes for the Manchester cancer research community over the next 12 months are that we continue building on increasing local public awareness of the link between obesity and cancer, something we’re now specifically targeting towards our own university students.

The time spent at university is a really intense learning period in a person’s life and a great opportunity to ‘soak up’ information. With the largest number of university students in the UK, and the largest international student population, there are immense opportunities here for us to develop a network of lifestyle ambassadors that can help in awareness-raising.

They can take the lessons we’ve learned in Manchester with them across the globe. They can ensure that Manchester helps not only its local communities but its wider global communities.