The study led by scientists from the London School of Hygiene and Tropical Medicine took place over the course of 7 years, following the health progress of the five million individuals through regular surveys, an unprecedented participant pool size. The team found that each 13-16 kg of extra weight on an average adult was linked clearly and linearly to a greater risk of six of the most common types of cancer.
Obesity is the largest health epidemic in the modern world and now the study shows that obesity is tied to higher risk of 10 of the most common cancers.
The study claims that obese and overweight individuals in the UK alone are contributing up to 12,000 cases of cancer per year, although it is hard to determine the exact numbers, as it is difficult to pinpoint obesity as the cause amid many other health concerns. Dr Krishnan Bhaskaran, lead researcher on the study, comments on the results, saying that “this variation tells us BMI must affect cancer risk through a number of different processes, depending on cancer type.”
Obesity was most closely linked to increased risk of uterus cancer but close behind were kidney, cervix and thyroid cancers. Those participants with high body mass index were also more likely to develop cancer of the liver, colon, ovaries and breast. "There was a lot of variation in the effect of BMI on different cancers," repeats Dr Bhaskaran. "For example, risk of cancer of the uterus increased substantially at higher body mass index and for other cancers we saw a more modest increase in risk or no effect at all."
Although it is difficult to correctly diagnose an obesity-triggered cancer, the study provides a strong case for the link between the two. "Although the relationship between cancer and obesity is complex, it is clear carrying excess weight increases your risk of developing cancer," says Tom Stansfeld from Cancer Research UK. "Keeping a healthy weight reduces cancer risk and the best way to do this is through eating a healthy, balanced diet and exercising regularly."
