Several studies at this year’s congress explore the ever-growing evidence base on obesity and cancer. Three of our highlights are below.
Higher BMI, body fat, and larger waist and hips pose similar risk for 10 common cancers (Presentation TS02.03 – Monday 11 May)
Obesity increases the risk of developing 10 of the most common cancers, regardless of how it is measured, according to a study of more than 400,000 adults in the UK, presented at this year’s ECO. With central fatness (larger waist and hips) and general obesity (body mass index [BMI] and body fat percentage) associated with similar estimates of cancer risk.
The results suggest that BMI is an adequate measure of cancer risk from excess weight, and there is no advantage in using more complicated or expensive measures such as waist circumference or body fat percentage.
The researchers found that all six obesity measures they studied were positively and similarly associated with higher risk for 10 cancers. For example, each 4.2 kg/m2 (men) and 5.1 kg/m2 (women) increase in BMI above 25 kg/m2 (defined as being overweight) was linked with higher risk of cancers of the stomach (35% increase), gallbladder (33%), liver (27%), kidney (26%), pancreas (12%), bladder (9%), colorectal (10%), endometrial (73%), uterine (68%), postmenopausal breast (8%), and overall (3%) cancer.
Based on the results, the researchers estimate that if these associations were causal, being overweight or obese could be responsible for around 40% of endometrial and uterine cancers and 29% of gallbladder cancers; and could account for 64%, 46%, and 40% of deaths from these cancers respectively (see figure 8 of full paper, link below).
“We observed a linear association – the more severe obesity is, the higher the risk of developing and dying from these cancers, except for postmenopausal breast cancer”, say the authors who include Dr Carlos Celis-Morales and Solange Parra Soto from the University of Glasgow, UK. “But there was a lot of variation in the effects of obesity on different cancers. This tell us that obesity must affect cancer risk through a different number of processes, depending on the cancer type.”
Contact the author team: Dr Carlos Celis-Morales, University of Glasgow, UK E) [email protected]
Note the study has been recently published in the journal BMC Medicine. For full paper click here
Higher BMI in childhood may help protect women against breast cancer in later life, both before and after the menopause (Presentation TS02.04 – Monday 11 May)
A study of more than 173,000 women in Denmark, presented at this year’s ECO suggests that girls with a higher body mass index (BMI) during childhood are less likely than their peers with a lower BMI to develop breast cancer as adults, both before and after the menopause.
The findings contrast with those for adult BMI, which indicate that women who gain weight after menopause have an increased risk of postmenopausal breast cancer. While the authors are unsure why children with a higher BMI appear to be protected against breast cancer, they caution that having overweight or obesity can have many adverse impacts on general health.
“Our results suggest that having a higher BMI during childhood may lower your risk of breast cancer both before and after the menopause. But we must be really clear that weight gain should not be considered as a way of preventing breast cancer”, says lead author Dr Dorthe Pedersen from Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark. “There are so many health risks linked with having overweight or obesity, it is vital for women to maintain a healthy weight throughout their lives.”
The analyses suggest “inverse associations” between childhood BMI and breast cancer risk before and after the menopause, which means that breast cancer risks decreased as BMI increased. For example, when comparing two 7 year-old girls with an average height and one z-score difference in BMI (equivalent to 2.4 kg), the girl with the highest BMI had a 7% lower risk of developing pre-menopausal breast cancer and a 10% lower risk of developing post-menopausal breast cancer than the girl with the lower BMI.
Contact the author team: Dr Dorthe Pedersen, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark, E) [email protected]
For full abstract click here
For full poster click here
Research shows for the first time that protein complexes ‘inflammasomes’ are linked to obesity-related colon cancer (late breaker poster 0400)
New research presented at this year’s ECO (held online, 10-13 May) finds evidence that structures called inflammasomes (a part of the innate immune system that helps to regulate inflammation) could play an important role in the development of obesity-associated colon cancer. The study is by Dr Victoria Catalán and Professor Gema Frühbeck, University Hospital Navarra and CIBEROBN, Instituto de Salud Carlos III, Pamplona, Spain, and colleagues.
Inflammasomes form part of the innate immune system which provides the first line of defence against pathogens using a wide range of physical, chemical, and biological responses.
The study revealed for the first time that obesity and colon cancer increase gene expression levels of the proteins NLRP3, NLRP6, ASC, IL1B and NOD2 in VAT. Gene expression levels of adiponectin were also reduced in visceral adipose tissue in obese subjects as well as those with colon cancer. This may increase the risk of developing conditions such as type 2 diabetes and metabolic syndrome due to adiponectin’s role in modulating metabolic processes and improving insulin sensitivity. Conversely, colon cancer was associated with reduced expression of NLRP6 and IL18 in tissue samples taken from the colon.
The team also found evidence of a possible role for inflammasomes in altering the expression levels of proteins involved in maintaining the integrity of the intestinal wall.
The authors conclude: “These findings provide evidence about the potential involvement of inflammasomes in obesity-associated colon cancer by regulating inflammation and the intestinal-barrier integrity”.
They add: “Therefore, strategies to restore the functions of immunosurveillance of inflammasome components could represent an interesting target to identify and treat patients with obesity at increased risk for colon cancer development.”
Contact the author team: Victoria Catalán, Metabolic Research Laboratory, Clínica Universidad de Navarra, Pamplona, Spain E) [email protected]
For full abstract, click here