Author: Patricia Bohmann

Why is this study important?

Over 40% of people worldwide have abdominal obesity, characterized by excess fat around the waist (1), and nearly 30% are insufficiently physically active (2). This is concerning because both abdominal obesity and physical inactivity are established risk factors for cancer, yet they remain alarmingly common globally (3-5).This study is distinct in its focus on waist circumference as a measure of abdominal obesity, as opposed to the more commonly used body mass index (BMI), which reflects general obesity. Waist circumference is considered a more precise indicator of cancer risk because it is strongly linked to biological processes, such as insulin resistance, that play a key role in cancer development (6). By investigating how physical activity may reduce cancer risk in people with abdominal obesity – and how abdominal obesity influences cancer risk in physically active individuals – this research fills a critical knowledge gap and aims to inform more targeted public health strategies.

How did the study go about this?

The study followed 315,457 cancer-free participants from the UK Biobank study between 2006 and 2010 with a median follow-up period of 11 years. Participants were classified into four groups based on World Health Organization recommendations for waist circumference (>88cm for women and >102cm for men) (7) and sufficient physical activity (>150 minutes of moderate-to-vigorous physical activity per week) (8): 

(1) Abdominal leanness and sufficient physical activity

(2) Abdominal leanness and insufficient physical activity

(3) Abdominal obesity and sufficient physical activity

(4) Abdominal obesity and insufficient physical activity

Cancer diagnoses were identified through health records during follow-up. The analysis adjusted for factors such as age, sex, diet, smoking, and alcohol consumption to examine the relationship between abdominal obesity, physical activity, and cancer risk. Rigorous statistical methods ensured that the findings were robust and reliable.

What did the study find?

Our study produced several key findings:

(1) Abdominal obesity alone was associated with an 11% increased cancer risk and insufficient physical activity alone was related to a 5% increase in risk, compared to individuals with abdominal leanness and sufficient physical activity.

(2) Compared with people with abdominal leanness and sufficient physical activity, total (all) cancer risks for the other groups were as follows: 

• 4% increased risk for individuals with abdominal leanness and insufficient physical activity
• 11% increased risk for individuals with abdominal obesity and sufficient physical activity 
• 15% increased risk for individuals with both abdominal obesity and insufficient physical activity

(3) When focusing on abdominal obesity and physical inactivity related cancers, risks were as follows: 

• 8% increased risk for individuals with abdominal leanness and insufficient physical activity 
• 38% increased risk for individuals with abdominal obesity and sufficient physical activity 
• 48% increased risk for individuals with both abdominal obesity and insufficient physical activity 

(4) Combined, abdominal obesity and insufficient physical activity accounted for 2% of all cancers and 6% of obesity- and inactivity-related cancers within the UK Biobank cohort. These findings underscore the importance of maintaining a lean waist and engaging in physical activity to reduce cancer risk.

What are the key take-home points?

Our study reinforces the importance of adhering to public health recommendations: maintaining a lean waistline and engaging in regular physical activity are effective strategies for reducing cancer risk. When following both guidelines is not feasible, prioritizing the management of abdominal obesity may be particularly impactful. However, achieving the WHO guidelines requires more than individual effort. Systemic changes at the political and societal levels are essential to enable environments that support healthy behaviors. This includes multifaceted policy interventions, urban planning that encourages active lifestyles, and embedding public awareness campaigns about healthy living within educational systems. 

References

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2. Guthold R, Stevens GA, Riley LM, Bull FC. Worldwide trends in insufficient physical activity from 2001 to 2016: a pooled analysis of 358 population-based surveys with 1·9 million participants. The Lancet Global Health. 2018;6(10):e1077-e1086. doi:10.1016/S2214-109X(18)30357-7
3. Barberio AM, Alareeki A, Viner B, et al. Central body fatness is a stronger predictor of cancer risk than overall body size. Nat Commun. 2019;10(1):383. doi:10.1038/s41467-018-08159-w
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5. Moore SC, Lee IM, Weiderpass E, et al. Association of Leisure-Time Physical Activity With Risk of 26 Types of Cancer in 1.44 Million Adults. JAMA Intern Med. 2016;176(6):816-825. doi:10.1001/jamainternmed.2016.1548
6. Friedenreich CM, Ryder-Burbidge C, McNeil J. Physical activity, obesity and sedentary behavior in cancer etiology: epidemiologic evidence and biologic mechanisms. Mol Oncol. 2021;15(3):790-800. doi:10.1002/1878-0261.12772
7. World Health Organization. Waist circumference and waist-hip ratio : report of a WHO expert consultation, Geneva, 8-11 December 2008. Published online 2011. Accessed January 5, 2024. https://iris.who.int/handle/10665/44583
8. Bull FC, Al-Ansari SS, Biddle S, et al. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Br J Sports Med. 2020;54(24):1451-1462. doi:10.1136/bjsports-2020-102955