Obesity and cancer: Shedding light on a growing health concern

Beyond obesity's association with cardiovascular diseases and metabolic disorders, mounting evidence reveals a deep-rooted connection between obesity and cancer risk.

Although cancer has long been understood as a complex and multifaceted disease, recent research has unveiled obesity as a significant modifiable risk factor. Per CDC estimates, there is convincing evidence that obesity is associated with an increased risk for at least 13 cancers. After smoking, unhealthy weight is considered the No. 1 modifiable risk factor for cancer avoidance. It is estimated that out of new cancers detected in individuals aged older than 30 years, nearly 5% in men and 10% in women are related to unhealthy weight.

The common cancers caused by obesity include cancers of the GI tract, such as the esophagus, stomach, pancreas, gall bladder, liver, colon and rectum. It is also associated with a higher risk for postmenopausal breast, uterine, ovarian, thyroid and kidney cancer. Unhealthy weight poses an additional risk for converting patients with underlying blood disorders to multiple myeloma and a higher risk for meningioma-cancer of the brain lining.

The underlying cellular mechanisms that lead to cancer and obesity are similar. They primarily include:

• insulin resistance;
• chronic systemic inflammation; and
• other hormonal imbalances spurred by unhealthy weight.

Additional contributing factors include oxidative stress, disruption of circadian rhythms, altered gut microbiome and excess intake of ultraprocessed foods.

Obesity can significantly impact the prognosis of cancer because it is associated with a higher risk for cancer recurrence and reduced overall survival rates. Maintaining a healthy weight has a preventive role. Intentional weight loss of more than 5% of body weight has been associated with a lower risk for obesity-related cancers. It also increases your chances of a better response and outcome from cancer treatment modalities, relapse and recurrence. Studies have shown that bariatric surgery for weight management among women with obesity is associated with reduced overall risk for cancer. Similarly, obesity adversely affects cancer survivorship, impacting the quality of life, cancer progression and risk for new cancers.

When addressing the risk for cancer in patients with obesity, clinicians should adopt a proactive and personalized approach. It always starts with educating the patient and for them to understand that although cancer has many risk factors, managing one’s weight effectively is an essential step in keeping that risk minimal. Moreover, the strategies for weight management also help decrease one’s risk for obesity. Eating a diet centered around “real foods,” including protein and lots of fiber from nonstarchy vegetables, eliminating ultraprocessed foods, avoiding sugary drinks and managing stress and sleep, are all important.

By understanding the underlying mechanisms linking these two health challenges, we can empower individuals to take charge of their well-being and adopt lifestyle changes that promote weight management and overall health. Health care professionals should approach patients empathetically and provide the necessary tools and support to combat obesity and reduce their cancer risk. By empowering patients and working closely with them, we can pave the way for a future where the burden of cancer is lightened.

For more information on the relationship between obesity and cancer risk, the Obesity Medicine Association’s clinical practice statement on cancer and obesity can serve as a great resource.

References:

• Lazarus E, Bays HE. Obesity Pillars. 2022;doi:10.1016/j.obpill.2022.100026.
• Obesity and cancer. https://www.cdc.gov/cancer/obesity/index.htm. Accessed Aug. 16, 2023.