Overweight and obesity have long been established as contributing factors to various cancers, particularly those affecting the breast, bowel, and liver. However, recent research highlights that the location of body fat may be just as critical as the amount of fat when it comes to cancer risk.
A study published in the Journal of the National Cancer Institute investigates how fat distribution influences the risk of twelve obesity-related cancers. It was found that abdominal fat, commonly known as belly fat, is linked to an increased likelihood of three specific cancer types.
Researchers suggest that improving understanding of fat distribution can help identify individuals who may be at a heightened risk for developing cancer. Traditional measures such as Body Mass Index (BMI), previously used to assess obesity, may not capture the nuances of cancer risk adequately, prompting experts to explore alternative methodologies.
Fat Distribution and Cancer Risks
The study analyzed fat in five distinct areas of the body:
- Abdominal subcutaneous adipose tissue (belly fat)
- Visceral adipose tissue (fat surrounding internal organs)
- Gluteofemoral adipose tissue (fat in the buttocks and thighs)
- Liver fat
- Pancreas fat
The findings indicate that abdominal fat is linked to higher risks of endometrial, esophageal, and liver cancers. Conversely, fat located in the hips and thighs appears to lower the risk of breast cancer and meningioma, a type of brain tumor.
Daniel Landau, MD, an oncologist and hematologist not involved in the research, emphasized the significance of fat location, stating, “It seems that not only does obesity matter but obesity location matters.” He noted that central obesity is associated with severe health ramifications including diabetes and cancer, as it is believed to correlate with poor dietary habits and increased inflammation.
To analyze the causal effects of fat distribution patterns on cancer risk, researchers utilized a complex methodology known as two-sample Mendelian randomization. This methodology leverages genetic data to examine how fat distribution might relate to different cancer types. Data for the study was drawn from the UK Biobank and FinnGen.
Anton Bilchik, MD, PhD, a surgical oncologist who did not participate in the study, remarked on the ambitious approach, noting that the methodology is “extremely complex, using genetic tools to evaluate adiposity distribution, potential mechanisms, and the relationship to different obesity-related cancers.”
Unexpected Findings
Among the insights revealed, belly fat proved most influential in elevating the risk of three distinct malignancies. However, it also showed a potential protective effect against some types of breast cancer. In addition, both liver fat and visceral fat were found to increase the risk of liver cancer, while excess fat around the buttocks and thighs was linked to decreased risks of breast cancer and meningioma.
Bilchik expressed astonishment over the finding that higher levels of gluteofemoral fat might reduce breast cancer risk, suggesting that the cells in that area may have protective effects, possibly due to hormones like estrogen.
While there is a clear association between fat distribution and coronary health, the researchers concluded that the relationship is not as straightforward when it comes to cancer outcomes, noting varying causal effects depending on the type of cancer.
Landau echoed sentiments about BMI’s limitations, advising that healthcare professionals should look beyond this metric. He stated, “I think the other thing this study confirms is that BMI is not the best marker of health. I consider BMI to be ‘quick and dirty.’ It gives someone a very quick and basic idea of their health, but obesity location matters.”
Understanding the Mechanisms
According to the National Cancer Institute, several mechanisms may explain the increased cancer risk linked to excess weight:
- Adipose tissue produces estrogen, a hormone associated with several cancer types.
- Individuals with obesity tend to have elevated insulin levels, which are linked to multiple cancers.
- Chronic inflammation common in obesity can foster tumor growth.
- Fat cells generate hormone-like substances called adipokines that can stimulate cellular growth.
Weight loss has been shown to lower the risk of developing obesity-related cancers. A study involving nearly 60,000 post-menopausal women indicated that those who lost at least 5% of their body weight experienced a reduced risk of such cancers. Furthermore, a 2020 review underscored the need for additional research while promoting weight loss as a compelling cancer-prevention strategy.
