Journal of Cancer Research and Immuno-Oncology
Open Access

Role of Obesity in Breast, Colorectal, and Endometrial Cancer

Geest Wagne^{* *}Correspondence: Geest Wagne, Department of Oncology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK, Email:

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Description

Obesity, a condition characterized by excessive body fat accumulation, has reached epidemic proportions globally. According to the World Health Organization (WHO), more than 650 million adults were classified as obese in 2016, and the numbers continue to rise. The health risks associated with obesity are well-documented, encompassing cardiovascular diseases, diabetes, and respiratory disorders. However, one of the more alarming links that has emerged in recent years is the association between obesity and cancer. Research indicates that obesity is a significant risk factor for various cancers, and understanding this connection is important for effective prevention and treatment strategies.

Limitations of Body Mass Index (BMI) in assessing obesity

Obesity is typically defined using the BMI, which is calculated by dividing a person’s weight in kilograms by their height in meters squared. A BMI of 25-29.9 is classified as overweight, while a BMI of 30 or higher is classified as obese. This classification system, though widely used, does not account for the distribution of fat in the body, nor does it distinguish between muscle mass and fat mass. Nonetheless, BMI remains a useful indicator for assessing population-level trends in obesity and related health risks.

The prevalence of obesity has dramatically increased over the past few decades, driven by lifestyle changes, including increased caloric intake, decreased physical activity, and changes in food consumption patterns. This trend is alarming because of the numerous health complications linked to obesity, including its role as a major risk factor for several types of cancer.

Link between obesity and cancer

Research consistently shows that obesity is associated with an increased risk of developing several cancers. These include, but are not limited to, cancers of the breast (postmenopausal), colon, endometrium (lining of the uterus), kidney, esophagus, liver, pancreas, and gallbladder. The mechanisms through which obesity increases cancer risk are complex and multifactorial, involving hormonal imbalances, chronic inflammation, and metabolic disturbances.

Specific cancers linked to obesity

While obesity increases the risk for several types of cancer, the strength of the association varies depending on the type of cancer. Below are some of the cancers most strongly linked to obesity.

Breast cancer (postmenopausal): Obesity is a well-established risk factor for postmenopausal breast cancer. The increased risk is largely due to elevated levels of circulating estrogen produced by adipose tissue after menopause. Estrogen promotes the growth of hormone-receptor-positive breast cancer cells. Studies have shown that women with higher BMI levels are at a significantly increased risk of developing breast cancer after menopause compared to women with normal BMI.

Colorectal cancer: Obesity is strongly associated with an increased risk of colorectal cancer. The underlying mechanisms include insulin resistance, chronic inflammation, and alterations in the gut microbiome. Obese individuals often have higher levels of insulin and IGF-1, which can promote the growth of cancer cells in the colon and rectum. Additionally, the proinflammatory state associated with obesity may contribute to the development of precancerous polyps and their progression to colorectal cancer.

Endometrial cancer: Endometrial cancer is one of the most common cancers in women, and obesity is a major risk factor for this disease. The increased risk is largely driven by elevated estrogen levels in obese women, especially after menopause. Higher levels of circulating estrogen, coupled with lower levels of progesterone, promote the proliferation of the endometrial lining, increasing the likelihood of cancerous changes.

Kidney cancer: Obesity is a significant risk factor for renal cell carcinoma, the most common type of kidney cancer. The exact mechanisms linking obesity to kidney cancer are not fully understood, but it is believed that metabolic disturbances, such as insulin resistance and hypertension, as well as chronic inflammation, play a role. Adipose tissue surrounding the kidneys may also create a local environment that promotes tumor growth.

Esophageal cancer: Obesity has been linked to two types of esophageal cancer adenocarcinoma and squamous cell carcinoma with the strongest correlation seen in esophageal adenocarcinoma.

Gastroesophageal Reflux Disease (GERD), a condition where stomach acid backs up into the esophagus. Chronic acid reflux can damage the lining of the esophagus, leading to a condition known as Barrett’s esophagus, which increases the risk of developing esophageal adenocarcinoma.