Does Obesity Cause Cancer? Here’s What New Research Says

Does Obesity Cause Cancer? This article covers everything you need to know about the link between obesity and cancer.

According to a 2011 review of numerous cohort studies, about 85,000 new cancer cases reported annually in the U.S. are attributed to obesity. Additionally, every 5 kg/m² increase in body mass index (BMI) raises cancer mortality by 10%. Some studies also reported reduced cancer incidence and mortality among candidates who had drastically lost excess weight.

Data from a 2017 Vital Signs report compiled by the CDC paints a similar picture. The report points out that cancers related to obesity make up 40% of all the cases diagnosed in the U.S. It goes on to show that being obese or overweight increases the risk of 13 types of cancer.

Such statistics are worrying given that, on average, 41.9% of the U.S. adult population (aged 20 years and over) is obese or overweight. But is there a direct link between obesity and cancer, and does being obese increase the risk of getting cancer? Researchers have been hard at work trying to validate such hypotheses. And so far, all evidence points to a strong and undeniable positive correlation between cancer and obesity.

Link Between Obesity and Cancer

On a side note, WHO defines “overweight” as a BMI equal to or greater than 25 kg/m² and “obesity” as a BMI equal to or greater than 30 kg/m². This distinction is not crucial in this context. So, the article will use both terms interchangeably to mean the same thing (abnormal or excessive bodyweight characterized by an over surplus of fat accumulation).

Being obese causes various changes in the body that can lead to cancer or foster carcinogenic factors. Excess body fat can increase the chances of neoplastic gene mutations, alter the functions of cell growth factors, and amplify chemical pathways that encourage abnormal neogenesis.

Here’s a more detailed look at the biological mechanisms behind the cancer-obesity relationship:

The Insulin Resistance Link

This is one of the most studied connections between cancer and obesity. Insulin is a peptide hormone the pancreas produces to regulate blood sugar levels. Studies show that overweight people develop insulin resistance, a condition where cells stop responding to insulin signals. Naturally, the pancreas responds by producing more insulin than normal. Consequently, high insulin levels in the body (hyperinsulinemia) can lead to a host of adverse health problems, including type 2 diabetes and cancer.

Hyperinsulinemia coupled with insulin resistance triggers complex insulin-like growth factor-1 (IGF-1) pathways that promote cell proliferation and suppress apoptosis. Such an environment motivates cancer development and growth. Insulin resistance is a well-established risk factor for endometrial, breast, colon, kidney, and pancreatic cancers.

The Endocrinal Link

Obesity, specifically excess adipose or fat tissue, alters the levels and functions of various hormones in the body that can lead to cancer formation or growth. Researchers have linked the following hormones to increased cancer risk in obese individuals:

• Sex Hormones

Excessive adipose tissue interferes with the mechanisms that regulate the production of sex hormones — androgens, estrogens, and progestogens. This causes a hormonal imbalance that can seed hormone-dependent malignancies such as breast, ovarian, uterine, and prostate cancers. For instance, excess estrogen readily binds to IGF, an action that promotes neoplasticism by inhibiting programmed cell death.

• Adipokines

Adipokines (adipocytokines) are cytokine hormones excreted by the adipose tissue. The most common adipokines are leptin, adiponectin, and ceruloplasmin. These play active roles in regulating appetite, glucose and lipid metabolism, fat distribution, and insulin sensitivity, which explains their high quantities in overweight people. Recent evidence suggests that excessive adipokines can trigger cancer development by encouraging cell proliferation and metastasis, anti-apoptosis pathways, gene mutations, and inflammation.

• Glucagon

Glucagon is produced by the pancreas’s alpha cells. It works alongside insulin in regulating the amount of sugar (glucose) in the blood. While insulin keeps the blood sugar from rising too high, glucagon prevents it from dropping too low. But due to insulin resistance, the restraining influence of insulin on glucagon production in obese individuals is minimal, causing excess glucagon secretion (hyperglucagonemia). Although research in this area is quite scarce, some studies show a strong connection between glucagon and various cancers.

The Chronic Inflammation Link

A 2017 study found that excess fat puts the body in a state of constant inflammation and oxidative stress. Chronic inflammation is a known risk factor for various health issues, including cardiovascular diseases, psoriasis, diabetes mellitus, insulin resistance, metabolic syndrome, and cancer. Inflammatory cells create an ideal microenvironment for rapid cell differentiation and migration, genetic mutations, and tumor growth.

The Fatty Acid Synthase (FAS) Link

Fatty acid synthase (FAS) is an enzymatic system composed of two multifunctional polypeptides. Its job is to catalyze the synthesis of palmitate (palmitic acid), a long-chain fatty acid made up of 16-carbon molecules. Among other functions, palmitate provides metabolic fuel to power cellular activities, growth, and health.

As a 2020 study points out, fatty acid metabolism is a critical pathway to cancer development. FAS action can provide the necessary energy for neoplasticism and metastasis. Additionally, mutations in the FASN gene, made plausible by the low-grade chronic inflammatory state in obese people, can rewire tumor cells to metabolize faster and meet their high energy demand for growth.

Does Obesity Cause Cancer? Final Word

Can obesity cause cancer? The simple answer is “yes.” Obesity is a leading risk factor for 13 different types of malignancies and is responsible for thousands of new cancer cases and fatalities yearly. Generally, the correlation between obesity and cancer is pretty straightforward: the heavier you are and the longer you stay overweight, the higher your chances of getting cancer.

Hundreds, if not thousands, of studies, have conclusively demonstrated the primary and secondary effects of obesity and the potential for developing various types of cancer.

At the very least, proven cancer risk strongly motivates overweight individuals to try and lose excess weight. The good news is that lifestyle changes, dieting, and physical exercise can go a long way toward achieving a healthy BMI. But for some, more aggressive measures such as gastrectomy, gastric bypass, liposuction, or medication may be necessary. The point is that obesity-related cancers are highly preventable and even treatable if proactive and corrective measures are taken promptly.

Get in touch with Brio-Medical to learn more about cancer risks, prevention, management, care, and treatment.

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