Obesity and Cancer: Weighing the Risks

In 2023, the US anticipates 1,958,310 new cancer cases and 609,820 deaths. This data underscores the urgency of understanding the contributing factors and risks associated with cancer.

Notably, obesity is a significant concern which links it to a heightened risk of 13 cancer types. Each year in the US, 40% of all diagnosed cancers fall into one of these types.

In this article, you will find out the intricate relationship between obesity and cancer, emphasizing its critical importance and the need for proactive measures.

Understanding Obesity

Obesity poses significant health risks to individuals. One of the most concerning risks is its strong link to various cancers.

Let's start by fully understanding what obesity means and the tools and measurements used to measure it.

Definition of Obesity

Obesity is a health condition caused by an excessive accumulation of body fat that potentially presents considerable health risks. This condition can lead to numerous health complications, including heart disease, diabetes, and certain types of cancer.

Body Mass Index (BMI)

The Body Mass Index (BMI) is a formula that relates a person's weight to height, typically used to measure obesity.

Body Mass Index is a value derived from height and weight. Below is the formula for BMI:

BMI = weight in pounds ÷ [height in inches]² x 703 [can be an image for easier formatting]

It’s an excellent screening tool to know where to classify the individual as underweight, normal, or overweight.

Criteria for Obesity

BMI is a universal measure for men and women of all ages and body types. Here's how to interpret the numbers and understand what they mean for your health.

• Underweight: Less than 18.5
• Normal weight: 18.5 to 24.9
• Overweight: 25 to 29.9
• Obesity (Class I): 30 to 34.9
• Severe Obesity (Class II): 35 to 34.9
• Morbid or Extreme Obesity (Class III): 40 and above

Those who are overweight and highly obese are at a greater risk of developing multiple types of cancer. However, this may still vary depending on the type of cancer and other factors (genetics, lifestyle, etc.) Still, in many cases, the risk increases with higher BMI.

While BMI is a useful starting point, a high BMI doesn't necessarily mean someone will develop cancer. It's best to consult healthcare professionals for a more in-depth evaluation of one's health regarding body fat and its associated risks.

Cancers Linked to Obesity

Between 2005 and 2014 in the US, new cancer cases related to overweight and obesity increased by 7%, except for colorectal cancer, which saw a 23% decrease. Meanwhile, cancers unrelated to overweight and obesity decreased by 13%.

To know which cancers are associated with obesity, refer to the list below:

• Breast cancer
• Endometrial cancer
• Ovarian cancer
• Colon and rectal cancer
• Esophageal cancer
• Upper stomach cancer
• Pancreatic cancer
• Liver cancer
• Gallbladder cancer
• Thyroid cancer
• Kidney cancer
• Meningioma (a type of brain cancer)
• Multiple myeloma

Obesity's Impact on Cancer Screening and Prevention

While obesity increases the risk of several cancer types, it can also negatively affect cancer prevention efforts, particularly when it comes to screening. Research has shown that obese women are less likely to participate in cervical cancer screening compared to women of normal weight. This disparity in screening rates is concerning, as regular screening is crucial for early detection and prevention of cervical cancer.

A systematic review and meta-analysis found that the likelihood of adhering to cervical cancer screening recommendations decreases with increasing obesity class. Women with class III obesity (BMI ≥ 40) were significantly less likely to participate in screening compared to women of normal weight. This reduced participation in cancer screening among obese individuals may contribute to delayed diagnoses and poorer outcomes.

Several factors may contribute to lower screening rates among obese women, including embarrassment, negative healthcare provider attitudes, inadequate equipment, and unsolicited weight-loss advice during medical visits. To improve cancer prevention efforts, it's essential to address these barriers and ensure that obesity does not hinder access to potentially life-saving screening procedures.

The Connection Between Obesity and Cancer

Extra body fat can raise the risk of cancer-related morbidity by about 17%. While we don't fully understand why, being obese affects how our body processes fats, balances hormones, and handles inflammation.

Obesity can trigger specific bodily shifts, including long-lasting inflammation, high insulin levels, insulin-like growth factors, and specific sex hormones. These changes may lead to the development of cancer. The more weight the person gains and keeps, the higher the cancer risk.

Considering this, there are factors that link obesity and the development of cancer. Below are these key factors:

1. Excess Amount of Estrogen

Obesity increases the risk of ovarian, endometrial, and menopausal breast cancer. Estrogen, known to stimulate rapid cell division in breast tissue, enhances the risk of mutations that can lead to the following types of cancer:

Obesity and Breast Cancer

Research shows that breast cancer and obesity are linked as overweight women have a higher chance of invasive breast cancer than those of normal weight. This is because of prolonged exposure to estrogen, a hormone prevalent in overweight individuals.

Obesity and Ovarian Cancer

After menopause, the ovaries stop producing hormones, and fat tissue becomes the main source of estrogen instead of the ovaries. Women who enter menopause after age 55 have a higher risk due to longer estrogen exposure during their menstrual cycles. This can lead to developing uterine, ovarian, and breast cancer.

2. Increased Leptin Production

Obesity can increase cancer risk through the following changes:

• Stomach infections
• Gut bacteria balance
• Lifestyle factors
• Metabolism issues
• Inflammation
• Certain substances produced by fat cells

Notably, increased levels of a substance called leptin have been linked to the development of cancer, specifically esophageal and pancreatic cancer, with studies showing it can make cells behave more aggressively. Lab studies also show that leptin increases harmful actions in cells.

Leptin is also known as the "satiety hormone," made by fat cells. In obesity, the body can ignore leptin's fullness signals, as the body becomes "leptin-resistant,” leading to overeating.

3. Increased Insulin and Insulin-Like Growth Factor 1 Levels

Being overweight raises the chance of cancer in both genders. Excess fat leads to higher insulin and Insulin-like growth factor 1 (IGF-1) hormone levels, which can stimulate the growth of the following:

• Kidney cancer
• Esophageal cancer
• Stomach cancer
• Pancreatic cancer
• Gallbladder cancer
• Upper stomach cancers

When altered by conditions like obesity, IGF-1 can fuel cancer growth by preventing cell death and boosting cell multiplication.

4. Chronic Inflammation and Oxidative Stress

When a person has obesity, their fat cells have to handle too much stored fat. This overloading results in these cells becoming stressed, leading to chronic inflammatory conditions, such as the following:

• Type 2 diabetes
• Metabolic syndrome
• Non-alcoholic fatty liver disease

As a response, certain messengers in the body get activated, which releases inflammatory chemicals that trigger a condition known as oxidative stress.

Oxidative stress can harm our cells and alter the genes. These changes and damages can pave the way for cancer. It can impact how the cells in the body function, either directly or by interfering with the body's antioxidant defenses.

Preventing Obesity-Linked Cancer

As obesity rates rise and its link to cancer becomes clearer, taking steps to prevent and lower the risk is vital. Here's how to lower your risk against obesity-related cancers:

1. Maintaining a Healthy Weight

Keeping your weight healthy is crucial for lowering the risk of various types of cancer. A balanced weight improves metabolic health, increases lifespan, and decreases the likelihood of chronic diseases. Losing even a small amount of weight can make a significant difference in reducing cancer risk.

Regular physical activity is a good way to maintain a healthy weight. Try to aim for at least 150 minutes of moderate exercise per week.

2. Eat a Healthy Diet

A diet rich in fruits, vegetables, lean meats, and whole grains can help you manage your weight and lower cancer risk. Here’s an example of a diet plan:

Breakfast:

• Scrambled eggs with spinach
• Whole-grain toast
• A small bowl of mixed berries

Lunch:

• Grilled chicken or tofu salad
• Mixed greens with cherry tomatoes and vinaigrette dressing
• Quinoa or brown rice

Dinner:

• Baked salmon or plant-based protein
• Steamed broccoli and carrots
• Mashed sweet potatoes or cauliflower

Snacks:

• Greek yogurt with honey and nuts
• Handful of unsalted nuts

You should also minimize intake of processed foods, red meat, alcohol, and sugary beverages.

3. Medical Supervision and Counseling

Healthcare professionals can provide personalized, research-backed guidance on achieving and maintaining a healthy weight. This tailored advice is really important, especially for people with difficulty following a weight loss plan or other health issues.

They can also monitor important health numbers like blood sugar, cholesterol, and hormones, which can change because of your weight and affect your risk of cancer.

The Bottom Line

The connection between obesity and cancer is complicated, influenced by factors like elevated hormone levels, chronic inflammation, and oxidative stress. Each of these can set the stage for cancer development.

Medical guidance is important for those with underlying health issues, as regular monitoring can catch risk factors early. By taking these steps, you can effectively mitigate your cancer risk.

FAQs on Obesity and Cancer

Why does obesity shorten life expectancy?

Obesity shortens life expectancy due to its association with a higher risk of health issues, such as heart disease, type 2 diabetes, and certain cancers. Depending on the severity, obesity can reduce life expectancy by an estimated 5–20 years.

Is chemo harder on obese patients?

Yes, studies suggest that obesity can make chemotherapy less effective. Fat cells may absorb the chemo drugs, making them less available to target tumor cells. This is particularly noted in breast cancer, where obese survivors show lower treatment efficacy. However, further research is needed to understand and improve these outcomes.

Can cancer be cured by weight loss?

Although increasing evidence suggests that reducing weight may decrease the likelihood of certain cancers, there is no scientific evidence that any special diet or weight loss can cure cancer.

What is the connection between obesity and prostate cancer?

The connection between obesity and prostate cancer risk is uncertain. Some studies indicate that obese men might have a lower risk overall, but they could be more prone to aggressive forms of prostate cancer.

What is the relationship between obesity and pancreatic cancer?

Obesity raises the risk of pancreatic cancer, likely due to factors like inflammation, insulin resistance, and changes in the gut bacteria.

Is there a connection between obesity and lung cancer?

Although lung cancer is not one of the 13 common types of cancer associated with obesity, lung cancer shows a connection to body weight. But instead of raising the risk of getting cancer, high BMI is associated with reduced lung cancer risk and better outcomes. However, this can vary by several factors, like age, gender, race, and BMI.

What is the biggest cause of cancer?

There is no single cause for cancer. It depends on different factors like genetics, lifestyle, and environment.

But for preventable cancers, the number one cause is cigarette smoking and secondhand smoke exposure, which are linked to lung cancer.

What's the importance of understanding the link between obesity and cancer?

Understanding the link between obesity and cancer is important because it helps you become aware of the risks and encourages you to take preventive measures. It also helps motivate individuals to make healthier lifestyle choices.

Does obesity affect cancer survival rates?

Yes, obesity can negatively affect cancer survival rates. There is a significant link between obesity and cancer, as excess body fat can interfere with the effectiveness of cancer treatments. This can result in poorer outcomes, including a higher risk of recurrence and lower overall survival.