How Weight Increases Cancer Risk

February is Cancer Prevention Awareness Month. Here at the Abramson Cancer Center, we are committed to providing outstanding comprehensive cancer care and cancer information including ways to prevent cancer. Further, cancer researchers at Penn are at the forefront of learning new ways to prevent and detect cancer.

In this article, we discuss obesity, and how weight increases cancer risk, specifically, being obese. 

It’s no secret that more and more Americans are suffering from being overweight and obese. Perhaps it’s most evident in children, where it is estimated between 16 and 33 percent of adolescents are obese.

How Weight Increases Cancer Risk

Obesity is associated with increased risks of these types of cancers:

• Esophagus
• Breast (postmenopausal)
• Endometrium (the lining of the uterus)
• Colon and rectum
• Kidney
• Pancreas
• Thyroid
• Gallbladder

Also, obesity increases a person’s risk for heart disease, stroke high blood pressure, diabetes, and a number of other chronic diseases.

Several possible mechanisms have been suggested to explain the association of obesity with increased risk of certain cancers:

• Fat tissue produces excess amounts of estrogen, high levels of which have been associated with the risk of breast, endometrial, and some other cancers.
• Obese people often have increased levels of insulin, a condition known as hyperinsulinemia or insulin resistance, which may promote the development of certain tumors.
• Fat cells produce hormones, called adipokines that may stimulate or inhibit cell growth.
• Fat cells may also have direct and indirect effects on other tumor growth regulators.
• Obese people often have chronic low-level, or “subacute,” inflammation, which has been associated with increased cancer risk.

Other possible mechanisms include altered immune responses.

According to the National Cancer Institute:

A projection of the future health and economic burden of obesity in 2030 estimated that continuation of existing trends in obesity will lead to about 500,000 additional cases of cancer in the United States by 2030. This analysis also found that if every adult reduced their BMI by 1 percent, which would be equivalent to a weight loss of roughly 1 kg (or 2.2 lbs) for an adult of average weight, this would prevent the increase in the number of cancer cases and actually result in the avoidance of about 100,000 new cases of cancer.

Lose Weight to Lower Cancer Risk

Maintaining a healthy weight (a weight that falls within a BMI of 18.5-24.5) ranks at the top of the American Institute of Cancer Research’s recommendations for cancer prevention.

The National Weight Control Registry (NWCR) has been collecting data for more than a decade from people who have lost weight and have been able to maintain their weight loss.

They are sharing with us the top six trends that have come out of their surveillance. Nearly 90 percent of the members surveyed by NWCR reported they combined diet and exercise  to lose weight. So dig out your sneakers and get ready to move!

• Exercise. More than 50 percent of NWCR members reported expending 2000 calories a week. Check out AICR’s website for some suggestions of how you burn those calories too.
• Limit TV. Nearly two-thirds of NWCR members reported watching less than 10 hours of TV a week.
• Eat a low-calorie, low-fat diet. NWCR members maintain a similar diet 365 days a year Try filling half your plate with non-starchy fruits and vegetables that pack cancer fighting properties like spinach, broccoli, cucumbers, berries, grapes or melon.
• Eat breakfast. People surveyed said eating breakfast helped curb hunger and grouchiness as well as curb overeating later in the day
• Eat when hungry. Successful dieters from the NWCR maintained their weight loss by eating when they are hungry, not because the cake looked good or because they didn’t want to offend someone by not eating their dish. They also avoid the vending machine because when they are bored or stressed.
• Self monitor. And while you are looking for your sneakers, keep your eye out for your scale and smartphone. More than half of these successful dieters continue to weigh themselves weekly and keep a food journal. There are plenty of free websites and phone apps where you can log the calories you consumed and calories you burned each day.