Is Weight Gain Linked to Cancer Risk?

Excessive Weight Gain, Obesity, and Their Links to Cancer

While some have long speculated that being overweight or obese contributes to an increased risk of cancer, researchers only recently confirmed the link. The effects of weight on diabetes and cardiovascular disease are widely known, but a connection between weight and a diagnosis of cancer was not firmly established. A recent publication in JAMA: The Journal of the American Medical Association reviewed a report by the U.S. Centers for Disease Control and Prevention (CDC) that assessed more than 1000 studies - concluding that sufficient evidence exists to link weight gain, being overweight, and obesity with 13 different cancers.

Which Cancers Are Associated with Being Overweight or Obese?

The CDC’s report found that these 13 types of cancer are linked to being overweight or obese:

• Esophageal
• Gastric
• Colon and rectal
• Liver
• Gallbladder
• Pancreas
• Uterine
• Ovarian
• Kidney
• Thyroid
• Postmenopausal female breast cancer
• Meningioma (cancer of the membrane surrounding the brain and spine)
• Multiple myeloma (cancer of plasma cells)

The CDC studied the frequency of these 13 cancers in 2014 and the trends in these cancers over a 10-year period from 2005 to 2014. In 2014, more than 630,000 people were diagnosed with cancers associated with being overweight or obese. This included more than 55% of all cancers diagnosed among women and 24% of cancers among men. Most notable was the finding that cancers related to being overweight or obese were increasingly being diagnosed among younger people. From 2005 to 2014, there was a 1.4% annual increase in these cancers among individuals aged 20 to 49 years and a 0.4% increase among individuals aged 50 to 64 years. If cancer rates had stayed the same in 2014 as they were in 2005, there would have been 43,000 fewer cases of colorectal cancer but 33,000 more cases of other cancers related to weight gain. Nearly half of all cancers in people younger than 65 years were associated with being overweight or obese.

In addition to the CDC’s findings, an 18-year follow-up of almost 93,000 women in the Nurses’ Health Study revealed an association of weight gain and obesity with several cancers.

The Increasing Trend of Being Overweight or Obese

The prevalence of obesity in the United States has increased for almost 50 years. Currently, more than two-thirds of adults and almost one-third of children and adolescents are overweight or obese. Youth who are obese are more likely to be obese as adults, compounding their risk for health consequences like cardiovascular disease, diabetes, and cancer. Type 2 diabetes and coronary heart disease, both of which are linked to excess weight and obesity, also are on the rise.

Being overweight or obese as a young person may exact a toll on an individual’s health earlier in their lifetime. Given the time lag between exposure to cancer risk factors and cancer diagnosis, the high prevalence of overweight and obese adults and children in the United States may forecast even higher increases in the diagnosis of cancers that are related to weight gain.

What Can Be Done to Reverse the Trend?

Since the release of the landmark 1964 Surgeon General’s report on the health consequences of smoking, clinicians have told their patients to avoid tobacco, suggested methods to quit, and provided referrals to effective programs that reduce the risk of getting chronic diseases like cancer. These efforts, along with public health policies to reduce tobacco use, have been effective—cigarette smoking is at an all-time low. Similar efforts are warranted to prevent excessive weight gain and to recommend treatment for children, adolescents, and adults who are overweight or obese. These include:

• Behavioral Intervention Programs: Physician referrals to programs that help overweight and obese patients lose weight are an important starting point in improving their overall health and preventing diseases associated with excessive weight gain. The benefits of maintaining a healthy weight throughout life include a lessened risk of being diagnosed with some cancers.
• Screening: The U.S. Preventive Services Task Force (USPSTF) recommends that physicians screen for obesity and provide intensive behavioral interventions for children and adolescents who are obese. Measuring patients’ weight, height, and body mass index (BMI) over time, consistent with USPSTF recommendations, and counseling patients about maintaining a healthy weight can establish a foundation for preventive care.

Scientific data continue to emerge about the negative health effects of weight gain, including an increased risk of cancer. Even so, less than half of primary care physicians regularly assess the BMI of their patients. Encouraging discussions about weight management in health care settings, including physicians’ offices, clinics, emergency departments, and hospitals, provides an opportunity for patients to receive important information.

Challenges

Implementing clinical interventions including screening, counseling, and referrals, has major challenges. Since 2011, Medicare has covered behavioral counseling sessions for weight loss in primary care settings, but the benefit is not widely used. The reason remains unclear. Few medical schools and residency programs provide adequate training in prevention and management of obesity or in understanding how to make referrals to such services. Obesity is a highly stigmatized condition; many clinicians find it difficult to initiate a conversation about obesity with patients, and some may inadvertently use alienating language when they do. Studies indicate that patients with obesity prefer the use of terms such as unhealthy weight or increased BMI rather than overweight or obesity and improved nutrition and physical activity rather than diet and exercise. It is unknown if switching to these patient-friendly terms might lead to better outcomes.

Achieving sustainable weight loss requires that a physician helps a patient develop strategies supporting their efforts to make significant lifestyle changes. The availability of clinical and community programs and services is critically important. In addition to clinical services, linking community obesity prevention, weight management, and physical activity programs can connect people to valuable resources in the communities where they live, work, and play. Such programs provide the encouragement needed to make lifestyle changes that may significantly improve their health.

The high prevalence of excessive weight gain in the United States will continue to contribute to increases in health consequences related to obesity, including cancer. Nonetheless, cancer is not inevitable; it is possible that many cancers related to being overweight or obese can be prevented. Along with quitting or avoiding tobacco, achieving and maintaining a healthy weight also are key to reducing the risk of cancer.

For more information about weight loss, nutrition, and treatments for obesity, contact Matthew Brengman, MD, FACS at (804) 360-0600, or sign up for a free seminar about weight loss options (either online or in person).