Many reports in the recent literature have discussed the negative effect obesity has on many conditions, including cancer risk and survivorship. Study after study adds to the ammunition for a healthful diet and weight loss. Obesity rates among US adults more than doubled between 1970 and 2010, while childhood obesity rates have tripled in the last 30 years.1 According to the National Cancer Institute (NCI), these frightening trends could raise annual obesity-related medical costs to an estimated $66 billion by 2030.1
The medical community has done a good job of publicizing that obesity can lead to higher risks of diabetes, chronic heart disease (CHD), stroke, hypertension, and several other chronic diseases. However, the lay public is not as familiar with the connection between obesity and several types of cancer. Obesity is recently linked to colorectal, endometrial, esophageal, gallbladder, kidney, pancreatic, thyroid, cervical, ovarian, and postmenopausal breast cancers. Risk for cancer recurrence and mortality is greater in overweight or obese people as well.1
SPREADING THE WORD
In response to this trend, the University of Texas M.D. Anderson Cancer Center established the Center for Energy Balance in Cancer Prevention and Survivorship. The center defines energy balance as “… equalizing the amount of calories one takes in with how much one burns through exercise, metabolism, and body processes.”2 The objective of establishing the center is to bring a research-based multidisciplinary approach toward understanding the effect of obesity on cancer risk, consequences, and survivorship.
Karen Basen-Engquist, PhD, Professor of Behavioral Science and director of the new center, explains, “Obesity is a major risk factor for developing cancer, roughly the equivalent of tobacco use, and both are potentially reversible. Further, obese cancer patients do worse in surgery, with radiation or on chemotherapy—worse by any measure.”2
AREAS OF RESEARCH
In addition to its ongoing research, the Center for Energy Balance will also collaborate with other facilities to develop a foundation for basic and clinical research in these areas:
- The effect of exercise, nutrition, and weight control on outcomes in cancer survivors and people who have an increased risk of developing cancer,
- Dissemination and implementation research related to energy balance interventions, and
- Behavioral science research in exercise, eating behavior, and weight loss.
By establishing evidence-based changes in standards of clinical practice among all cancer institutions, the center’s staff hopes to advance policy initiatives aimed at reducing the risk of obesity-related cancer.
IMPACT ON CANCER
Using Surveillance Epidemiology and End Results (SEER) data, NCI estimates indicate that obesity was associated with approximately 34,000 new cases of cancer in men (4%) and 50,500 new cancer cases in women (7%) in the United States in 2007. The percentage of cases attributed to obesity varied widely for different types of cancer but some incidence rates were as high as 40%, such as endometrial cancer and esophageal adenocarcinoma. In its Obesity and Cancer Risk Fact Sheet, the NCI states that overweight and obese women of any menopausal status are 2 to 4 times more likely to develop endometrial cancer than are normal-weight women.1 These data also show that overweight and obese people are approximately twice as likely to develop esophageal adenocarcinoma as are people of healthy weight.1
Obesity impacts diagnostic procedures, patient prognosis, and therapy as well as incidence.
- Patients may not fit properly into imaging equipment, such as CT scanners.
- Obesity may confound diagnosis. Excess weight can obfuscate the appearance of tumors.
- Overweight can affect chemotherapy. Optimal dosing for obese patients is an area of clinical debate. Standard dose calculations based on total body surface do not allow for body composition. Miscalculating fat percentage may lead to suboptimum doses.
- Obesity promotes the development of secondary cancers, just as it encourages the growth of primary cancers.1
An analysis of the SEER data demonstrated that a 1% reduction in body mass index (BMI), which is equivalent to a weight loss of 2.2 pounds for an adult of average weight, could prevent an increase in the number of cancer cases. In addition, approximately 100,000 new cases of cancer could be avoided.1