What Role Does Being Overweight Play in Endometrial Cancer?

April 18, 2011

Endometrial cancer remains the most commonly diagnosed gynecologic cancer in the United States. In fact, the number of women affected by the disease continues to rise despite a slight decline in annual incidence rates in the past 30 years.

Endometrial cancer remains the most commonly diagnosed gynecologic cancer in the United States. In fact, the number of women affected by the disease continues to rise despite a slight decline in annual incidence rates in the past 30 years. Research has demonstrated a link between the development of the cancer and obesity and obesity lifestyles. To better understand this link and the potential for preventive interventions, Yale University researchers conducted a population-based case-control study of 668 women who received a recent diagnosis of primary endometrial cancer and 674 control participants.

Cases and controls were matched by age (in groups between 35 and 80 years old) and had similar demographic profiles, including place of birth, mother’s age at their birth, number of siblings, number of sisters, number of elder siblings, birth weight, and adult height. However, the control group had somewhat more Caucasian women and more women with increased years of education than the case group. Reported current weight and current Body Mass Index (BMI) was higher in cases than controls.

To assess changes over time, participants were asked to recall their height and weight at each decade during their adult lives. While BMIs increased for all participants regardless of disease status, BMI values were consistently higher in the case group as compared to the control group across the lifespan. Furthermore, the BMI increases over time were not parallel; the case group reported greater increases than the control group.

The researchers found an increased risk for endometrial cancer for those women with higher BMIs. Specifically, women with BMIs between 25 and 30 at time of the interview or 5 years prior had a 50% increased risk as compared to women with BMIs less than 25 at the same time; this was evident after adjusting for confounding and other risk factors. Obese women (BMI > 30) had a 4- to 5-fold increased risk. The researchers saw statistically significant increased risks (but lower odds ratios) when the BMIs were assessed in the women’s 20s and 30s. 

The researchers further examined the data to determine the long-term effects of increased BMIs on endometrial cancer. They combined BMI assessments across each decade of adulthood from participants’ 20s through their 50s. Women who consistently had BMIs of 25 or higher throughout their adult life had a nearly 5-fold increase in risk for endometrial cancer as compared to those women whose BMIs were always less than 25 during the same time span. After adjusting for risk and confounding factors, the researchers found a dose-response relationship between length of time of obesity and risk of endometrial cancer: the longer the time being overweight, the higher the risk of endometrial cancer.

Furthermore, the researchers noted that patients who had substantial increases in BMI during early adult life tended to receive a diagnosis of cancer at a much younger age. Specifically, they noticed that patients who experienced 35% or more weight gain during their 20s were diagnosed 10 years younger than those with 5% or less weight change during the same period. The age gap in diagnosis diminished when the weight gain occurred later in life.

“This observation provides additional evidence in support of obesity or overweight playing a critical role in endometrial cancer,” the researchers concluded. “It suggests that as an important risk factor, early exposure to excessive body weight may shift the timeframe of carcinogenic process resulting in early development of the disease.”

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Reference

Lu L, Risch H, Irwin ML, et al. Long-term Overweight and Weight Gain in Early Adulthood in Association with Risk of Endometrial Cancer. Int J Cancer. 2011; Mar 8 epub.