The most common type of endometrial cancer occurred almost 80% more often in postmenopausal women who regularly consumed sugar-sweetened drinks as compared with women who consumed none, a large cohort study showed.
The prevalence of estrogen-dependent endometrial cancer increased steadily and significantly with self-reported weekly servings of sugar-sweetened drinks, boosting the hazard by 78% among women who consumed four or more servings a week.
The risk of the less common nonhormonal endometrial cancer was not significantly affected by consumption of sugar-sweetened drinks, Maki Inoue-Choi, PhD, of the University of Minnesota School of Public Health in Minneapolis, and co-authors concluded in an article published online in Cancer Epidemiology, Biomarkers & Prevention.
"We found that higher consumption of sugar-sweetened beverages was associated with higher risk of [estrogen-dependent) type I endometrial cancer, regardless of body mass index, physical activity, a history of diabetes, and cigarette smoking," the authors concluded. "Similarly higher risk of type I endometrial cancer was observed in relation to higher intake of sugars. The risk of [estrogen-independent] type II endometrial cancer was not associated with intake levels of sugar-sweetened beverages and sugars."
Consumption of sugar-containing drinks has risen in parallel to the prevalence of obesity in the U. S., offering one potential explanation for sugar's association with endometrial cancer, which occurs disproportionately in obese women.
In developed nations, obesity is associated with at least half of type I endometrial cancers. Epidemiologic studies have linked higher intake of sugar-sweetened drinks to higher risks of obesity and type 2 diabetes. Collectively, available evidence provides biologic plausibility for sugar-sweetened drink consumption as a contributing factor in endometrial cancer, the authors noted in their introduction.
The only previous study of sugar-sweetened drinks and endometrial cancer found no association. However, the study lacked data on specific levels of drink consumption. Additionally, endometrial cancer had not been classified into two distinct histologic subtypes at the time of the previous study.
To address limitations in the literature, Inoue-Maki -- currently a postdoctoral fellow at the National Cancer Institute -- and colleagues analyzed data from the Iowa Women's Health Study, a longitudinal cohort study involving women 55 to 69. At enrollment, each participant completed a detailed questionnaire about demographics, lifestyle factors, medical history, and dietary intake.
The food intake portion of the questionnaire included usual intake frequency for 127 food and drink items over the past 12 months. Possible responses ranged from "never or less than once per month" to "six or more per day."
The questionnaire included four items pertaining to consumption of sugar-sweetened beverages, including carbonated and noncarbonated drinks, fruit punch, lemonade, and noncarbonated fruit drinks. Participants completed 13 items related to consumption of "sweets and baked goods."
The final analysis included 23,039 women who had a mean age of 61.6 at enrollment. During follow-up from 1986 to 2010, 592 women had diagnoses of invasive endometrial cancer, consisting of 506 type 1 (endometroid) cancers and 89 type II (nonendometroid) cancers.
Factors associated with endometrial cancer were older age, higher BMI, higher waist-hip ratio, history of diabetes, early menarche, delayed menopause, any estrogen therapy. Smoking and increasing number of live births were associated with lower risk.
In an unadjusted analysis, increasing intake of sugar-sweetened drinks (excluding fruit juices) had a dose-dependent association with type I endometrial cancer (P=0.001). Women in the highest quintile of sugared beverage consumption had a 72% higher risk of type I endometrial cancer compared with women in the lowest quintile.
After adjustment for BMI, the resulting relative risk for comparison of the highest and lowest quintiles of consumption increased to 78% (95% CI 1.32-2.40, P=0.0005).
A separate analysis of fruit juice consumption yielded relative risks that were 38% and 48% higher in the unadjusted and adjusted models (95% CI 1.09-2.00, P=0.02 after adjustment).
Consumption of sugar-free drinks had no association with endometrial cancer risk, nor did consumption of sweets and baked goods. Analysis of different types of sugar showed a trend toward increased risk of endometrial cancer with increasing intake of sucrose and glucose.
The finding that sugar-sweetened drinks might contribute to the most common type of endometrial cancer is not particularly surprising, given the cancer's association with obesity, said Ronald Alvarez, MD, of the University of Alabama at Birmingham. Sugar in beverages might also affect insulin and insulin growth factor, which could play a role in type I endometrial cancers.
The lack of association between sugary foods and endometrial cancer is puzzling, he added.
"This is somewhat contradictory," Alvarez told MedPage Today in an email. "Is it the amount of sugar or the type of sugar that may differ between drinks and foods? I would say we need more information about that before we can explain this."
Primary source: Cancer Epidemiology, Biomarkers & Prevention
Source reference: Inoue-Choi, M et al "Sugar-sweetened beverage intake and the risk of type I and type II endometrial cancer among postmenopausal women" Cancer Epidemiol Biomarkers Prev 2013; DOI: 10.1158/1055-9965.EPI-13-0636.