Sugary Diet May Up Lung Cancer Risk in Non-Smokers
50% higher risk seen in never-smokers with carb-heavy eating habits
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A diet loaded with sugary foods and beverages appeared to be an independent and profound risk factor for lung cancer in never-smokers (less than 100 cigarettes in a lifetime), those diagnosed with squamous cell carcinoma (SCC), and those with less than 12 years of education, a retrospective case-control study showed.
Study participants whose diet had the highest glycemic index (GI) had a 49% greater risk for developing lung cancer than their counterparts whose diet had the lowest GI, according to Xifeng Wu, MD, PhD, of The University of Texas MD Anderson Cancer Center in Houston and colleagues.
Highest GI diet participants also had a 92% higher risk of developing SCC, possibly due to the influence of elevated insulin-like growth factors (IGFs), the investigators reported in Cancer Epidemiology, Biomarkers & Prevention.
"Smoking is still the most important, and the most well-characterized risk factor for lung cancer but we also found that the association between GI and lung cancer risk was stronger in certain subgroups of our study population, in particular, individuals who never smoked," Wu told MedPage Today.
This study adds to previous reports suggesting an association between a high-GI diet and lung cancer risk but it adds that for never-smokers and for certain histology subtypes, dietary factors such as GI may play a more important role in lung cancer risk.
"These findings do not entirely surprise me as similar data has been published in other cancers," said Sai Yendamuri, MD, of Roswell Park Cancer Institute in Buffalo, N.Y.
Yendamuri, who was not affiliated with the study, added that, "When people think of lung cancer, they think of smoking alone as a modifiable lifestyle choice that can impact its incidence. This study shows that there may be others as well."
In the study, glycemic load and GI were assessed among 1,905 patients with newly diagnosed lung cancer (who had been treated with surgery only) recruited from MD Anderson and 2,413 healthy controls from a large physician group in Houston. All participants completed an in-person interview, as well as a modified version of the NCI Health Habits and History Questionnaire.
The investigators assessed associations between quintiles of GI and glycemic load and lung cancer risk and the modifying impact of various risk factors. The analysis was limited to non-Hispanic whites.
Wu and colleagues found a significant association between GI [5th versus 1st quintile OR 1.49; 95% CI 1.21-1.83; P<0.001] and lung cancer risk and GIac (5th versus 1st: OR 1.48; 95% CI 1.20-1.81; P=0.001) and lung cancer risk.
Among study participants with fewer than 12 years of education, those in the highest GI group were 77% more likely to develop lung cancer than those in the lowest GI group (5th versus 1st quintile OR 1.92; 95% CI 1.30-2.83). By comparison, participants with more than 12 years of education had an increased risk of 33% in (5th versus 1st OR=1.75; 95% CI 1.19-2.58).
The investigators noted that educational attainment is a proxy for socioeconomic status which has been linked to a diet high in simple sugars and less fiber, and smoking. "The associations between GI and lung cancer risk in individuals with less than 12 years of formal education may represent the joint impact of low diet quality and smoking on lung cancer risk," they wrote.
Smokers in the 5th quintile for GI had a 33% increased risk of lung cancer compared to smokers in the lowest quintile.
There were no significant associations between glycemic load and lung cancer risk in most patients, suggesting that it is carbohydrate quality rather than the quantity that impacts lung cancer risk, said Wu.
The retrospective case-control nature of this study subjected it to recall and reporting bias and confounding, noted the investigators, who also pointed out that information on history of diabetes, hypertension, and heart disease was not factored into the analysis.
"The results from this study suggest that, besides maintaining healthy lifestyles, such as avoiding tobacco, limiting alcohol consumption and being physically active, reducing the consumption of foods and beverages with high glycemic index may serve as a means to lower the risk of lung cancer," said Wu.
Primary care physicians in particular should continue to advise patients to increase the proportion of low glycemic foods in their diets, including dried beans and legumes, whole grains, and nonstarchy vegetables, said Yendamuri. What's more, this discussion should be part of a larger conversation about smoking cessation, decreased radon exposure, and in patients with significant smoking history, possible enrollment in a lung cancer screening program, he told MedPage Today.
Study participants whose diet had the highest glycemic index (GI) had a 49% greater risk for developing lung cancer than their counterparts whose diet had the lowest GI, according to Xifeng Wu, MD, PhD, of The University of Texas MD Anderson Cancer Center in Houston and colleagues.
"Smoking is still the most important, and the most well-characterized risk factor for lung cancer but we also found that the association between GI and lung cancer risk was stronger in certain subgroups of our study population, in particular, individuals who never smoked," Wu told MedPage Today.
This study adds to previous reports suggesting an association between a high-GI diet and lung cancer risk but it adds that for never-smokers and for certain histology subtypes, dietary factors such as GI may play a more important role in lung cancer risk.
"These findings do not entirely surprise me as similar data has been published in other cancers," said Sai Yendamuri, MD, of Roswell Park Cancer Institute in Buffalo, N.Y.
Yendamuri, who was not affiliated with the study, added that, "When people think of lung cancer, they think of smoking alone as a modifiable lifestyle choice that can impact its incidence. This study shows that there may be others as well."
The investigators assessed associations between quintiles of GI and glycemic load and lung cancer risk and the modifying impact of various risk factors. The analysis was limited to non-Hispanic whites.
Wu and colleagues found a significant association between GI [5th versus 1st quintile OR 1.49; 95% CI 1.21-1.83; P<0.001] and lung cancer risk and GIac (5th versus 1st: OR 1.48; 95% CI 1.20-1.81; P=0.001) and lung cancer risk.
Among study participants with fewer than 12 years of education, those in the highest GI group were 77% more likely to develop lung cancer than those in the lowest GI group (5th versus 1st quintile OR 1.92; 95% CI 1.30-2.83). By comparison, participants with more than 12 years of education had an increased risk of 33% in (5th versus 1st OR=1.75; 95% CI 1.19-2.58).
The investigators noted that educational attainment is a proxy for socioeconomic status which has been linked to a diet high in simple sugars and less fiber, and smoking. "The associations between GI and lung cancer risk in individuals with less than 12 years of formal education may represent the joint impact of low diet quality and smoking on lung cancer risk," they wrote.
There were no significant associations between glycemic load and lung cancer risk in most patients, suggesting that it is carbohydrate quality rather than the quantity that impacts lung cancer risk, said Wu.
The retrospective case-control nature of this study subjected it to recall and reporting bias and confounding, noted the investigators, who also pointed out that information on history of diabetes, hypertension, and heart disease was not factored into the analysis.
"The results from this study suggest that, besides maintaining healthy lifestyles, such as avoiding tobacco, limiting alcohol consumption and being physically active, reducing the consumption of foods and beverages with high glycemic index may serve as a means to lower the risk of lung cancer," said Wu.
Primary care physicians in particular should continue to advise patients to increase the proportion of low glycemic foods in their diets, including dried beans and legumes, whole grains, and nonstarchy vegetables, said Yendamuri. What's more, this discussion should be part of a larger conversation about smoking cessation, decreased radon exposure, and in patients with significant smoking history, possible enrollment in a lung cancer screening program, he told MedPage Today.
The study was funded by grants from the National Institutes of Health, the Cancer Prevention Research Institute of Texas, MD Anderson institutional support for the Center for Translational and Public Health Genomics, and the NCI R25T Postdoctoral Fellowship in Cancer Prevention.
No potential conflicts of interest were disclosed.
No potential conflicts of interest were disclosed.
last updated
Primary Source
Cancer Epidemiology, Biomarkers & Prevention
Source Reference: Wu X, et al "Glycemic index, glycemic load, and lung cancer risk in non-hispanic whites" Cancer Epidemiol Biomarkers Prev 2016; DOI: 10.1158/1055-9965.EPI-15-0765.
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