Lung Cancer Risk Linked to Diets That Raise Blood Glucose and Insulin, Especially for Non-smokers

Lung Cancer Risk Linked to Diets That Raise Blood Glucose and Insulin, Especially for Non-smokers

A study from the University of Texas MD Anderson Cancer Center suggested that diets with a high glycemic index — affecting blood glucose and insulin levels — increased the risk of lung cancer in non-Hispanic whites, especially among non-smokers. The article, “Glycemic Index, Glycemic Load, and Lung Cancer Risk in Non-Hispanic Whites,” was published in the Cancer Epidemiology, Biomarkers & Prevention journal.

The American Cancer Society classified lung cancer as the second common cancer affecting both men and women. Its development is primarily associated with tobacco smoking.

Researchers aimed to identify the most likely factor contributing to lung cancer in people who never smoked or those with a cancer subtype called squamous cell carcinoma (SCC). The researchers proposed that a diet with an elevated  glycemic index (GI), a parameter measuring a rapid increase in blood sugar levels upon consumption of particular foods, could be a risk for developing lung cancer.

“Diets high in glycemic index result in higher levels of blood glucose and insulin, which promote perturbations in the insulin-like growth factors (IGFs),” Stephanie Melkonian, a postdoctoral fellow and lead author of the study, said in a news release. “Previous research suggests increased levels of IGFs are associated with increased lung cancer risk. However, the association between glycemic index and lung cancer risk was unclear.”

The study included data from 1,905 patients newly diagnosed with lung cancer and 2,413 healthy controls. Participants were asked for details about their health histories and dietary habits, and patients were divided into groups based on their GI and glycemic load (GL) indexes.

“We observed a 49 percent increased risk of lung cancer among subjects with the highest daily GI compared to those with the lowest daily GI,” said Professor Xifen Wu, MD, PhD, the study’s senior author. “The associations were more pronounced among subjects who were never smokers, diagnosed with squamous cell carcinoma or had less than 12 years of education.”

The team also found that the risk is not significantly affected by the GL index. “This suggests that it is the average quality, instead of quantity, of carbohydrates consumed that may modulate lung cancer risk,” Professor Wu said.

Elevated GI diets increased the risk of developing lung cancer by more than 50 percent in people who had never smoked, and by 31 percent among those in the smokers group. High GIs also raised the risk of developing SCC by more than 92 percent compared with a low GI index, which could be linked to higher levels of IGFs.

Other findings revealed that patients with low education levels (less than 12 years of schooling) and high GIs had a 77 percent increased chance of lung cancer, while those with higher education only had a 33 percent increased chance. This was linked to diet quality and non-smoking habits among people with higher education.

Professor Wu concluded, “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,”

As the study was limited to non-Hispanic whites, and did not account for diseases like diabetes, hypertension, and heart disease, the researchers plan to validate the findings in a future prospective cohort study that will include other ethnic groups.

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