MedicalResearch.com Interview with:
Xifeng Wu, M.D., Ph.D
Professor of Epidemiology and
Dr. Stephanie Claire Melkonian PhD
Epidemiologist, Postdoctoral Research Fellow
The University of Texas MD Anderson Cancer Center
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Glycemic index (GI) assigns foods an indexed value to show how quickly and how much carbohydrates in the food cause blood glucose levels to rise after eating and is a measure of overall carbohydrate quality. Glycemic load (GL) is a related measure that is calculated by multiplying Glycemic index by the amount of carbohydrates in grams in that specific food and by the amount consume, then dividing by 100. Previous studies have investigated the association of GI and GL with certain types of cancer, including colorectal, stomach, and pancreatic cancer, but there has been limited research into the association with lung cancer.
We conducted a study using patients and control subjects from an ongoing case-control study of lung cancer conducted at MD Anderson. The patients were newly diagnosed and had not received treatment other than surgery. The healthy control subjects were selected from patient lists at Kelsey-Seybold Clinics, a large physician group in the Houston area. The study results encompass 1,905 cases and 2,413 controls. Using data collected from in-person interviews regarding health histories and dietary behaviors, we were able to categorize the study subjects according to their dietary Glycemic index and GL.
What we found was that individuals in the highest category of GI were at an almost 50% increased risk for developing lung cancer as compared to those in the lowest group. This association was different based on different subtypes of cancer. Most interestingly, however, among those individuals that never smoked, high Glycemic index was associated with an almost 2 fold increased risk of lung cancer. In other words, we found a more profound association between GI and lung cancer in never smokers in this study.
MedicalResearch.com: What should clinicians and patients take away from your report?
Response: Monitoring carbohydrate intake, in particular in relation to high Glycemic index foods, may be an important part of cancer prevention when we consider it jointly with a healthy diet high in fruits and vegetables, an active lifestyle, and healthy body weight. GI may be one factor that contributes to lung cancer, in particular among those that have not smoked. In individuals that smoke, smoking is still a major and the most well-characterized risk factor for lung cancer. Reducing consumption of high GI foods, in particular processed foods with a lot of added sugars, may help reduce cancer risk.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: In future studies, it would be helpful to evaluate the role that hypertension, diabetes, and heart disease play in the association between Glycemic index and lung cancer risk. Additionally, further research should examine whether dietary changes can have an effect on cancer-related biomarkers, and whether these associations are consistent in other racial or ethnic groups.
MedicalResearch.com: Is there anything else you would like to add?
Response: While GI is associated with an increased risk of lung cancer, particularly in never smokers, it is important to realize that the life time risk of lung cancer, particularly in never smokers, is still extremely low. GI is potentially just one contributing factors to the increased risk of lung cancer in this population and this study adds to the growing literature that indicates that overall diet quality, and other modifiable risk factors like obesity and physical activity, play an important role in cancer prevention.
C. Melkonian, C. R. Daniel, Y. Ye, J. A. Pierzynski, J. A. Roth, X. Wu.Glycemic Index, Glycemic Load, and Lung Cancer Risk in Non-Hispanic Whites. Cancer Epidemiology Biomarkers & Prevention, 2016; 25 (3): 532 DOI: 10.1158/1055-9965.EPI-15-0765
Dr. Xifeng Wu and Dr. Stephanie Claire Melkonian (2016). High Glycemic Index May Raise Lung Cancer Risk Especially in Never Smokers