Risikofaktorer – røyking og lungekreft

Søknadssammendrag

Påvirkning av vitamin D-mangel, astma/allergi og stillesittende livstil på lungekreft i en norsk befolkning

Sluttrapport

Bakgrunn

Lung cancer is one of the most common cancer types with a low survival rate worldwide. Although smoking is the most important risk factor for lung cancer, many people with lung adenocarcinoma, the most common lung cancer subtype, are non-smokers. Given the increasing incidence of lung cancer is mainly accounted by adenocarcinoma, other potential risk factors than smoking such as a sedentary lifestyle, asthma and obesity may play important roles for the development of lung cancer. In this project, we therefore used data from The Trøndelag Health Study (HUNT) and Cancer Registry of Norway to study whether these three risk factors were associated with lung cancer risk. The first two studies are prospective cohort studies, while the last one focuses on the potential causal association between BMI and lung cancer incidence using both traditionally observational methods and Mendelian randomization (MR) with genetic variants as instrument variables for exposures.

Resultater

The results suggested that people who were mostly sedentary were at an increased risk of developing lung cancer. Intervention targets could therefore focus on the most sedentary group of people, whose risk of lung cancer may be reduced by replacing a sedentary lifestyle. People who had partially controlled asthma also had an increased risk of lung cancer. Proper control of asthma symptoms might also contribute to a reduced incidence of lung cancer. Since non-small cell lung cancer is the major subtype of lung cancer and is relatively insensitive to chemotherapy, this finding has important implications for healthcare with regard to both asthma and lung cancer. However, the results should be interpreted with caution since residual confounding by smoking and unmeasured confounding cannot be completely excluded in observational studies. The discrepancy of findings between the observational and MR analysis suggested that the observed inverse association between BMI and lung adenocarcinoma might not be causal. If a positive association is proven by future MR studies, reducing body weight will be an important prevention target for lung adenocarcinoma.

Oppsummering

Through contact with users, we found that association between overweight/obesity and cancer risk might be an important topic since many patients were overweight before they got cancers. Luckily, we have data to do research on this. Thus, the topic for the last study in this project was changed to causal association between BMI and lung cancer risk. We included Mendelian randomization method, a new method to understand better on the causal association by using genetic data as instrument variable in this study. All studies have been done and results were shown in three published papers and my thesis.