Background: Although
insulin may increase the risk of some
cancers, few studies have examined fasting serum
insulin and
lung cancer risk.Methods: We examined serum
insulin,
glucose, and indices of
insulin resistance [
insulin:
glucose molar ratio and homeostasis model assessment of
insulin resistance (HOMA-IR)] and
lung cancer risk using a case-cohort study within the
Alpha-Tocopherol,
Beta-Carotene Cancer Prevention Study of Finnish men. A total of 196 cases and 395 subcohort members were included.
Insulin and
glucose were measured in fasting serum collected 5 to 12 years before diagnosis. Cox proportional hazards models were utilized to estimate the relative risk of
lung cancer.Results: The average time between blood collection and
lung cancer was 9.6 years. Fasting serum
insulin levels were 8.7% higher in subcohort members than cases. After multivariable adjustment, men in the fourth quartile of
insulin had a significantly higher risk of
lung cancer than those in the first quartile [HR = 2.10; 95% confidence interval (CI), 1.12-3.94]. A similar relationship was seen with HOMA-IR (HR = 1.83; 95% CI, 0.99-3.38). Risk was not strongly associated with
glucose or the
insulin:
glucose molar ratio (Ptrend = 0.55 and Ptrend = 0.27, respectively).Conclusions: Higher fasting serum
insulin concentrations, as well as the presence of
insulin resistance, appear to be associated with an elevated risk of
lung cancer development.Impact: Although
insulin is hypothesized to increase risk of some
cancers,
insulin and
lung cancer remain understudied. Higher
insulin levels and
insulin resistance were associated with increased
lung cancer risk. Although smoking cessation is the best method of
lung cancer prevention, other lifestyle changes that affect
insulin concentrations and sensitivity may reduce
lung cancer risk.
Cancer Epidemiol
Biomarkers Prev; 26(10); 1519-24. ©2017 AACR.