PTGS2 and lung cancer: Given the importance of ethnic divergences in the genetic effects on complex diseases and the fact that genetic markers for proposed gene-disease associations vary in frequency across the populations, we evaluated five extensively studied polymorphisms in PTGS2 (rs689466, rs5275, rs20417) and CYP2E1 (rs2031920, rs6413432) genes in a large northeastern Chinese population to examine their associations, both individually and in combination, with lung cancer risk.