Editorial Cholesterol and Cancer: Answers and New Questions

Many epidemiologic studies published in the 1980s docu-mented an association between low circulating cholesterol and higher overall cancer incidence and mortality (1). This association has been attributed to reverse causation, that is, undiagnosed cancer causing a reduction in cholesterol le-vels. Reverse causation is strongly supported by observa-tions that cholesterol levels decline before cancer diagnosis (2, 3) and that associations between low cholesterol and cancer incidence and mortality weaken when the first few years of study follow-up are excluded (4). In addition, a meta-analysis of randomized trials of cholesterol-lowering statins found no effect on risk of cancer, although only short-term effects could be addressed due to the short duration of most trials (5). Despite strong evidence for re-verse causation, it has been difficult to entirely rule out th