Time trends in serum cholesterol before cancer death

Following evidence of an association between low serum cholesterol and cancer from several prospective studies, this paper concentrates on individual time trends in serial measurements of serum cholesterol before a cancer-related death. The Framingham Heart Study contains repeated measurements of cholesterol at approximately 2-year intervals in 5,209 subjects, of whom 539 died from cancer during 30 years of follow-up. We quantify (1) the change in serum total cholesterol level before cancer death, and (2) the association between fall in serum total cholesterol and odds of cancer death. The mean fall in serum total cholesterol in the 4- to 6-year period before cancer death is 8.06 (95% confidence interval = 4.58-11.54) mg per dl, with some evidence of lowered cholesterol before that period. This pattern is corroborated by evidence of a substantially increased odds of cancer death if a large fall in cholesterol occurs over any 4- to 6-year period. We suggest that these time trends can plausibly be attributed to the effects of prevalent cancer on lowering serum cholesterol; our findings add weight to the argument that the low cholesterol-cancer mortality relation does not arise because of any causal contribution of low serum total cholesterol to the risk of cancer.