In a study of Chinese patients with type 2 diabetes, very low levels of LDL-cholesterol (the "bad" type), as well as very high levels, were associated with an increased risk of mortality and cancer, investigators report in the Canadian Medical Association Journal.
"A V-shaped association between LDL cholesterol and cancer risk suggests that multiple mechanisms are involved," editorialists at the Harvard School of Public Health point out, adding that "LDL cholesterol is unlikely the sole or direct causal factor."
In their research, Dr Juliana C. N. Chan and colleagues at The Chinese University of Hong Kong analysed data from the Hong Kong Diabetes Registry, which includes 6107 patients age 35 and older with no history of cancer at enrolment between 1996 and 2005.
During an average follow-up of 4.9 years, cancer developed in 270 (4.4 percent), including 209 cases (5.5 percent) among the 3800 patients not treated with statins and 61 cases (2.6 percent) among those receiving statins. Patients with the lowest risk had LDL levels between 2.8 and 3.8 mmol/L. In further analysis, patients with LDLs of less than 2.80, mmol/L had a 74-percent increased risk of cancer compared with 53 percent among all subjects. Those with LDL levels of 3.80 mmol/L or higher had a 87-percent increased risk.
Similar patterns of risk were observed for mortality and for the composite outcome of all-site cancer and all-cause death.