HEALTH NEWS

Study Title:

Low Cholesterol Associated with Cancer and Death

Study Abstract

Background: The risk association between low-density lipoprotein (LDL) cholesterol and cancer remains controversial and largely unexplored for people not receiving statin therapy.

Methods: We examined the risk association between LDL cholesterol and cancer among patients with type 2 diabetes mellitus who were free of cancer at enrolment and whose statin use was known. We considered a variety of nonlinear relationships in our analysis.

Results: During a median follow-up period of 4.90 years, cancer developed in 270 (4.4%) of 6107 patients. Among the 3800 patients who did not receive statin therapy, the risk association between LDL cholesterol and cancer was represented by a V-shaped curve. Compared with patients whose LDL cholesterol was at least 2.80 mmol/L but less than 3.80 mmol/L, the risk of cancer, death from any cause or the composite outcome of cancer or death was greater among those with an LDL cholesterol level of less than 2.80 mmol/L (hazard ratio for cancer 1.74, 95% confidence interval [CI] 1.20–2.52) and those with an LDL cholesterol level of 3.80 mmol/L or greater (hazard ratio for cancer 1.87, 95% CI 1.29–2.71). Using 3.8 mmol/L as a reference
point, we found that the hazard ratio for cancer for every millimole per litre absolute change in LDL cholesterol was 1.54 (95% CI 1.19–1.99) among patients not using statins; the hazard ratio was reduced to 1.24 (1.01–1.53) for the entire sample (statin users and those not using statins). These associations persisted after adjustment for covariates and exclusion of patients with less than 2.5 years of follow-up.

Interpretation: Among patients with type 2 diabetes, the association between LDL cholesterol and cancer was Vshaped, whereby both low and high levels of LDL cholesterol were associated with elevated risk of cancer.

From press release:

Low cholesterol associated with cancer in diabetics
Low levels of LDL cholesterol as well as high levels are associated with cancer in patients with type 2 diabetes, found a prospective cohort study published in CMAJ.

Researchers from the Hong Kong Institute of Diabetes and Obesity, the Li Ka Shing Institute of Health Sciences and The Chinese University of Hong Kong conducted a study of 6107 Chinese patients with type 2 diabetes and found a V-shaped risk relation between LDL cholesterol and cancer in patients not receiving statin therapy.

"LDL cholesterol levels below 2.80 mmol/L and levels of at least 3.90 mmol/L were both associated with markedly elevated risk of cancer among patients who did not use statins," state Dr. Juliana Chan and coauthors.

The study excluded people on statins as statins obscured the association between LDL cholesterol and all-site cancer.

Increasing data suggests an association between type 2 diabetes and an elevated risk of cancer, including breast, colorectal, pancreatic and liver cancers. An elevated risk of cancer in patients with low LDL was linked to cancers of digestive organs and peritoneum, genital and urinary organs, lymphatic and blood tissues as well as other areas. Patients with an LDL cholesterol level above 3.80 mmol/L had heightened risks of oral, digestive, bone, skin, connective tissue, breast and other cancers.

Regarding clinical implications, the authors suggest "the use of these levels as risk markers may help clinicians to assess their patients more fully and thus to prevent premature deaths in patients who have high risk."

They call for re-analysis of data from clinical trials to confirm or refute these findings.

Study Information

Xilin Yang PhD, WingYee So MBChB, Gary T.C. Ko MD, Ronald C.W. Ma MBChB, Alice P.S. Kong MBChB, Chun-Chung Chow MBBS, Peter C.Y. Tong PhD, Juliana C.N. Chan MD
Independent associations between low-density lipoprotein cholesterol and cancer among patients with type 2 diabetes mellitus.
Canadian Medical Association Journal
2008 August
Hong Kong Institute of Diabetes and Obesity