Low total cholesterol levels could be sign of cancer

Having a low total cholesterol level could be a sign of undiagnosed cancer rather than a cause, new research has suggested.

Two studies reported this week in the journal Cancer Epidemiology, Biomarkers and Prevention, offer new insights into the relationship between cholesterol and cancer.

Cholesterol is carried in the bloodstream by lipoproteins, both high-density (HDL) particles and low-density (LDL) particles.

The problem has been that while having low levels of total cholesterol and particularly the “bad” LDL variety has been shown to protect against heart attacks, people with low cholesterol have also been found to have a higher risk of certain types of cancers.

But the new research suggests this relationship may be back to front and low cholesterol may be an indicator of cancer already present.

One of the studies was an 18-year study of nearly 30,000 Finnish male smokers, the largest and longest of its kind.

About a quarter of the men (7,545) developed cancer during that period.

Men with total cholesterol levels below 230 mg/decilitre (6 millimoles per litre) had an 18% higher risk of cancer overall.

But this risk was found to disappear when cancers that occurred in the first nine years of the study were excluded.

“Our study affirms that lower total cholesterol may be caused by undiagnosed cancer,” said Dr. Demetrius Albanes, a senior investigator at the National Cancer Institute.

The study also found that men with high levels of HDL or “good” cholesterol (above 40 mg/L or 1 mmo/L) had a 14% lower cancer risk even after excluding cases from the first nine years.

Another study of more than 5,000 US men by researchers at John Hopkins University in Baltimore found that men with low cholesterol (below 200 mg/deciliter or 5.2 mmo/l) had a nearly 60% lower risk of high grade prostate cancer.

Note - New Zealand doctors use the millimoles per litre measurement for cholesterol levels rather than milligrams per decilitre.

To convert from mg/dL to mmo/L divide the mg/dL by 38.7 (40 for a rough estimate).