High Cholesterol Levels Lower Risk of Colorectal Cancer

It has long been known that statins (drugs used to lower the abnormally high levels of cholesterol in the body) and cholesterol tend to lower the risk of colorectal cancer. Recent research has established that it is the high cholesterol level, and not statins, that actually proves beneficial in lowering the risk of colorectal cancer.

This large scale case-control study was led by Ronac Mamtani, MD, MSCE and assistant professor of Hematology/Oncology from the Perelman School of Medicine at the University of Pennsylvania and the Abramson Cancer Center. The study was later published in PLOS Medicine.

During the course of the study, analysis of 100,000 patients' medical records was done. The basic aim of the study was to assess the role of both statins and high cholesterol in decreasing the risk of colorectal cancer.

The researchers compared the use of statins and blood cholesterol level between 22,163 patients with colorectal cancer (cases) and 86,538 patients without colorectal cancer (controls). The data was obtained from electronic records of over 10 million patients from primary care practices in the United Kingdom.

High Cholesterol Helps against Colorectal Cancer

It was found out that it was actually the “indication” bias that caused statins to be previously linked with decrease in the risk of colorectal cancer. Indication bias arises when an indication for using a drug (high cholesterol, in this case) and the drug being used (statins) both result in the same outcome (low risk of colorectal cancer, in this particular case).

It was found out that there was no significant difference in the risk of developing colorectal cancer between patients using statins and those not using it. When the researchers looked for the impact of blood cholesterol, statistically significant data was found. It was observed that for every 1 mmol/L (nearly 38.6 mg/dl) increase in total cholesterol level in the blood, the risk of development of colorectal cancer dropped by 10%.

The study established an inverse relationship between the levels of cholesterol and the risk of developing the colorectal cancer. The higher the level of cholesterol in the body, the lower is the risk of colorectal cancer.

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The researchers also came up with an unexpected finding. They found an unexplainable reduction in the levels of cholesterol (more than 1 mmol/L) a year before the diagnosis of colorectal cancer in both the groups-patients using statins and those not using it. A 1.25-fold increase in risk of colorectal cancer was observed in people using statins as compared to 2.36-fold increased risk in the non-users.

These findings suggest that cholesterol levels in the body play a much bigger role than appears to the eye. It was postulated that the blood levels of cholesterol can, therefore, be used as a biomarker for the detection and monitoring of colorectal cancer in high risk patients.

The Future Prospects

The study has helped understand the intricate relationship between the use of statins, high blood cholesterol levels and the risk of colorectal cancer. This unexplainable drop in blood cholesterol before the diagnosis of colorectal cancer has prompted further research into its cause along well the prospect of using it as a biomarker for the detection of colorectal cancer.