Tufts Medical Center Researchers Find Link Between
Low Cholesterol Levels and Cancer
Boston, Mass. -- Millions of Americans take statins to lower their cholesterol, but how low is considered too low? Many scientific studies support the benefits of lowering low density lipoprotein (LDL) cholesterol and believe achieving low LDL cholesterol levels is one of the most important steps in preventing heart disease. New research, however, provides evidence for an association between low LDL levels and cancer risk.
A Tufts Medical Center study, published in the July 31st issue of the Journal of the American College of Cardiology (JACC), investigated how and why statins cause side effects, particularly damage to the liver and muscle cells. The key message of the study supports taking multiple medications rather than high-dose statins to minimize those side effects. The researchers did not expect to find the increased cancer risk (one additional incident per 1,000 patients) from low LDL levels, and additional studies have already begun to investigate this potential risk further. Future studies will aim to confirm the risk and to identify whether the risk may be a side effect of statins or just low LDL.
“This analysis doesn’t implicate the statin in increasing the risk of cancer,” said Richard H. Karas, MD, PhD, FACC, lead author and Director of Tufts Medical Center’s Preventive Cardiology Center. “The demonstrated benefits of statins in lowering the risk of heart disease remain clear; however, certain aspects of lowering LDL with statins remain controversial and merit further research.” Dr. Karas emphasized that patients are advised to continue their statin treatments and, as always, consult their doctor before discontinuing use of any medication.
The researchers evaluated randomized controlled statin trials published before November 2005. They looked at 13 treatment arms consisting of 41,173 patients and assessed absolute change and percentage of change in LDL reduction and the resulting achieved LDL levels in relation to rates of newly diagnosed cancer in each treatment arm. They also looked at the relationship between low, intermediate and high doses of statins and rates of newly diagnosed cancer. They did not find a relationship between percent of change and absolute change in LDL levels, but they observed higher rates of newly diagnosed cancer among patients with lower achieved LDL levels. In addition, the new cancers were not of any specific type or location.
Recent data from large-scale statin trials have shown that more intensive LDL lowering can provide significant cardiovascular benefits to higher-risk patients. In response to these findings, recent national guidelines have advocated for lower LDL goals and higher doses of statins to reach them. However, informal observations linking intensive LDL lowering and higher incidence of reported health problems (including liver and muscle toxicity and cancer) has introduced some concern over the safety of such treatments. These concerns, in part, prompted the current study.
The current findings are not definitive, as limitations of the study show. Researchers performed their analysis from summary data taken directly from published manuscripts of each trial. An analysis based on data for each individual patient would have yielded more specific and potentially more compelling results, said Dr. Karas.
For this portion of the study, researchers analyzed 23 statin treatment arms that included 75,317 patients with a combined 309,506 years of follow up. A link between LDL lowering and liver or muscle irritation was not found. However, liver toxicity levels increased with higher statin dosage. Based on their findings, Tufts Medical Center researchers concluded that moderate-dose therapy with multiple medications including statins may prove to be preferable to high-dose therapy with statins alon
“As we’ve seen in treating high blood pressure, using combinations of multiple medications at moderate doses may also prove to be the best approach to lowering bad cholesterol,” said Dr. Karas. “Our study focused on better understanding the risks associated with statin treatment so that we can better weigh them against the benefits to give our patients the best care possible. As such, the current findings do not diminish the importance of taking statins to lower heart attack risk.”