Popular Statin Cuts Breast Cancer Recurrence Rate By 30%

Simvastatin, a popular statin, may cut the rate of breast cancer recurrence by as much as 30% according to the results of a recent study conducted by American and Danish researchers.

The study, published in October, in the Journal of the National Cancer Institute, involved almost 18,769 Danish women who were diagnosed with stage 1-3 breast cancer between 1996 and 2003. The women were followed up for an average of 6.8 years. Slightly under 20% of breast cancer patients were prescribed statins following their diagnosis. The majority of patients were prescribed lipophilic statins (meaning they dissolve easily in fat) rather than hydrophilic statins. Simvastatin was the most prescribed statin, accounting for 92% of all lipophilic statin prescriptions.

The researchers found that the women exclusively prescribed lipophilic statins were much less likely to suffer a breast cancer recurrence event than either non users, or those using hydrophilic statins. The breast cancer recurrence risk was 19.4% for lipophilic statin users compared to 35% for hydrophilic statin users and 30.2% for nonusers. The researchers also calculated that exclusive simvastatin users would have 10 fewer breast cancer recurrences per 100 women over a ten year period following breast cancer diagnosis compared to non-statin users, a reduction in relative risk of 30%.

The researchers believe that the findings of this study should be enough to prompt a larger, randomized clinical trial to determine the effectiveness of lipophilic statins in treating breast cancer.

While the precise mechanisms behind why some statins, but not others, appear to reduce breast cancer recurrence risk are largely unknown, other studies have found that only lipophilic statins appear to induce apoptosis and inhibit proliferation of cancer cells in vitro. A 2009 study found that lipophilic, but not hydrophilic statins induced apoptosis in ovarian, endometrial and cervical cancer cells while a 2006 study found that simvastatin induced apoptosis in both ER+ and ER- human breast cancer cell lines. Finally a study conducted in 2003 by German researchers looked at the effects of 5 statins: atorvastatin, fluvastatin, lovastatin, pravastatin and simvastatin, on the proliferation of human breast cancer cells. All statins reduced cell proliferation by around 90% with the exception of pravastatin which was the only hydrophilic drug.

Simvastatin was developed by Merck & Co and first introduced in the USA under the brand name Zocor in 1990. It went on to become one of the most popular statins worldwide grossing more than $4.3 billion in 2005, second only in statin sales to Lipitor which grossed in excess of $12 billion worldwide. In 2006, Merck lost its patent protection leading to a large drop in price as generic simvastatin products hit the market. Simvastatin remains a very popular statin to this day due to its effectiveness, low price, and relatively good safety profile.