Research Raises Questions about Statin Use and Inflammatory Breast Cancer
The headlines sounded promising. “Statins Reduce Recurrence for Inflammatory Breast Cancer Patients” they proclaimed. Then I read the full study published earlier this month that the headlines were based on. It was hard going, and I had to do plenty of backtracking to understand the language about statins.
Most people are familiar with these highly advertised drugs like Zocor (simvastatin) Lipitor, (atorvastatin) and Crestor (rosuvastatin). They are primarily used to lower cholesterol and reduce heart disease. Some scientists have suspected that their anti-inflammatory properties could also work on cancer tumors. In fact, a large Danish study published in 2011 found simvastatin (Zocor) users had about 10 fewer breast cancer recurrences per 100 women after 10 years.
Statins can be divided into two groups: fat-soluble and water-soluble. Simvastatin is in the fat-soluble group, and the Danish research found that only the fat-soluble statins reduced recurrence rate. There was no difference in recurrence for women taking water-soluble statins compared to women taking no statins.
Researchers at MD Anderson Cancer Center wanted to look at how statin use might affect inflammatory breast cancer (IBC). They went back through the records of women treated at the hospital from 1995 to 2005 and examined the history of 724 patients. Of these, 650 had never been prescribed a statin, and 74 had. Those who had never used a statin averaged 1.76 years of progression-free survival; the fat-soluble statin users survived 2.47 years on average progression free; and those taking a water-soluble statin survived 4.88 years without progression of their disease. In the IBC world, 4.88 years is huge, so it is not surprising that medical news services were headlining this study.
So what does this mean? Should any breast cancer patient ask her doctor to put her on a statin? And if she did, which kind should she ask for: water-soluble or fat-soluble? The studies contradict each other about which form of statin works best.
The huge question here is: are the statins responsible for the reduction in recurrence? These studies are retrospective. They examined the records of previous patients and notice a link between statin use and recurrence rates. The researchers themselves note the limitation of their study, “The treatment of statins was not randomly assigned but was determined at the initial evaluation of primary IBC. Medication compliance could not be confirmed and underreporting of statin use could be a potential source of error. Also the duration of statin use could not be assessed. Besides the indication for statin use, other possible confounding factors include other medications not included in this study, which may influence relapse, as well as lifestyle differences such as diet, exercise, alcohol and tobacco intake, socioeconomic status, and educational levels. Those who took statins may represent a population with better access to health care, a more health-conscious lifestyle and higher educational levels, thus potentially favouring a longer PFS [progression free survival] time.”
I wonder whether there could be other reasons besides the ones mentioned. Maybe there is something about having high cholesterol that offers some protection against recurrence. Maybe it is not the medication, but the underlying health conditions for which it is prescribed. The MD Anderson study calls for more research about if and how statins work against tumors.
Statins are powerful drugs with potential side effects, some serious. The list of contraindications for their use is long. They also cannot be used in combination with many common medications. It is much too soon for oncologists to start including a statin prescription in the treatment plan for every breast cancer patient. However, if you are on a statin already, you can draw some comfort from the possibility that it is reducing your chances of recurrence. If you are an IBC patient on a statin, you should talk to both your primary care doctor and your oncologist about whether one of the water-soluble statins (such as Crestor, Lipitor, or Pravachol) might be appropriate for you.
I started researching this topic looking for concrete answers and found only more questions. This morning the Writer’s Almanac quoted Thorstein Veblen, “The outcome of any serious research can only be to make two questions grow where only one grew before." By that measure both these studies were successful.
Ahern, T P et al. Statin prescriptions and breast cancer recurrence risk: a Danish nationwide prospective cohort study. J Natl Cancer Inst. 2011 Oct 5;103(19):1461-8. doi: 10.1093/jnci/djr291. Epub 2011 Aug 2. Accessed 30 July 2013 at http://www.ncbi.nlm.nih.gov/pubmed/21813413
Brewer, T M et al. Statin use in primary inflammatory breast cancer: a cohort study. British Journal of Cancer (2013) 109, 318–324. doi:10.1038/bjc.2013.342 www.bjcancer.com Published online 2 July 2013. Accessed 30 July 2013 at http://www.nature.com/bjc/journal/v109/n2/full/bjc2013342a.html