ASA and Breast Cancer

Aug 12, 2014

By Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy

Why didn't Noah squat the two mosquitoes? I still get a chuckle out of that one. Mountain View Christian Assembly on Whitmore Ave E often has some very amusing quips on the sign in their parking lot. I seem to be drawn to their sign on my bike rides to see if the message has changed. But it is a provocative question. If Noah had squatted the two mosquitoes, Pat and I wouldnt have had to sleep with screens draped over our heads on a recent fishing trip. And more seriously diseases like West Nile Virus and malaria wouldnt be able to spread. Noah had a simple solution to the complicated mosquito problem but chose not to use it. Is there a simple solution to the complicated breast cancer problem that we are choosing not to use?

Dr. Michelle Holmes from Harvard University looked a long running study called the Nurses Health Study. Specifically she looked at a subsection of 4000 women in the study with breast cancer. These women had already undergone normal breast cancer treatment including surgery, chemotherapy and radiation. Dr. Holmes noticed that in this group, if the women happened to be taking ASA for some other reason, they were 50% less likely to die from their cancer as women who weren't on ASA. This was a fascinating observation, but Dr. Holmes would have to run more trials to prove it wasn't a fluke. That's where we started missing the simple solution.

We have known about ASA for a long time. Hippocrates, the Greek healer who is known as the father of western medicine, wrote about powdered willow bark over 2500 years ago. White willow bark was used to treat pain and fever. A couple thousand years after Hippocrates, chemists identified the active ingredient in white willow bark as salicin. In the late 1800s chemists at the Germany company Bayer made a synthetic version of salicin. This eventually became ASA or acetylsalicylic acid. Bayer gave ASA the trade name Aspirin.

ASA does interesting things in the body. It affects the enzyme cyclooxygenase and this decreases the pro-inflammatory chemicals the prostaglandins. We think that decreasing these prostaglandins is what causes ASA to be able to decrease pain and inflammation. We think that the decrease of the prostaglandin E1 in the brain is what causes ASA to be able to decrease fever. ASA also affects platelets. Platelets help your blood to clot. ASA stops the cyclooxygenase enzyme in the platelet from forming thromboxane. This permanently disables the platelet from being able to clot for the life of the platelet which is 7 to 10 days.

This leads to what we usually use ASA for. The Heart and Stroke foundation of Canada says every 7 minutes someone in Canada dies of heart disease or stroke. Daily use of ASA can prevent heart attacks and stroke. We have to be careful, though. ASA can also lead to stomach bleeding, so have to balance the risk of bleeding versus the benefit of preventing heart attack and stroke in each individual patient.

Does daily, long term low dose ASA do other good things? Maybe. Researchers now think ASA may also help fight cancer. In the March 11, 2013 online version of Cancer, Tang et. al looked at the Womens Health Initiative study and showed women taking ASA had less chance of getting a skin cancer called melanoma. Thats good, but a previous study looked at the same Womens Health Initiative study and found ASA did not prevent colorectal cancer. In March 2012 issues of the Lancet and Lancet Oncology researchers led by Peter Rothwell and John Radcliffe looked at a bunch of ASA trials. In one meta-analysis they looked at 51 studies in which some people were put on ASA to prevent heart attacks and strokes and some werent. The ones who werent put on ASA got cancer more often. In another paper they looked at 5 big ASA trials to prevent heart attack and stroke. They were looking to see how cancer spread or metastasized. Again the people on the ASA had less cancer spread than those not on ASA. Although these papers are very interesting, they arent randomized, double blind placebo controlled trials. The patients they were looking at were actually heart patients, some of which happened to have cancer. Ideally we would like to see a large group of people without cancer half be given a sugar pill and half be give low dose ASA. Then after a number of years the researchers would check to see which group got cancer more often. Then we would like to see a trial in which a large number of people with cancer are half given a sugar pill and half given ASA and see in which group the cancer spreads the fastest. That way we would have a better idea if this ASA effect on cancer is real or not.

Those are the kind of studies Dr. Michelle Holmes would need to run to prove ASA really reduces the breast cancer death rate by 50%. She estimates those studies would cost about $10 million. So far Dr. Holmes has been turned down for funding by US funding agencies four times. Drug companies fund lots of multi-million dollar drug trials. But no drug company would be interested in funding an ASA trial because there is no money to be made. Drug companies fund trials in hopes of getting a patent on a popular drug. The patent allows them to exclusively sell a drug for a certain number of years. That is when the drug company makes its money to fund drug trials and create value for its shareholders. Since the patent on ASA expired decades ago, no drug company could profit off a new use for an old drug. It is tempting to blame the drug companies, but finding new uses for old drugs really isn't their role. In a publicly funded health care system like Canada, one group that would financially benefit a lot from a new breast cancer treatment. They would especially benefit if the treatment was an inexpensive as ASA. That group is the provincial ministries of health. To be fair, Dr. Holmes is an American researcher, and I dont know if she has approached Canadian Funding Agencies, but I think they should consider reaching out to her.

I think we really are missing a Noah-mosquito moment here. Why didn't Noah squat the two mosquitoes? I don't know. Why wouldnt the federal or provincial governments fund research that could reduce death from breast cancer and save money? That makes even less sense that allowing Manitoba's flying vampires buzz in my ears as I try to sleep.

As always if you have any questions or concerns about these products, ask your pharmacist.

The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

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Dr. Michelle Holmes OpEd in New York Times:

John LaMattina, former head of R&D for Pfizer blog for Forbes

CBC report :


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