ASA and Cancer

Feb 23, 2016

By Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy

You learn the most surprising things while fishing. Last summer, I learned about iPhone maintenance. We were comparing wild life videos with some guys in the next boat who ran Lopez Foods in the States. One of them commented about all the space video's and pictures take up when you receive them as text messages from your kids. I used that fishing info to make space on a co-worker's iPhone so she could run updates and load new software. On the long weekend, I learned how front line shelter workers deal with potential lice, scabies and bed bugs in their clothes. Pat's son, Brent, came winter camping with us this year at Singush Lake. We fished on Gull Saturday and Sunday. Brent had never been fishing before, so he had to show everyone up by catching a 19 inch Rainbow Trout. It was just shy of being a master angler. Not a bad first fish at all. Brent does many interesting things back home in Ottawa. He flies out to remote reserves and teaches science. He works on an organic farm. And he works at a couple homeless shelters. It could be very easy for front line workers like Brent to bring lice, scabies and bed bugs home from work in their clothing. But they have a surprising strategy.

Scientists have learned some surprising things about ASA or aspirin lately. Dr Cornelia UIrich, of the Huntsman Cancer Institute in Salt Lake City, thinks her team may have found one of the reasons why ASA might reduce colorectal cancer.

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 1800's 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 in appropriate patients. We have to be careful, though. ASA can also lead to stomach bleeding, so we 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 Women's Health Initiative study and showed women taking ASA had less chance of getting a skin cancer called melanoma. That's good, but a previous study looked at the same Women's 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 weren't. The ones who weren't 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 were very interesting, they weren't 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.

While we are waiting for a large trial to tell us if the effect of ASA on colorectal cancer is real or a fluke, Dr. Ulrich published a paper in the journal of Cancer Epidemiology, Biomarkers, and Prevention. Dr. Ulrich's team looked the metabolites that 40 people produced while on ASA for 60 days. They looked at over 360 different metabolites and found a significant reduction in 2-hydroxyglutarate in the people taking ASA. Scientists think 2-hydroxyglutarate is linked to tumor formation and growth. This is exciting because we didn't really know why ASA might reduce the amount of colorectal cancer. It was hypothesized that ASA's antiinflamatory and blood thinning effects might be involved. However, Dr. Ulrich's discovery of 2-hydroxyglutarate reduction, might be a completely separate and surprising good thing ASA is doing to reduce colorectal cancer.

Front line shelter workers like Brent have a surprising way to treat their clothes to prevent lice, scabies and bed bugs. At the end of their shift, they remove their work clothes and seal them in plastic garbage bags. Then when they get home they immediately put them in the dryer. Then wash them. Then dry again. So dry-wash-dry. The dryer will kill the buggies. The washing machine gets rid of the buggy bodies and dirt. The second dry kills off any possible hardy buggies that lived through the first dry and wash. Now I can kill bed bugs too, and I learned all of that while fishing.

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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