Is Aspirin a Cancer Preventative?
Aspirin knows how to multitask. It was originally developed more than a century ago as a pain reliever, but it was soon discovered that it also reduces fever and fights inflammation. In the last 30 years it was found that a daily low dose of aspirin reduces the risk of heart attacks and strokes. And now a new study suggests that aspirin taken over an extended time period reduces the risk of death from a variety of solid tumor cancers, including colorectal, lung, esophageal, and gastrointestinal cancers.
The study tracked cancer death rates among 25,570 individuals who had participated in eight different randomized clinical trials of aspirin, all of which ended years ago. The participants in the clinical trials were divided into two groups: one that received a daily dose of aspirin and one that received a sugar pill. Twenty years later, participants who had received aspirin were 20 percent less likely to have died of solid tumor cancers than those who had not taken aspirin. This reduction in cancer deaths was most dramatic among individuals who had participated in the longest trials.
For all its medical benefits, aspirin is a remarkably simple molecule. It is a chemical derivative of salicylic acid, which was first extracted from willow bark and is still used in face washes to treat acne. Aspirin was first made in a laboratory over 150 years ago although its chemical and medicinal properties were not well understood at the time. Since then scientists have discovered that aspirin offers many surprising therapeutic effects, including the new findings about aspirin’s effect on the development of cancer. Exactly how aspirin reduces the risk of cancer death is unknown. The drug’s anti-inflammatory properties may slow the early development of cancerous tumors. Or aspirin may somehow kill early cancer cells outright.
In an interview with the New York Times, the study’s lead author, Dr. Peter Rothwell, pointed out that a lot of research has been done showing that exposure to certain chemicals can increase the risk of developing cancer, but this is the first study that suggests that long-term exposure to a simple chemical, aspirin, could reduce the risk of developing cancer. Even so there are risks associated with long-term aspirin use, such as indigestion and, more seriously, stomach bleeding and strokes. So many doctors and other researchers have urged caution and called for more research before recommending that patients take aspirin solely as a cancer preventative.
The Long Road Ahead for Other Preventive Drugs
The study highlights the difficulties faced by drugs designed to prevent disease. A variety of preventive drugs, which must be taken over an extended period of time to show an effect, are currently being used or developed to fight serious diseases such as HIV/AIDS, Alzheimer’s, and cancer, among others. Usually these drugs are only intended for people who have a high risk of developing the targeted disease as determined by lifestyle or genetic factors. But the problem with preventive drugs is that they are given to healthy people. All drugs have side effects, but side effects that are considered acceptable for a patient with terminal cancer would not be considered acceptable for a healthy person. This means that preventive drugs need to be much safer than drugs used to treat active diseases. On top of this, proving that a drug actually prevents a disease is no easy task. Like the aspirin study, a large sample size and an extended observation period are needed to get reliable results.
But despite these obstacles, preventive drugs remain a promising strategy in the fight against certain diseases, such as Alzheimer’s. Alzheimer’s is still poorly understood, and once the disease has caused neurological damage in a patient, its debilitating symptoms are often irreversible. So a strategy of preventing or slowing the development of the disease makes sense. Yet many pharmaceutical companies are reluctant to risk the massive commitment of time and money needed to conduct clinical trials that show that a drug effectively prevents Alzheimer’s. And even if the necessary trials were undertaken, it could be decades before the drug is approved by the FDA and marketed.
If a drug such as aspirin, which has been used for over a century and is available over the counter, struggles to gain widespread recognition as a preventive cancer drug, is there any hope for the development of new preventive drugs? Given the difficulties surrounding the testing of preventive drugs, some might argue that resources would be better allocated to developing drugs for the treatment of active diseases. Many patients may also be resistant to the idea of long-term use of a medication to prevent an illness that they have yet to develop, although millions of people already do so to prevent heart disease. Even so, the results of the aspirin study show that the rewards of preventive drug development in terms of human lives saved could be great.
Rothwell, P., Fowkes, F., Belch, J., Ogawa, H., Warlow, C., & Meade, T. (2010). Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomised trials The Lancet DOI: 10.1016/S0140-6736(10)62110-1