Today, scientific advancements in cancer research seem to teeter on the edge of futuristic science fiction. Genetically engineered viruses, proton therapy, vaccines that coat cancer in RNA, and liquid biopsy technology are quickly establishing themselves as regulars in mainstream scientific journals.
In the midst of this incredible, ground-breaking work, a team of researchers at the Center for Molecular Medicine in Norway are returning to the simpler, well-known and widely available drug, aspirin, as a possible cancer treatment. Recently, the team published the results of their study – which included 23,162 Norwegian patients with colorectal cancer — in the Journal of Clinical Oncology.
This study was an observational, retrospective study meaning the researchers played no role in dictating whether or not the participants regularly received aspirin. Instead, the researchers simply sifted through the Cancer Registry of Norway, a database that details information on each occurrence of cancer nation-wide, looking for any patient that had been diagnosed with colorectal cancer. Researchers identified 23,162 patients that had such a diagnosis between 2004 and 2011.
Colorectal cancer, Credit: http://www.orlandogidoc.com/images/colon-cancer-screening.jpg
Next, the researchers used a second nation-wide medical registry, the Norwegian Prescription Database, which contains data on all prescription drugs prescribed to individuals since 2004, to identify which of those 23,162 cancer patients had a prescription for aspirin. Overall, the researchers found that 10,368 or 44.8% of those individuals had aspirin prescriptions. Because the researchers could not confirm whether or not those individuals had actually taken the aspirin or were just prescribed the drug, only those patients that received three or more aspirin prescriptions were included in the aspirin-user cohort (as patients who are actually taking the drug are more likely to need and seek out additional prescriptions). 6,102 patients or 26.3% met this criterion of being “exposed to aspirin.”
Of the 6,102 patients that were diagnosed with colorectal cancer and were exposed to aspirin, 2,071 patients or 32.9% died between 2004 and 2011. 1,158 or 19% of those deaths were deemed to be caused by their cancer.
Of the other 17,060 patients who were diagnosed with colorectal cancer but did not regularly receive aspirin 7,128 or 42.3% died in the seven-year time period. 5,375 or 31.5% of those deaths were caused by cancer.
To better understand the association between aspirin use and death from colorectal cancer, researchers used a type of statistical analysis called a multivariable Cox proportional hazard model. This type of statistical analysis allows researchers to study how a single variable, aspirin use in this case, affects survival while other factors such as age, severity/stage of cancer, and other illnesses which might also impact survival are controlled for.
Researchers found that aspirin use after diagnosis of colorectal cancer was statistically and significantly associated with both cancer-specific survival and overall survival. Specifically, cancer patients who did not take aspirin were 9.5 times less likely to survive the study’s seven-year time frame (for any reason: old age, accident, cancer or other illnesses), and 8.85 times less likely to survive because of their cancer.
The researchers concluded that of all the factors included in statistical analysis, “aspirin use was the strongest predictor” of mortality in this study population of 23,162 patients with colorectal cancer. The researchers also warned that aspirin may not be the best choice as a primary prevention, meaning aspirin should not be taken by every person to prevent colorectal cancer. Although widely available and commonly prescribed, aspirin is still a powerful drug that can cause rash, stomach ulcers, bleeding and nausea. The researchers suggest that aspirin should be a secondary prevention, meaning once a patient is diagnosed with colorectal cancer they may begin taking aspirin as long as the patient is otherwise healthy and not taking other medications that may interfere with the aspirin.
While their work may not find its way to as many headlines as immunotherapy and bioelectronic medicine, it has important implications none the less. Aspirin is an inexpensive, widely-available treatment option. While most chemotherapy drugs cost thousands of dollars a year and immunotherapy regimens costs hundreds of thousands, if not millions, of dollars a year, one Aspirin tablet costs $0.29 or €0.26 in Japan where aspirin is most expensive. In the United States, where cancer drugs are the most expensive of any country worldwide, one aspirin tablet costs $0.10 or €0.09.
Global prices of aspirin, Credit: http://www.statista.com/statistics/269944/aspirin-tablet-price-in-selected-countries/
Moreover, aspirin is a well-studied drug and has been used as a medical treatment for more than 100 years. That means the side effects are understood, predictable even, and the dosing regimens are well established.
The researchers admit that the molecular mechanisms underlying Aspirin’s involvement in cancer are not fully understood. Regardless, their study shows that Aspirin as a cancer treatment is a reasonable avenue of study and should be pursued further in randomized, placebo-controlled clinical trials for colorectal cancer and other cancer types.
- 2016 May 31. doi: 10.1200/JCO.2015.65.3519 http://jco.ascopubs.org/content/early/2016/05/25/JCO.2015.65.3519.full
- Side effects of aspirin: http://www.rxlist.com/aspirin-side-effects-drug-center.htm
- Global Prices of aspirin: http://www.statista.com/statistics/269944/aspirin-tablet-price-in-selected-countries/
- Global prices of other cancer drugs: http://www.oncologypractice.com/news/what-s-news/single-article/cancer-drugs-most-affordable-in-australia-least-in-india-and-china/96c8c48cc143618d6b3d9ddda08ca27a.html
- History of aspirin use: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1119266/
Credit: Jess Craig, @jessnicolecraig
Picture Credit: http://www.starrfmonline.com/1.8415188