Taking a low dose of aspirin every day could have the potential to prevent breast cancer or stop it in its tracks.
That was the news over the weekend from the annual meeting of the American Society for Biochemistry and Molecular Biology in Boston, where a team of researchers from the Veterans Affairs Medical Center in Kansas City and the University of Kansas Medical Center presented evidence demonstrating the effects of aspirin against two types of breast cancer.
One of them, so-called "triple negative" cancer, is the most aggressive type of breast cancer and also the most dangerous because it often doesn't respond to conventional therapies.
Last year, another study also conducted at the University of Dundee in Scotland found similar results in 116, 181 women who take aspirin regularly. A 30-percent lower risk of breast cancer was found in women who took aspirin for three to five years and a 40 percent risk reduction was found after more than five years of aspirin use.
Breast cancer is just one of many types of cancer that are being studied in relation to the lowly painkiller. Previous research has shown the potential of low-dose aspirin to:
- prevent prostate cancer
- reduce the risk of esophageal cancer, and prevent Barrett's esophagus, a condition that ups the risk of cancer
- improve survival of those with colon cancer
- lowers risk of skin cancer
- prevent early stage cancers from metastasizing, or spreading to distant parts of the body
The most exciting research on the aspirin-cancer connection came last year, when three related studies were published simultaneously in The Lancet and The Lancet Oncology. The first of the studies looked at aspirin and the likelihood of dying from cancer. Analyzing the data from 51 randomized trials, the authors found that aspirin reduced death from cancer by 15 percent and that the benefit increased over time, rising to 37 percent after five years.
The second study looked at the effect of aspirin on cancer metastases and found that aspirin appeared to reduce the risk of cancer spreading by 36 percent over 6.5 years. A third study was an analysis of data from a number of studies that followed people over time, and the results of this study appeared to confirm the other two.
At the time, Peter Rothwell of Oxford University, the lead researcher on the studies and one of the world's leading experts on aspirin and cancer, summed up his conclusions by saying: "Aspirin reduces the likelihood that cancers will spread to distant organs by about 40-50 percent."
How Does It Work (If It Works)?
There are two explanations offered for aspirin's possible cancer-protective effects. One is that its anti-inflammatory action prevents the inflammation that's thought to trigger or boost the growth of cancerous cells.
But some studies, including yesterday's breast cancer news, suggest that aspirin's target is cancer stem cells, the stubborn cells at the root of tumor growth and metastasis.
The lead researcher for the new breast cancer studies, Sushanta Banerjee, director of the cancer research unit at the University of Kansas, noted that chemotherapy for breast cancer does not necessarily kill stem cells, which will restart tumor growth if they survive.
The research so far suggests that aspirin is more effective against one type of cancer, adenocarcinomas, than against other types. Most colorectal, esophageal, prostate and breast, and some lung cancers are adenocarcinomas.
Aspirin-Cancer Connection Research Still In Early Stage, Experts Caution
Like most of the aspirin and cancer studies to date, yesterday's breast cancer research was of the preliminary type, in this case a test tube study using cancer cell lines and further testing in mice. However, it's exciting in the way that it extends the knowledge gained from previous aspirin and cancer studies.
Scientists have been exploring the possiblity that regular aspirin use is protective against cancer for more than 20 years. But very few of these studies have been "gold standard" double-blind placebo-controlled human trials.
And not all the research on aspirin and cancer has been positive. In 2005, results of a large 10-year double-blinded placebo-controlled trial found that low-dose aspirin had no effect on cancer incidence or death rate. However, the dosage was very low (100 mg) and the women took aspirin every other day rather than every day. At the time, the researchers concluded that further trials were needed.
How Long Does It Take to Work?
Well, that's one of the problems of aspirin therapy - you have to be patient and consistent. Eight years was the amount of time previously indicated before aspirin therapy's benefits could be felt. However, the studies in The Lancet found that aspirin therapy becomes effective in two to three years rather than eight.
Risks of Aspirin Therapy
The primary reason experts are cautious about using aspirin for cancer prevention is that it does have a fairly common side effect of irritation, ulceration, and bleeding in the stomach and digestive tract.
Other studies of the health benefits of aspirin have concluded that while it's effective in reducing the risk of serious conditions, it also ups the risk of internal bleeding and therefore isn't worth it for those who aren't sick. In 2012, researchers at the University of London looked at nine clinical trials involving a total of 100,000 healthy, middle aged patients and found that aspirin upped their risk of internal bleeding by 30 percent.
However, some of the cancer researchers conducting aspirin research, most notably Peter Northwell, have begun to point out that while aspirin's gastric and bleeding effects occur in significant numbers of people,they're not usually life threatening, which cancer, of course, is.
Going Forwards? A Cautious Approach
Acceptance of aspirin therapy for cancer has been slow, with experts waiting for more human clinical trials. The National Cancer Institute has a topic center on aspirin and cancer prevention that summarizes numerous studies with the commentary that aspirin and other NSAIDs "may hold promise" in helping prevent cancer.
If you're tempted to self-treat, don't - discuss it with your doctor first. If you get the okay, stick with low-dose or "baby" aspirin, which contain 81 mg. Regular full-dose aspirin tablets contain 325 mg each. And of course you always want buffered or "enteric-coated" aspirin to protect your digestive tract.
In the end, it's probably going to be an individual risk-vs-benefit equation for each of us, based on our risk of cancer and heart disease, how old we are, and how strong our stomachs are. And, of course, what our doctors think. I'm guessing that for cancer survivors concerned about recurrence, or those with early stage cancers with the possibility for metastases, the decision to include aspirin in their treatment regimen is going to be clearer.
