Can an aspirin a day keep cancer away?
(CNN) — Aspirin is recognized for its effects in heart-attack prevention. And several studies “have provided evidence that nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, may hold promise in helping to prevent cancer,” according to the National Cancer Institute.
There’s a long history of research on aspirin and cancer, starting in the early 1990s. But can an aspirin a day keep cancer away?
It’s not quite that simple, although two studies published in the Lancet and one in Lancet Oncology suggest that aspirin could have some protective effects against cancer.
All three studies were conducted by Dr. Peter M. Rothwell and his colleagues at the University of Oxford and John Radcliffe Hospital, Oxford, United Kingdom.
In the first study published in the Lancet, the researchers found that the aspirin users had reduced cancer deaths (562 to 664 deaths) and fewer nonvascular deaths (1,021 to 1,173 deaths) – these are causes unrelated to the heart or circulatory system. These findings were based on 34 studies.
In 51 trials, aspirin users had lower nonvascular deaths and had reduced in-trial cancer deaths by nearly 40% after about five years.
The findings only applied to daily users of aspirin, not studies in which subjects consumed aspirin every other day.
In six prevention trials, aspirin users had reduced cancer incidence from three years onward by 324 cases compared with 421 cases in the groups who did not consume aspirin.
Rothwell and his colleagues wrote that the results in the short-term reductions in cancer incidence and mortality “add to the case for daily aspirin in prevention of cancer.”
Eric Jacobs, director of pharmacoepidemiology for the American Cancer Society, said it would take time for the scientific community to evaluate these new findings with existing evidence.
Using aspirin to help cancer prevention is not necessarily a new concept; previous studies have shown evidence it is particularly helpful in colorectal cancers.
“It is not entirely clear how aspirin works to prevent colorectal cancer and possibly other cancers,” Jacobs said. “These recent studies are finding apparent effects at very low doses that suggest the effects of aspirin on platelets may be important for cancer. Platelets are affected by very low doses of aspirin.”
Although daily aspirin has some promising benefits, it can also raise the risk of gastrointestinal bleeding.
Even low doses of aspirin can increase risk of stomach bleeding,” Jacobs said. “Low doses can help prevent heart attacks because they stop the platelets from sticking together and causing clots. They can, even in low doses, increase the risk of bleeding.”
Before popping aspirin for the sake of cancer prevention, Jacobs warned that a person should consult his or her doctors.
“It’s a balance of the overall risk and overall benefits,” he said.
The second article published in the Lancet indicated that aspirin could affect how cancer grows and spreads. The authors collected data from five studies totaling 17,285 patients in the United Kingdom.
The people in the experiment group took daily aspirin (less than 75 mg). The study found the aspirin reduced risk in cancers in the colon, lung and prostate by 46%, and other cancers, such as those in the bladder and kidney, by 18%.
“Allocation to aspirin reduced the incidence of new cancers during the trials,” wrote the researchers.
The third study published in Lancet Oncology observed the same effect from aspirin when the authors examined observational studies instead of trials. The results of the observational studies were 38% reduced risk of colorectal cancer among aspirin users.
In an accompanying commentary entitled, “Are we ready to recommend aspirin for cancer prevention?” two doctors commenting on the study wrote: “This finding was the first convincing evidence that aspirin might prevent death from several cancers, thereby widening its potential population-wide effect.”
But they wrote that the Rothwell studies didn’t include the trials in which subjects took aspirin every other day.
“Despite a convincing case that the vascular and anticancer benefits of aspirin outweigh the harms of major extracranial bleeding, these analyses do not account for less serious adverse effects on quality of life, such as less severe bleeding.”