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Aspirin may help some people with colon cancer live longer, according to a new study.
Researchers looked at nearly 1,000 patients with colon cancer, and tracked them for between four and 10 years. They found 37.9 percent of those who regularly took aspirin died, compared with 48.5 percent of the patients who didn't take aspirin.
However, the benefit of taking aspirin was seen only in patients whose tumors made a certain protein, called HLA class I antigen. This protein may be involved in the immune system's response to cancer cells, the researchers said, although more research is needed to understand the mechanism.
"If our results are confirmed by others and aspirin is studied as a treatment in a proper phase three randomized trial, then we would have a valid new anti-cancer treatment that is both safe and cheap," said study author Gerrit Jan Liefers of Leiden University Medical Center in the Netherlands.
"In a world were new targeted therapies usually cost thousands of dollars and most have serious side effects, this would mean great progress," Liefers told Live Science. [Aspirin to Zoloft: The Scoop on 5 Medicines]
Colon cancer is the fourth most common cancer in the United States, but ranks second in number of yearly deaths (behind lung cancer). In 2013, about 143,000 people in the U.S. were diagnosed with colon cancer, and about 51,000 died from the disease, according to estimates from the National Cancer Institute.
In the study, the researchers analyzed tissue from tumors from 999 colon cancer patients who had undergone surgery between 2002 and 2008. Among the patients, 182 were aspirin users, and 69 of these patients died by January 2012. On the other hand, 396 of the 817 patients who didn't take aspirin died.
How aspirin may work to lengthen life in people with colon cancer is not clear, according to the researchers. For now, they speculate that aspirin may affect the ability of tumor cells circulating in the body to develop into new cancer growths, or metastases.
The study does not prove that people with colon cancer should start taking aspirin, Liefers said.
"We have to await the results of a randomized trial before we can recommend aspirin as a valid anti-cancer treatment," he said.
Dr. Alfred Neugut, an oncologist at Columbia University who was not involved in the study, agreed that treatments should not change based on the new findings.
However, in oncology, there is a tendency "to await randomized data before creating a new standard of care," Neugut wrote in an editorial accompanying the new study in the journal, wondering if this process should always be essential.
"For my own patients, I have so far not recommended aspirin [for colon cancer]. But I think based on current evidence, that if I personally had a stage III tumor, I would add aspirin to my treatment," Neugut wrote.
Previous research has found a link between aspirin use and a lower risk of developing colon cancer.