Researchers have discovered that aspirin prevents blood platelets from producing an enzyme that allows them to clump together and regular, long-term use of low-dose aspirin may reduce the risk of death from colon and rectal cancers. Tumour cells can attach to these clumps and spread (metastasize) throughout the body. The findings were recently published in the Journal of the National Cancer Institute.
Colon and rectal cancers are the third-leading cause of US cancer deaths, contributing to an estimated 53,000 deaths last year. About 104,600 cases of colon cancer and 43,300 cases of rectal cancer were diagnosed in the US last year, according to the American Cancer Society.
"Aspirin inhibits platelet activation, which also could inhibit metastases," said lead author, Dr Jane Figueiredo, director of Community and Population Health Research at the Samuel Oschin Cancer Institute at Cedars-Sinai Medical Center in Los Angeles.
The use of non-aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, acetaminophen and naproxen was not associated with better outcomes.
For the study, Figueiredo's team analysed data from more than 2,500 colon and rectal cancer patients in the US.Timing of the aspirin use appears to be critical, according to the study. Patients who used it for at least 15 months before being diagnosed with localized colon or rectal cancer were less likely to see their tumour spread.
"More evidence is needed, but this association between baby aspirin and lower death rates is highly significant," added Figueiredo.
At the same time, while patients who began taking aspirin after their cancer diagnosis had better outcomes than those who did not take aspirin, the difference was not significant, the study found.
"These findings may provide an inexpensive lifestyle option to people seeking to prevent colorectal cancer, or to improve their prognoses if they are diagnosed.”
She noted that ongoing clinical trials are examining how aspirin use before and after a diagnosis of colon or rectal cancer affects survival.
"We have to wait until those results come out. There are potential harms associated with aspirin use." Daily use may increase the risk of allergic reactions and internal bleeding. There really needs to be a conversation between clinicians and patients about both the risks and benefits,” concluded Figueiredo said. "These studies and our results really add to that conversation."