Low-Dose Aspirin May Cut Risk Of Developing And Dying From Colon Cancer
Pooled analysis of five trials with a 20-year study show that low doses of aspirin may reduce the risk of developing and dying from colon cancer, the second most common cancer in developed countries after lung cancer.
Researchers have found that it reduces the incidence of colon cancer by 24 percent and mortality by 35 percent.
They said their findings could tip the scales in favor of using aspirin to prevent colon cancer, according to Reuters.
Peter Rothwell, professor of clinical neurology at Oxford University and Oxford John Radcliffe Hospital, both in the UK, and colleagues presented the results of his analysis in the 22 October issue of The Lancet.
Colorectal cancer has a lifetime risk of 5%, each year about 1 million people are discovering that they have the disease and 600.000 die from it.
In their analysis, Rothwell and colleagues analyzed five combined randomized trials assessing the impact of aspirin on incidence and mortality from colorectal cancer, paying particular attention to dose, duration of treatment and the tumor.
Previous studies have shown that high doses of aspirin (500 mg or more per day) reduces the long-term incidence of colorectal cancer, but the risk of side effects such as gastrointestinal bleeding, "may limit their potential for long-term prevention," the authors write.
For the study, Rothwell and colleagues observed the five trials (done in the UK, Sweden and Holland), who were primarily interested in the effects of aspirin on cardiovascular outcomes, but they were able to monitor colorectal cancer incidence and mortality from cancer registries and certificates death.
They then combined individual patient data and analyze the effect of doses below 75 mg / day of aspirin on the risk of colorectal cancer in 20 years during and after the test.
The results showed that: in the four trials of aspirin versus control (average treatment duration was planned 6 years), 2.8 percent of more than 14,000 patients for colorectal cancer during the median follow-up of 18.3 years. Those on aspirin were 24 percent lower risk of colon cancer (relative risk of disease HR = 0,76, 95% confidence interval, CI = 0,60 - 0,96, p = 0.02) and the risk of death also declined by 35 percent (0.65, 0.48-0.88, 0.005). However, colon cancer did not show such a drop (0.90,0.06-1.30, 0.58 in fall and 0.80, 0.50-1.28, 0.35 for mortality). Where the tumor site data were available, it was found that aspirin reduced the risk of proximal colon cancer, but not distal colon. Allowance increased from the planned duration of treatment, such that, while on aspirin for 5 years or more reduces the risk of proximal colon cancer by about 70 percent, and reduced risk of rectal cancer. There was no benefit in increasing the dose above 75 mg per day. In a Dutch trial that tested various doses, the risk of fatal colon cancer was higher than 30 mg per day than 283 mg per day that. The authors concluded:
"Aspirin is taken within a few years at doses of at least 75 mg per day lowered the long-term morbidity and mortality from colorectal cancer."
"Benefit was greatest for proximal colon cancer, which are not other reasons can not effectively screening with sigmoidoscopy or colonoscopy," they said.
This news will likely have a mixed reception. Some doctors may be reluctant to encourage aspirin route as a way to prevent colon cancer because of the associated risks, while others may be involved in a relatively cheap alternative that offers the drug, especially if they sympathize with patients who want to avoid discomfort and embarrassment of the invasive tests.
In an accompanying editorial, Dr. Robert Benamouzig and Bernard Uzzan, from Avicenne Hospital in Bobigny, France, said the study had limitations in that the cancer was not the primary outcome studied in the trials, and there was not enough data on the aspirin-related deaths with.
In addition, patients were mostly men with cardiovascular risk, so the results can not be generalized to other populations such as women and people without these risks.
However, they said the study was very "interesting", especially in patients at high risk.
"Long-term effect of aspirin on the incidence of colorectal cancer and mortality: a 20-year follow-up of five randomized trials." Peter M Rothwell, Michael Wilson, Carl-Erik Elwin Bo Norrving, Ale Algra, Charles P Warlow, Tom Mead Tues Lancet, 22 October 2010 DOI: 10.1016/S0140-6736 (10) 61543-7