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ACS Research Highlights

Does Regular Use of Aspirin Improve Colorectal Cancer Survival?

Analysis of the ACS’s Cancer Prevention Study-II Nutrition Cohort shows how aspirin use affects the risk of developing colorectal cancer and dying from it.

The Challenge

Many studies have found that people who regularly take aspirin or another non-steroidal anti-inflammatory drug (NSAID), including ibuprofen (Advil, Motrin) and naproxen sodium (Aleve), have a lower risk for developing colorectal cancer (CRC) and polyps.

However, research results have been mixed about whether regularly taking aspirin or another NSAID helps improve the survival of people who have been diagnosed with CRC. And, not all people can safely take these medicines because of their potential for serious side effects.

Some earlier research suggested that people with CRC who took aspirin either lived just as long as those who didn’t take it, or lived a bit longer. However, a large clinical trial called the Aspirin in Reducing Events in the Elderly (ASPREE) study had different results.

The ASPREE trial compared people age 70 years or older who took a low-dose aspirin every day to those who took a placebo. The trial tracked them for an average of 4.7 years. The study authors reported unexpected, but statistically significant, results: the group that took the low-dose aspirin had more deaths from CRC during the years they were followed than those who took the placebo. 

Because of these conflicting studies, and because people with CRC seek guidance on what they can do to improve their prognosis, American Cancer Society (ACS) scientists were motivated to further study the use of aspirin.

The Research

Peter Campbell, PhD, and his colleagues were interested in seeing aspirin’s effects in a much larger study than ASPREE. They used the ACS’s Cancer Prevention Study-II (CPS-II) Nutrition Cohort to look at the use of aspirin and other types of NSAIDs before and after a diagnosis of CRC. They wanted to learn how aspirin might influence death from CRC for several years after diagnosis. Their results were published in JNCI: The Journal of the National Cancer Institute.

“We used responses from surveys in our CPS-II Nutrition Cohort to learn about long-term aspirin use both before and after a diagnosis of colon or rectal cancer. We found that those who reported taking aspirin at least 15 times a month before a diagnosis were less likely to die from colorectal cancer. So we looked at the data again to see if we could learn why. We found that people who regularly took aspirin before their diagnosis were less likely to have distant metastases.”Peter Campbell, MSc, PhD
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From the survey answers of men and women in the cohort who were diagnosed with CRC and could safely take aspirin, the study authors learned:

  • People who reported that they regularly took aspirin (more than 15 times a month for at least 2 or 3 years) before their diagnosis of nonmetastatic CRC were less likely to die from CRC than those who did not take aspirin before their diagnosis. This may be due, in part, to the way aspirin seems to limit metastasis of colorectal tumors.
  • People who reported they regularly took aspirin after they were diagnosed with CRC were no more or less likely to die from CRC than those who didn’t take aspirin or another NSAID. But the researchers did not find that there was any harm from taking an NSAID, as the ASPREE study reported.
  • The people who reported taking aspirin before a diagnosis of CRC were also less likely to have distant metastases when they were diagnosed.

Why It Matters

Altogether, this study suggests that for people who can safely take it, long-term, regular use of aspirin (for more than 2 years, taking 15 or more pills a month) before a diagnosis of CRC may be associated with a lower risk of being diagnosed with metastatic CRC. This finding is particularly important because treatment options are usually quite good for CRC that has not spread beyond the colorectum whereas treatment options are much less successful for CRC that has spread beyond the colon or rectal wall.

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