While prior data revealed day-to-day usage of aspirin is associated with an overall reduced rate in cancer mortality, more recent research demonstrated the association with a lower cancer mortality rate is a lot smaller than previously believed.

There are two types of aspirin usage. Prescribed aspirin is aimed to relieve symptoms such as rheumatoid arthritis, osteoarthritis and other conditions where the immune system attacks joints and organs causing swelling and pain. Non-prescription aspirin is used to reduce fever and to relieve mild to moderate pain, among a slew of other things.

According to a current pool of assessments of randomized trials, researchers observed the effects of the daily use of aspirin as a preventative measure for vascular events, there was a significant decrease in overall cancer mortality by 37 percent during a five-year follow-up and a 15 percent decrease during a 10-year follow-up. However, with such data, the long-term day-to-day use of aspirin on cancer mortality rate remains undetermined.

Eric J. Jacobs, PhD, of the Epidemiology Research Program at the American Cancer Society in Atlanta and colleagues observed data that consisted of 100,139 men and women from the Cancer Prevention Study II Nutrition Cohort. All individuals had no former history of cancer and had been taking their daily dose of aspirin. Researchers also used follow-up questionnaires to examine each participant's aspirin intake.

Data revealed that among the 5,138 participant who died from cancer, their daily aspirin usage was associated with a slightly lower cancer mortality rate although this effect had no connection to the length of daily intake by the participant.

The researchers stated, "Our results are consistent with an association between recent daily aspirin use and modestly lower cancer mortality. However, the estimated reduced risk of 16 percent was much lower than the 37 percent reduction seen during the five-year follow-up period in the pooled analysis." They continued, "Even a relatively modest benefit with respect to overall cancer mortality could still meaningfully influence the balances of risk and benefits of prophylactic aspirin use."

Jacobs and his team do advise that the study has its potential limitation, stating they could have underestimated or overestimated the size of reduction in cancer mortality rate.

The study was published in the Journal of the National Cancer Institute.