Regular Aspirin Use Associated With Lower Prostate Cancer Risk

A National Health Interview Survey found that regular aspirin use is significantly associated with lower self-reported prevalence of prostate cancer.

Although in prior studies aspirin was found to be associated with reduced carcinogenesis of prostate cells, it was unclear whether taking aspirin regularly would lower the risk of prostate cancer. To determine if there was an association, researchers from the National Center for Health Statistics used cross-sectional data from the 2010 National Health Interview Survey (NHIS) for their study.

Researchers used the Person file, Sample Adult file, and Cancer Control Supplement file of the NHIS, which included a total of 11,657 adult male respondents in the sample. The dependent variable of the study was self-reported prostate cancer prevalence measured using 2 consecutive questions in the Sample Adult file.

The first question was “Have you ever been told by a doctor or other health professional that you had cancer or a malignancy of any kind?” Those who responded yes were given the follow-up question: “What kind of cancer was it?”

The key independent variable was whether the respondents self-reported regularly taking aspirin. This was measured by the question: “Do you now take any of the following medications regularly, that is, at least 3 times a week? Aspirin, Bayer, Bufferin, or Excedrin?”

Since NSAID or COX-2 inhibitor use, dietary consumption, family history, smoking status, alcohol consumption, and exercise are associated with prostate cancer incidence, they were included as covariates.

In 2010, the estimated US male adult population was 106.6 million. The results of the study found that an estimated 2.5 million male respondents (2.3%) reported ever having had prostate cancer. For regular aspirin users, there was an estimated 23.4 million (23.7%) respondents.

Approximately 60.3% of the male respondents were between 20- and 49-years-old, and 69.1% were non-Hispanic white. The largest proportion of people lived in the Southern United States.

There were about 1.3% of males who regularly took finasteride, while 14.8% regularly took non-aspirin NSAIDs or COX-2 inhibitors.

There were 21.7% respondents who were current smokers, 52.5% were either never exercised or were unable to exercise, 34.4% engaged in regular exercise more than 3 times a week, about 90% never took calcium and vitamin D supplements, more than 70% did not receive a PSA test in the previous 5 years, and most reported being in more than good health status (87%).

Regarding US males with and without prostate cancer, researchers found that people who were older were more likely to have prostate cancer. Males who believed they had a higher risk of cancer were more likely to have prostate cancer (less likely: 1.7% vs about as likely: 1.9% vs more likely: 5.8%; P<0.01).

Males respondents who never able or currently unable to engage in vigorous physical activity were significantly more likely to have prostate cancer compared to males who engage in regular physical activity (never/unable: 3.0% vs less than once week: 1.3%, vs 2 times per week: 1.2%, vs over 3 times per week: 1.9%; P<0.01).

After adjusting for predisposing factors, the result of the first sensitivity analysis showed that regular aspirin use was associated with a lower self-reported prevalence of prostate cancer compared with individuals who did not use aspirin regularly. However, the findings were not statistically significant (odds ratio [OR] 0.95, 95% confidence interval [CI] 0.69—1.31).

The results of the second sensitivity analysis revealed that regular aspirin use was associated with a lower self-reported prevalence of prostate cancer compared with non-regular aspirin use, but the results were again found to not be statistically significant (OR 0.86, 95% CI 0.61—1.21). The findings from the main analysis revealed that regular aspirin use was significantly associated with a lower self-reported prevalence of prostate cancer compared with non-regular aspirin use (OR 0.60, 95% CI 0.38–0.94).

There was no significant association found between NSAID use and reduced prevalence of prostate cancer. Additionally, several covariates such as age, smoking status, family history, patient health belief, number of PSA tests in the past 5 years, and regular finasteride use were associated with a lower prevalence of prostate cancer.

Some limitations included: recall bias unable to be eliminated in the study; due to the nature of the study, only the association and not causality between the variable can be drawn from the findings; prevalence of prostate cancer was based on respondent self-report; inaccuracy of diagnosis due to the NHIS questionnaire design could threaten the validity; and for some questions researchers could not determine the rationale for self-reported answers.

Although the study results found that regular aspirin use was significantly associated with a lower self-reported prevalence of prostate cancer in the US male population in 2010, further researcher needs to be done. Researchers said a longitudinal study with a longer follow-up period and a detailed dosage and intake duration information is required.