Study: Body Mass Index (BMI) may affect how well aspirin use protects against colorectal and ovarian cancer

Contents

STUDY AT A GLANCE

What is this study about?

This study is about whether daily aspirin use is protective against colorectal, prostate, ovarian, endometrial and breast cancers, and the effect of cancer risk factors such as being overweight, smoking, and having a family history of cancer on this protection.

Why is this study important?

Several studies have consistently shown a link between daily aspirin use and reduced cancer risk, especially for colorectal cancer. The United States Preventive Services Task Force recommends daily low-dose aspirin to help prevent the onset of colorectal cancer in adults age 50 and older who are at increased risk for colorectal cancer and aren’t at risk for bleeding.

Researchers have looked at whether daily aspirin use lowers the risk for prostate, ovarian, endometrial and breast cancers. Research has not consistently shown that aspirin protects against these cancer types. In addition, how different major risk factors for cancer, such as elevated body mass index (BMI), older age, smoking, physical inactivity and familial history of cancer affect the actions of aspirin on risk is unknown. BMI is a measure of body fat based on height and weight in adults (BMI calculators like this one, use height and weight to estimate BMI). Research shows that a BMI of 25 kg/m2 or greater can lead to serious medical conditions such as metabolic syndrome, high blood pressure, atherosclerosis, heart disease, diabetes, high blood cholesterol, sleep disorders and cancers.

In this study, researchers wanted to know if these major risk factors impact aspirin’s ability to protect against cancer.

Study findings

Researchers examined the medical information of more than 423,000 individuals ranging from ages 50 to 74 who were a part of two national clinical trials in the United States. Each study participant provided information about their aspirin use within a given year, cancer diagnosis, age, BMI, smoking status, physical activity and a family history of cancer.

The primary goal of the study was to compare the incidence of colorectal, ovarian, breast, endometrial or advanced prostate cancers among “daily aspirin users” (those who took a daily aspirin at least five days per week) and individuals who took fewer than five aspirins or no aspirin per week. Incidents of cancer were further evaluated by the patients’ risk factors for cancer, such as age, BMI, smoking status, physical activity and a family history of cancer.

Study findings showed that:

• Daily aspirin use was associated with a 15% reduction in overall risk for colorectal cancer.
  • This protection was lost as participant BMI increased.
  • Other cancer risk factors, such as physical activity level and having a family history of cancer, did not impact the protective effect of aspirin against colorectal cancer.
• Overall, daily aspirin use offered little protection against ovarian cancer.
  • However, daily aspirin use was associated with a 28% reduction in ovarian cancer risk among women who were considered to be obese (with a BMI of 30 kg/m2 or greater).
• Daily aspirin use offered little or no protection against advanced prostate cancer, breast cancer or endometrial cancer.

Strengths and limitations

Strengths:

• The study was large, including the medical information of more than 423,000 patients from multiple study sites.
• The study took a broader look at whether aspirin use is associated with cancer prevention by examining its impact in the presence of major cancer risk factors, such as BMI, physical activity and a family history of cancer. The effectiveness of drugs, including aspirin, can have different outcomes based on these and other risk factors.
• The study confirmed the diagnosis of cancer through review of medical records, not just based on patient reporting.

Limitations:

• The study did not include data from people under the age of 50. This limits our ability to make conclusions about the benefits of aspirin in people of this age group.
• The study was not particularly diverse regarding race and ethnicity. Ninety percent of the study participants identified as White, whereas White people comprise about 70% of the U.S. population.
• Patient information concerning BMI, smoking and aspirin use was self-reported and not confirmed by medical records.

What does this mean for me?

In this study, daily aspirin use was linked with a reduction in the overall risk of colorectal cancer, however, this protection was lessened with increasing BMI.

For ovarian cancer, aspirin use was only protective in women with a BMI of 30 kg/m2 or greater. Because the study showed that aspirin protection can vary depending on individual cancer risk factors, it is important to talk to your doctor about measures that you can take to reduce your cancer risk.

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posted 3/19/21
 

References

• Hurwitz L, Michels K, Cook M, et al. Associations between daily aspirin use and cancer risk across strata of major cancer risk factors in two large U.S. cohorts. Cancer Causes Control; 2021; 32(1):57-65. Published online October 26, 2020. 
• Chubak J, Kamineni A, Buist D, et al. Aspirin Use for the Prevention of Colorectal Cancer: An Updated Systematic Evidence Review for the U.S. Preventive Services Task Force. Rockville (MD): Agency for Healthcare Research and Quality (US); 2015 Sep. (Evidence Syntheses, No. 133.)

Disclosure

FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board before publication to assure scientific integrity.