There is substantial evidence that a daily aspirin can reduce risk of colorectal cancer in adults up to age 70. An a large data analysis found such aspirin use was linked to lower colorectal cancer risk among people aged 70 or older. but only among those who started the regime before the age of 70, writes MedicalBrief.
The study, published in JAMA Oncology, was led by Dr Andrew T Chan, a gastroenterologist and chief of the clinical and translational epidemiology unit at Massachusetts General Hospital (MGH).
Findings In this pooled analysis of 2 cohort studies with a total of 94 540 participants, regular use of aspirin at or after age 70 years was associated with a lower risk of colorectal cancer compared with nonregular use. However, this reduction in risk was evident only among individuals who initiated use at a younger age.
Meaning These results suggest that the initiation of aspirin use at an older age for the sole purpose of primary prevention of colorectal cancer should be discouraged; however, the findings support recommendations to continue using aspirin if initiated at a younger age.
The researchers carried out a pooled analysis of two large US cohort studies: The Nurses' Health Study (January 1980 – June 2014) and the Health Professionals Follow-up Study (January 1986 – January 2014). These two studies contributed data on more than 94,500 participants' use of aspirin over about 35 years, offering a unique opportunity to understand the effect of aspirin use across the lifespan on cancer risk.
The researchers found that regular aspirin use was linked to lower colorectal cancer risk among people aged 70 or older. However, this advantage was only significant among people who started taking aspirin before the age of 70. People who started regular aspirin use at the age of 70 or older did not seem to reap any benefit.
"There is considerable evidence that aspirin can prevent colorectal cancer in adults between 50 and 70 years old," says Chan. "But it has not been clear whether the effect is similar in older adults."
Aspirin is considered the most well-established agent that protects against colorectal cancer (CRC). It is currently recommended by the US Preventive Services Task Force for people aged 50-59 years with specific cardiovascular risk profiles because of its protective effect against heart disease.
However, the recent Aspirin in Reducing Events in the Elderly (ASPREE) trial reported that participants who took a daily low dose of aspirin (100 mg) after age 70 for about five years actually had an unexpected 30% higher risk of death from cancer. The vast majority of the ASPREE participants (89%) had never taken aspirin regularly before joining the study. Chan's team also recently reported that ASPREE participants on aspirin did not experience an increase or decrease in risk of developing a cancer despite having an increase in risk of death from cancer.
That led to the question: Does regular aspirin benefit or harm people older than 70 and does it matter when aspirin was started?
The current study confirms that initiating aspirin at an older age was not associated with a lower risk of colorectal cancer. However, importantly, there is a potential benefit of continuing aspirin if is started at an earlier age. These results, the researchers say, "strongly suggest that there is a potential biological difference in the effect of aspirin at older ages which requires further research."
Adds Chan: "As people get older, if they are not already taking aspirin, a discussion is warranted about whether to start aspirin after weighing the benefits against the risks."
Aspirin Use and Risk of Colorectal Cancer Among Older Adults
Chuan-Guo Guo, Wenjie Ma, David A Drew, Yin Cao, Long H Nguyen, Amit D Joshi, Kimmie Ng, Shuji Ogino, Jeffrey A Meyerhardt, Mingyang Song, Wai K Leung, Edward L Giovannucci, Andrew T Chan
Published in JAMA Oncology on 21 January 2021
Although aspirin is recommended for the prevention of colorectal cancer (CRC) among adults aged 50 to 59 years, recent data from a randomized clinical trial suggest a lack of benefit and even possible harm among older adults.
To examine the association between aspirin use and the risk of incident CRC among older adults.
Design, Setting, and Participants
A pooled analysis was conducted of 2 large US cohort studies, the Nurses’ Health Study (June 1, 1980–June 30, 2014) and Health Professionals Follow-up Study (January 1, 1986–January 31, 2014). A total of 94 540 participants aged 70 years or older were included and followed up to June 30, 2014, for women or January 31, 2014, for men. Participants with a diagnosis of any cancer, except nonmelanoma skin cancer, or inflammatory bowel disease were excluded. Statistical analyses were conducted from December 2019 to October 2020.
Main Outcomes and Measures
Cox proportional hazards models were used to calculate multivariable adjusted hazard ratios (HRs) and 95% CIs for incident CRC.
Among the 94 540 participants (mean [SD] age, 76.4 [4.9] years for women, 77.7 [5.6] years for men; 67 223 women [71.1%]; 65 259 White women [97.1%], 24 915 White men [96.0%]) aged 70 years or older, 1431 incident cases of CRC were documented over 996 463 person-years of follow-up. After adjustment for other risk factors, regular use of aspirin was associated with a significantly lower risk of CRC at or after age 70 years compared with nonregular use (HR, 0.80; 95% CI, 0.72-0.90). However, the inverse association was evident only among aspirin users who initiated aspirin use before age 70 years (HR, 0.80; 95% CI, 0.67-0.95). In contrast, initiating aspirin use at or after 70 years was not significantly associated with a lower risk of CRC (HR, 0.92; 95% CI, 0.76-1.11).
Conclusions and Relevance
Initiating aspirin at an older age was not associated with a lower risk of CRC in this pooled analysis of 2 cohort studies. In contrast, those who used aspirin before age 70 years and continued into their 70s or later had a reduced risk of CRC.
Full text in JAMA Oncology (Subscription required)