Aspirin only reduces the risk of colorectal cancer in adults if it is started before age 70.

Specifically, until now, there was clear scientific evidence that one aspirin a day could reduce cancer in adults up to the age of 70, but it was not known whether adults over 70 should take these aspirin.

Regarding the benefits demonstrated in previous studies on the consumption of daily aspirin to reduce colorectal cancer in adults, a group of scientists from Massachusetts (United States) has investigated up to what age this practice is effective, discovering that, if you start After age 70, taking aspirin regularly is of no use in this regard.

Thus, these researchers, led by gastroenterologist and head of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital, Dr. Andrew T. Chan, knew that regular aspirin consumption was good for reducing the incidence of colorectal cancer in adults. middle-aged, but they wanted to investigate at what age these adults should start taking this drug regularly and for how long for it to have this effect.

Specifically, until now, there was clear scientific evidence that one aspirin a day could reduce cancer in adults up to the age of 70, but it was not known whether adults over 70 should take these aspirin. "There is a lot of evidence that aspirin can prevent colorectal cancer in adults between 50 and 70 years old," Chan said. "However, it has not been clear whether the effect is similar in older adults," she adds.

That is why the researchers conducted a joint analysis of two large American cohort studies, the 'Nurses' Health Study' (January 1980 - June 2014) and the 'Health Professionals Follow-up Study' (January 1986 - January 2014). These two studies provided data on aspirin use by more than 94.500 participants over approximately 35 years, providing "a unique opportunity to understand the effect of lifelong aspirin use on risk of cancer", as summarized by the scientists.

Thus, researchers found that regular aspirin use was linked to a lower risk of colorectal cancer among people aged 70 and older. However, this advantage was only significant among people who had started taking aspirin before age 70. In contrast, people who had started taking aspirin regularly at that age did not appear to benefit from it.

In this sense, aspirin is considered to be the most established agent that protects against colorectal cancer. Currently, the United States Preventive Services Task Force recommends it for people ages 50 to 59 with specific cardiovascular risk profiles, due to its protective effect against heart disease.

Risk of death from cancer

However, the recent Aspirin in Reducing Events in the Elderly (ASPREE) trial concluded that participants who took a daily low dose of aspirin (100 milligrams) after age 70 for about five years actually had an unexpected risk of death from cancer 30 percent higher. The vast majority of ASPREE participants (89%) had never taken aspirin regularly before participating in the study.

Thus, Chan's team found that ASPREE participants who took aspirin did not experience an increased or decreased risk of developing cancer, despite having an increased risk of death from cancer. This led scientists to think that when you started taking aspirin on a regular basis really mattered.

In this sense, the current study confirms that starting aspirin consumption at an advanced age is not associated with a lower risk of colorectal cancer. However, the most important thing about this research is the demonstration that there is a potential benefit if it is started at an earlier age.

These results, the researchers say, "strongly suggest that there is a possible biological difference in the effect of aspirin at older ages that requires further investigation." For his part, Chan adds that, "as people age, if they are not already taking aspirin, a debate is warranted about whether to start taking it, after weighing the benefits against the risks, such as gastrointestinal bleeding." .