Doctors have appreciated the healing potential of aspirin for centuries. Its longevity and versatility as a pain reliever and anti-inflammatory have led some to herald it as a "wonder drug." Aspirin is used to relieve headaches and arthritis. It helps reduce fevers and soothe toothaches. Because aspirin thins the blood, doctors may recommend it to some patients to help prevent blood clots and reduce the risk of a stroke or heart attack. Now, evidence is mounting that an aspirin regimen may also help reduce the risk of certain cancers, especially colorectal cancer. "Recent studies showed the use of aspirin for six years or longer yielded a decreased risk of colorectal cancer and other types of gastrointestinal cancer," says Dr. Jeffrey Weber, Gastroenterologist and Chief of Medicine at our hospital near Phoenix. "Studies have also shown that aspirin may reduce the incidence of polyps as well as advanced polyps."
So how may a pill you take to relieve a headache also help reduce your cancer risk? Aspirin, which is made of acetylsalicylic acid, is a nonsteroidal anti-inflammatory drug, a class of medications used to reduce pain and inflammation. These drugs work by targeting enzymes known as cyclooxygenases (COX). Two types of this enzyme—COX1 and COX2—help produce substances in the body that contribute to inflammation, a common response to injury or illness. When inflammation becomes chronic, it may cause DNA damage in cells in the inflamed area, which in turn may lead to serious diseases, such as colitis or cancer. "It is believed that prolonged inflammation can cause changes in cells, which may influence their tendency to become malignant," Dr. Weber says. "This appears to be especially true regarding the formation of colon polyps and colon cancer." Long-term aspirin use may reduce the inflammation that sometimes leads to cancer. Research also shows aspirin may help limit the production of a gene called c-Myc, a "master regulator" protein that helps control cell growth and division. The c-Myc protein is considered an oncogene, which has the potential to mutate a healthy cell into a cancer cell.
In a 2016 report published in the Journal of the American Medical Association, researchers who studied aspirin use in 135,000 patients concluded "long-term aspirin use was associated with a modest but significantly reduced risk for overall cancer, especially gastrointestinal tract tumors. Regular aspirin use may prevent a substantial proportion of colorectal cancers." Two studies in 2011 also concluded aspirin may help reduce cancer risk. One of those studies, of patients with Lynch syndrome, an inherited condition that increases the risk of colorectal cancer, concluded that an aspirin regimen "substantially reduced cancer incidence … in carriers of hereditary colorectal cancer." The other, a review of several studies involving more than 660,000 men and women, found "clear evidence that aspirin in doses as low as 325 mg per day reduces [colorectal cancer] risk." The U.S. Preventive Services Task Force recommends certain adults ages 50 to 59 years old take low-dose aspirin to help prevent colorectal cancer and suggests older adults also consider an aspirin regimen.
But before taking aspirin daily, consult your doctor. Aspirin is a powerful acid, and patients taking daily doses may develop side effects. "Aspirin use on a daily basis is not without significant risk," Dr. Weber says. "Primarily, the risks center on the gastrointestinal tract, where aspirin may cause ulcerations in the stomach, bowel and colon. In addition, aspirin will enhance bleeding, putting people at risk for gastrointestinal bleeding or bleeding from trauma, especially head trauma." Experts also urge parents not to give aspirin to children, and they warn nursing mothers that the drug may be passed onto babies through breast milk.
Still, experts believe taking aspirin daily may have many benefits for some people. The American Heart Association recommends that those at high risk of a heart attack talk to their doctor about taking low-dose aspirin to help reduce the risk of blood clots that may lead to a heart attack or stroke. And University of Southern California researchers tout aspirin as an inexpensive option that may prevent heart disease and certain cancers. "As the U.S. works to advance the triple aim of better care, better health, and smarter spending, ensuring patients receive effective preventive care will be critical," the researchers say in an article on their findings. "Given aspirin's remarkable preventive effectiveness, it is a rare example of a technology that may produce less disease and better long-term health outcomes for Americans at a low price."
Learn more about treatments for colorectal cancer.