The list of things that aspirin can do gets seemingly larger every year. Beyond its initial indication for the treatment of headaches and migraines, low-dose aspirin has been indicated, arguably, for patients to prevent cardiac episodes or the reoccurrence of cardiac issues in individuals who previously had a heart attack or mild stroke. Furthermore, previous studies have shown that acetylsalicylic acid (ASA), the chemical name for aspirin, blocks tumor growth in colon, gastrointestinal, and prostate cancers.
Now, researchers from the Cancer Research Unit at the Kansas City Veterans Affairs Medical Center want to add breast cancer to the ever expanding list of aspirin’s abilities. The scientists assert that the important part is to ensure that conditions around cancer stem cells are not conducive for reproduction—something aspirin seems able to pull off.
Many cancers have stem cells, or residual cells. These cells often survive chemotherapy or some other cancer treatment and go dormant until conditions within the body are more favorable for them to again reproduce.
“In cancer, when you treat the patient, initially the tumor will hopefully shrink,” stated Sushanta Banerjee, Ph.D., research director of the Cancer Research Unit at the Kansas VA Center. “The problem comes 5 or 10 years down the road when the disease relapses. When they reappear they can be very aggressive, nasty tumors.”
The findings from this study were published recently in Laboratory Investigations through an article entitled “Aspirin blocks growth of breast tumor cells and tumor-initiating cells and induces reprogramming factors of mesenchymal to epithelial transition.”
Initially, Dr. Banerjee and his team grew cancer cells in 96-well plates and exposed half of them to varying concentrations of ASA. The researchers observed that exposure to the drug dramatically increased the rate of cell death and for cells that did not die they were unable to grow any further.
With these results in tow, Dr. Banerjee’s team took 20 mice with aggressive tumors and gave half of them the human equivalent of 75 milligrams of ASA, the typical low-dose regimen concentration, for 15 days. When the tumors from all of the mice were weighed at the end of the study, the investigators found that the mice treated with aspirin had tumors that were almost 50% smaller than the untreated controls.
Additionally, the research team gave a group of mice aspirin for 10 days prior to exposing them to cancer cells. After 15 days of exposure to cancer cells the aspirin pretreated group had significantly less cancerous growth than the control group.
“We found aspirin caused these residual cancer cells to lose their self-renewal properties,” explained Dr. Banerjee. “Basically, they couldn't grow or reproduce. So there are two parts here. We could give aspirin after chemotherapy to prevent relapse and keep the pressure on, which we saw was effective in both the laboratory and the mouse model, and we could use it preventatively.”
Many experts would agree that patients should consult with their doctor before starting a daily aspirin regimen, as the drug has been known to have anticoagulant properties and may increase the risk of gastrointestinal bleeding.
“Of course there is a risk,” said Dr. Banerjee, “but you have to weigh that against the risks of cancer. It's true this is relatively new and we don't know all the side effects yet, but this was a very low dose.”