A study in Gastroenterology found that regular aspirin use is associated with reduced colorectal cancer risk — however, this risk differed by concentration of tumor-infiltrating lymphocytes.
The researchers used data from prospective cohort studies to identify 1,458 rectal and colon cancer cases. They investigated how the degree of lymphocytic infiltrates in tumors affected the impact of aspirin use on colorectal cancer risk.
Here's what you need to know:
1. Regular aspirin use was associated with a lower risk of tumors that had low concentrations of tumor-infiltrating lymphocytes.
2. Regular aspirin use was not associated with a lower risk of tumors that had intermediate or high levels of tumor-infiltrating lymphocytes.
3. This observations — that aspirin impacted tumors with low concentrations of tumor-infiltrating lymphocytes, but not tumors with intermediate or high concentrations — remained, regardless of tumor microsatellite instability, mutations in BRAF, or expression of PTGS2.
The researchers concluded that these findings suggest the "immune response in the tumor microenvironment could be involved in the chemopreventive effects of aspirin."