A new study published in the journal CANCER has shed light on how long-term daily use of aspirin can help prevent the development and progression of colorectal cancer. The research, conducted by investigators in Italy, suggests that aspirin may exert these protective effects by enhancing certain aspects of the body’s immune response against cancer cells.
The study analyzed tissue samples from 238 patients who underwent surgery for colorectal cancer between 2015 and 2019, with 12% of the patients being aspirin users. Compared to non-aspirin users, tissue samples from aspirin users showed less cancer spread to the lymph nodes and higher infiltration of immune cells into tumors.
Aspirin Exposure Increases CD80 Protein Expression on Immune Cells
Laboratory analyses of colorectal cancer cells revealed that exposing the cells to aspirin caused increased expression of a protein called CD80 on certain immune cells. This increased expression enhanced the capacity of the cells to alert other immune cells of the presence of tumor-associated proteins. The researchers also found that in patients with rectal cancer, aspirin users had higher CD80 expression in healthy rectal tissue, indicating a pro-immune surveillance effect of aspirin.
Ensuring Adequate Aspirin Concentration in the Colorectal Tract
Principal investigator Marco Scarpa MD, PhD, of the University of Padova, emphasized the importance of ensuring that aspirin reaches the colorectal tract in adequate doses to be effective. “Aspirin is absorbed in the colon by passive diffusion to a significant degree. Its absorption is linear and depends on concentration along the bowel, and in the rectum, the concentration of orally administered aspirin can be much lower than in the rest of the colon,” he explained.
The study, funded by the Associazione Italiana per la Ricerca sul Cancro (AIRC) and mainly carried out at the University Hospital of Padova, highlights a complementary mechanism of cancer prevention or therapy with aspirin beyond its classical drug mechanism involving the inhibition of inflammation.