The author Isabel Duarte resumes the comparison between cancer and Alzheimer's disease that she had established in a previous column. This time, however, the connection between the two diseases proves more peculiar: for decades, several studies have suggested that cancer and Alzheimer's disease seem to mutually avoid each other, with people who had cancer showing, on average, a lower probability of developing Alzheimer's. A meta-analysis published in 2020 estimated this reduction at approximately 11%.
A study published this year in the journal Cell suggests that this relationship may have a biological explanation. Researchers implanted human lung, prostate, and colon tumors in mice used as a model for Alzheimer's disease. The result was unexpected: the animals with tumors developed fewer amyloid-beta plaques in the brain and performed better on cognitive tests.
The researchers identified a protein called Cystatin C, produced by the tumors, which was able to reach the brain and stimulate natural mechanisms for removing amyloid-beta through microglial activation, cells that function as the brain's cleaning and surveillance service.
The author warns that the study was conducted in mice and it is not yet known if the same happens in humans. Furthermore, Alzheimer's disease is much more complex than amyloid-beta accumulation. Still, the interest lies in discovering which biological mechanism the tumor is exploiting and whether it is possible to reproduce it safely, exemplifying how a clue to understanding one disease can appear when studying another.
