Meta-analysis reveals an inverse relationship between Alzheimer's disease and cancer

Recent reports have suggested an inverse relationship between Alzheimer's disease (AD) and cancer, although the underlying mechanism remains unclear. We performed an epidemiological meta-analysis to assess cancer likelihood in AD patients and vice versa and explored the role of APOE in tumor immunity across 33 The Cancer Genome Atlas (TCGA) cancer types. Our analysis revealed that people with AD are epidemiologically less likely to develop cancer than individuals without AD (RR: 0.53), and cancer patients are less likely to develop AD than non-cancer patients (RR: 0.61). Notably, APOE expression was positively associated with anti-tumor immune signatures and prevalent in early-stage tumors. This research reveals that AD patients are less likely to develop cancer and vice versa, pinpoints APOE gene as a risk factor for AD with anti-tumor activity, and provides new insight into the epidemiologically observed inverse relationship between both diseases.