Introduction: Previous literature has reported ambiguous results regarding the association of severe psychiatric disorders and an increasing risk of cancer disease-The aim of our analysis was to explore any associations between SPD, like schizophrenia (SCZ), Bipolar Disorder (BD) and recurrent major depression (MDD), and cancer diseases by meta-analyzing Mendelian Randomization (MR) studies available in the current literature. Methods: The present systematic review and meta-analysis was registered in the Prospero register (id. no. CRD420251072022). The databases consulted were Embase, Scopus, PubMed, and Web of Science. This study considered only studies that used MR to explore the causal effects of MDD, SCZ, and BD on cancer outcomes and that included MR as part of their analysis in humans. Results: A total of 7 MDD studies were selected for quantitative analysis. The findings of this study highlighted a statistically significant association between cancer and SCZ using the IVW method (OR = 1.05; 95% CI: 1.004; 1.105; P P= 0.032). Conversely, using the other two MR methods (MR-Egger and MR-Weighted Median) yielded no significant association, also in SCZ. Discussion: Literature on this topic remains scarce, and more studies are needed to assess the association between SPD and cancer. Conclusion: The need to improve health management strategies for individuals with SPDs remains unmet. Further investigation into biological functions and interdisciplinary associations will inform future interventions and public health policies to moderate cancer risk in this susceptible population.
Vitale et al. (Wed,) studied this question.