Double burden of cancer and bipolar disorder: Implications for mental health care

Table 2 Shared biological and treatment-related mechanisms linking bipolar disorder and cancer

Domain	Mechanism	Evidence in BD	Evidence in cancer	Clinical implications
Inflammation	Tumor necrosis factor alpha, interleukin-6 have increased	Acute episodes, early BD	Tumor progression, immune evasion	Mood destabilization, worse prognosis
Hypothalamic-pituitary-adrenal axis	Cortisol dysregulation	Flattened rhythm	Reduced survival	Stress vulnerability
Corticosteroids	Exogenous glucocorticoids	Mania induction	Supportive cancer care	High psychiatric risk
Genetics	Shared single nucleotide polymorphisms	Immune-related genes	Cancer susceptibility	Biological vulnerability
Lithium	Glycogen-synthase-kinase 3β inhibition	Mood stabilization	Anti-proliferative effects (preclinical)	Requires strict monitoring
Drug interactions	Cytochrome P450 modulation	Pharmacokinetic/pharmacodynamic alterations	Chemotherapy toxicity	Need interdisciplinary care

It summarizes the main biological and treatment-related domains that converge in bipolar disorder and cancer. For each domain, the underlying mechanism, evidence in bipolar disorder, evidence in cancer, and key clinical implications are reported. It highlights how chronic inflammation, hypothalamic-pituitary-adrenal axis dysregulation, corticosteroid exposure, shared genetic susceptibility, lithium-related molecular pathways, and pharmacokinetic and pharmacodynamic drug-drug interactions may jointly contribute to mood destabilization and adverse oncological outcomes, underscoring the need for interdisciplinary clinical management. BD: Bipolar disorder.