Patterns of staging, treatment, and mortality in gastric, colorectal, and lung cancer among older adults with and without preexisting dementia: a Japanese multicentre cohort study.

Older cancer patients with preexisting dementia are less likely to receive standard cancer treatment and more likely to experience poorer outcomes. Clinicians should be aware of these risks, and would benefit from standardised guidelines to aid their decision-making in diagnosing and treating these patients.