A meta-analysis of 105 samples from 76 prospective studies found that depression is associated with increased cancer mortality. Depression diagnosis and higher levels of depressive symptoms predicted elevated mortality in both studies assessing depression before and after cancer diagnosis. The association remained significant even after controlling for medical confounders. However, the association was weaker in studies with longer intervals between depression and mortality assessments, in younger samples, and when using the Beck Depression Inventory compared to other scales. Depression was more strongly associated with mortality in community-based studies than in clinical samples. The effect of depression on mortality was strongest in studies with shorter intervals between depression assessment and mortality. Depression diagnosis showed slightly larger associations with mortality than depressive symptoms, though the difference was not statistically significant. The association between depression and mortality was similar across cancer sites, stages, and gender. The study concluded that depression screening should be routine in cancer treatment settings, and referrals to mental health specialists should be considered. Further research is needed to determine if treating depression could improve survival in cancer patients.A meta-analysis of 105 samples from 76 prospective studies found that depression is associated with increased cancer mortality. Depression diagnosis and higher levels of depressive symptoms predicted elevated mortality in both studies assessing depression before and after cancer diagnosis. The association remained significant even after controlling for medical confounders. However, the association was weaker in studies with longer intervals between depression and mortality assessments, in younger samples, and when using the Beck Depression Inventory compared to other scales. Depression was more strongly associated with mortality in community-based studies than in clinical samples. The effect of depression on mortality was strongest in studies with shorter intervals between depression assessment and mortality. Depression diagnosis showed slightly larger associations with mortality than depressive symptoms, though the difference was not statistically significant. The association between depression and mortality was similar across cancer sites, stages, and gender. The study concluded that depression screening should be routine in cancer treatment settings, and referrals to mental health specialists should be considered. Further research is needed to determine if treating depression could improve survival in cancer patients.