Comorbid chronic diseases and cancer diagnosis: disease-specific effects and underlying mechanisms

Early diagnosis of cancer is a key strategy to improve patient outcomes. However, many people with possible symptoms of cancer also have pre-existing chronic diseases (i.e. comorbidities/multimorbidities), which can complicate the diagnostic process and potentially affect the timeliness of diagnosis. Evidence suggests that pulmonary, cardiovascular, neurological and psychiatric disorders are associated with longer intervals before cancer diagnosis and more advanced-stage disease at diagnosis. Other chronic conditions such as hypertension and certain gastrointestinal and musculoskeletal conditions can be associated with a more timely diagnosis. The effect of pre-existing chronic conditions on cancer diagnosis appears to vary depending on the disease type and nature of the presenting symptoms. This review proposes a comprehensive framework that encompasses the effects of disease-specific, patient-related and health-care-related factors on the diagnosis of cancer in individuals with pre-existing chronic illnesses. By considering the specific effects of chronic diseases on diagnostic processes, tailored early diagnosis initiatives can be developed to help improve the outcomes of the large proportion of patients with cancer who have comorbid chronic conditions.

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