A systematic review of the prevalence of comorbid cancer and dementia and its implications for cancer-related care

Objectives: A comorbid diagnosis of cancer and dementia (cancer-dementia) may have uniqueimplications for patient cancer-related experience. The objectives were to estimate prevalence ofcancer-dementia and related experiences of people with dementia, their carers and cancer cliniciansincluding cancer screening, diagnosis, treatment and palliative care. Method: Databases weresearched (CINAHL, Psychinfo, Medline, Embase, BNI) using key terms such as dementia, cancer andexperience. Inclusion criteria were: a) English language, b) published any time until early 2016, c)diagnosis of cancer-dementia and d) original articles that assessed prevalence and/or cancer-relatedexperiences including screening, cancer treatment and survival. Due to variations in study design andoutcomes, study data were synthesized narratively. Results: Forty-seven studies were included in thereview with a mix of quantitative (n = 44) and qualitative (n = 3) methodologies. Thirty-four studiesreported varied cancer-dementia prevalence rates (range 0.2-45.6%); the others reported reducedlikelihood of receiving: cancer screening, cancer staging information, cancer treatment with curativeintent and pain management, compared to those with cancer only. The findings indicate poorercancer-related clinical outcomes including late diagnosis and higher mortality rates in those withcancer-dementia despite greater health service use. Conclusions: There is a dearth of good qualityevidence investigating the cancer-dementia prevalence and its implications for successful cancertreatment. Findings suggest that dementia is associated with poorer cancer outcomes although thereasons for this are not yet clear. Further research is needed to better understand the impact of cancerdementiaand enable patients, carers and clinicians to make informed cancer-related decisions