Impact of comorbidity on treatment decision making and outcomes

Abstract

Cancer, like many chronic conditions, is a disease of aging, and more than half of cancer patients in developed countries are 65 years or older. Therefore, many cancer patients have comorbidities, high use of medications, altered body composition, pharmacokinetics, and pharmacodynamics. Therefore, the treatment plans need to be individually tailored to achieve optimal outcomes. This chapter on comorbidity in cancer decision making gives some general principles and then will review some specific comorbidities with their incidence, considerations for decision making and treatment outcome. Scores to assess the risk of toxicity from chemotherapy will also be reviewed. Comorbidity burden is a major influencer of life expectancy and should be integrated in life expectancy estimates. The most assessed comorbidities are renal insufficiency and hepatic diseases. Creatinine clearance should be systematically calculated, and for several types of treatment, the Child-Pugh classification can be used. We also review the treatment of patients with cardiovascular diseases, auto-immune/inflammatory diseases, and diabetes. All risk factors of comorbidity should be comprehensively evaluated before cancer treatment, in order to reduce treatment-related toxicity and improve patient outcomes. Future research should address how to integrate the impact of multiple concomitant comorbidities, and more specifically which subgroups most affect various cancer outcomes.