Oncogeriatrics (part 5.) The role of comorbidities in older patients with cancer

Comorbidity is defined as the presence of one or more additional conditions co-occurring with primary indices. Comor­bidity is common in older cancer patients. Its prevalence, however, is difficult to determine and varies by cancer site. There is no single reason for which comorbidity and cancer coexist, but chronic diseases and cancer are both common in older age and share many risk factors. There is no consensus on how should comorbidity be measured. Even though many comorbidity indices have been developed so far, no unified, widely used instrument exists. Patients with comorbidities have worse outcomes compared to those with no such conditions. They may experience diagnostic and therapeutic delay and be disqualified from radical treatment more often. Moreover, they are more likely to suffer from treatment-related complications and have worse overall survival. It seems important to assess the comorbidity status as a part of individualised oncologic treatment planning. However, as data regarding its significance are insufficient and in many cases conflicting, patients with comorbidity should not be routinely considered as not fit enough for a radical treatment. Therefore, to adequately address all of the concerns that have been raised, a broader participation of older, comorbid patients in clinical trials is needed.