Association of serum IL-6 levels with comprehensive geriatric assessment variables in a population of elderly cancer patients

The primary aim of this study was to find whether any association exists between serum levels of proinflammatory cytokines, mainly IL-6, and the most important comprehensive geriatric assessment (CGA) variables such as functional status, cognitive functions and nutrition in a population of elderly cancer patients. The secondary aims were to find whether any difference existed between: i) age groups, ii) performance status scores, iii) patients who had lost weight versus those who had not. Eighty-four elderly patients with advanced cancer were included in the study (stage III 15.4%, and stage IV 72.6%). Serum levels of IL-6 and CRP were significantly higher in elderly than in the other adult cancer patients. Among the CGA variables investigated, the most affected were functional status assessed by IADL, cognitive functions by MMSE and nutrition. The ECOG PS was shown to be significantly associated with all the dimensions of CGA investigated: poor PS (>/=2) corresponded to severe disabilities. As for the relationship of serum IL-6 with CGA variables, the strongest correlations were between IL-6 and functional status assessed by both Katz ADL (p=0.0003), IADL (p=0.0070) and nutrition (p=0.0013). Moreover, we observed an association, although not statistically significant, between functional disability (ADL and IADL) and high IL-6 levels in individuals with weight loss. IL-6 levels seem to be independently associated with all CGA variables investigated in the present study in a population of elderly cancer patients. Because the most important CGA variables, in particular functional status, have been observed to be strongly associated with survival, the present study, confirming our previously reported ones, suggests that IL-6 may be a reliable marker of disease outcome and supports the feasibility of using IL-6 as a sensitive outcome marker in studies based on novel approaches aiming at modifying age- and cancer-related biologic mechanisms.