Functional Assessment and the Cancer Survivor: Something Old, Something New
Authors: H. J. Cohen
Journal: JNCI Journal of the National Cancer Institute (2010)

The increasing number of cancer survivors in this country can be attributed in part to improvements in cancer treatment as well as to the increasing age of the population and thus higher prevalence of cancer. The recent attention directed toward this phenomenon (1) has largely centered on appropriateness of care for the cancer survivor, who has too often become lost in the system and fallen into the cracks between care providers. Thus, it is critical that cancer survivors be evaluated for clues to the prediction of potential outcomes and, of perhaps greater importance, for clues to management opportunities that might improve these outcomes. The Institute of Medicine and others have called for cancer survivorship plans (1,2). However such plans need to be guided by evidence. The report by Braithwaite et al. (3) in this issue of the Journal provides important information to inform survivorship plans from both perspectives—prognostication and management. The authors assessed physical functioning using a battery of well-accepted tools in a large cohort of women (for an average of 21 months after diagnosis) who had completed treatment for breast cancer and followed them for survival and the occurrence of new events for an average of 9 years (95% followed for >6 years). Unfortunately, this assessment was not done before initiation of therapy, which would have provided a level of potentially useful additional information. Nevertheless, follow-up was excellent, and very important information has emerged. First, the authors have documented that functional limitations are common in such subjects, with 39% exhibiting at least one limitation. Moreover, the prevalence of functional limitations increased with age so that approximately 50% of those older than 65 had at least one such limitation. Second, the presence of functional limitations was strongly predictive of all-cause mortality. The driver of this outcome was the impact on competing cause (ie, non-breast cancer mortality) and not breast cancer mortality. This impact was seen across all age and body mass index groups, although the hazard ratios were somewhat higher in the older age groups. It is relevant that this was a relatively young cohort of breast cancer patients (median age 57), and one suspects that the relationships between age and functional limitations might have been more striking had there been a more proportionate representation of older subjects. Moreover, although body mass index did not appear to have a differential effect on the impact of functional limitations, almost two-thirds of these subjects were overweight or obese, and three-quarters had at least one comorbidity (greater in those with limitations), suggesting both groups as potential targets for intervention. There is substantial evidence to suggest that increased body mass index, comorbidities, and functional limitations generally predict subsequent functional status decline (4). This study was only able to assess mortality outcomes, but it is likely that a major additional burden of functional limitations will be seen in such patients as they age (5). Another important contribution is the observation that the impact of functional limitations was seen largely in patients with early-stage disease, not in those with advanced stage, where the effect of the cancer per se appears to override the impact of functional limitations on survival. This new information fits well into and enhances our broader understanding of the issues surrounding functional status assessment and cancer outcomes. Oncologists have long recognized the importance of functional status, harkening back to the widespread use of first, Karnofsky Performance Status (KPS), and then Eastern Cooperative Oncology Group (ECOG) performance status (6). These have largely been used and have been shown to be important predictors of outcome in the initial treatment of the cancer patient. With the growth of the discipline of geriatrics and more recently of geriatric oncology, a broader assessment of functional status using tools such as those used by Braithwaite et al. (3), has been shown to predict outcomes better than KPS or ECOG alone (6,7). In fact, the assessment of functional status and