Fatigue in renal cell carcinoma: the hidden burden of current targeted therapies.

Fatigue is one of the most common symptoms associated with cancer. Persistent fatigue can impair multiple aspects of daily functioning and quality of life, and patients report that treatment-related fatigue has a greater impact than other symptoms, including pain, nausea, and depression. Thus, management of fatigue is recognized as an important component of care for patients with cancer. Treatment of advanced and metastatic renal cell carcinoma (RCC) was, until recently, limited to cytokine-based therapies, which are associated with modest response rates and significant toxicity, including high rates of treatment-related fatigue. The paradigm for RCC treatment has shifted dramatically in the last 5 years with the advent of efficacious targeted therapies. These agents provide the promise of better tolerability because of their more selective mechanisms of action. However, there is considerable variation in the selectivity of targeted agents for RCC, and a review of randomized clinical trials in patients with advanced and/or metastatic disease reveals that there is considerable variation in the tolerability of these agents. Fatigue remains a prominent toxicity with current targeted therapies. Future agents that show better selectivity and potency than current targeted therapies should help to provide better efficacy and tolerability.