Quality of life research: adding an important dimension to the evaluation of therapeutic outcomes

Patients facing a cancer diagnosis and difficult treatment regimen are forced to deal with concerns about their own mortality and the effect on loved ones, job, and financial issues, as well as possible depression and concern about dealing with the physical effects of therapy on their health [1]. Fortunately, survival for patients with diffuse large B-cell lymphoma (DLBCL) has improved as a result of CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) therapy, originally administered with a cycle duration of 21 days, and further enhanced by a reduction of cycle length to 14 days (dose-dense therapy) and by the addition of the monoclonal anti-CD20 antibody rituximab [2,3]. However, concern has been raised about additional toxicities with this regimen [4,5]. The study reported in this issue of Leukemia & Lymphoma by Tholstrup et al. on ‘Quality of life in patients with diffuse large B-cell lymphoma treated with dosedense chemotherapy is only affected temporarily’ [6] provides another dimension in evaluation of this therapy, finding that it has only short-term effects on quality of life, thus giving newly diagnosed patients a measure of hope and additional incentive to complete this regimen because it shows that their global health status, physical, and role functions will return to baseline levels within 3 months after completion of therapy. R-CHOP (CHOP with rituximab) therapy has been quantitatively evaluated from a number of perspectives. Randomized clinical trials beginning in 2002 consistently demonstrated a survival advantage, leading to evidence-based recommendations that previously untreated patients with DLBCL who are candidates for curative intent with combination therapy should receive rituximab [7]. Economic analyses have demonstrated that the addition of rituximab is cost-effective [8]. However, the measurement of quality of life outcomes is more varied and subjective. Quality of life, or more specifically health related quality of life (HRQoL), has been studied from multiple perspectives. It is important that the questions selected to assess it have been validated to reflect a specific conceptual model [9]. In general, however, it is agreed that these questionnaires should cover physical, social, and psychological/emotional functioning and well-being, as well as some symptoms [10]. Other characteristics of a good measure are its reliablility (i.e. repeated uses under similar circumstances will provide similar results), sensitivity (i.e. able to discriminate between patients with different treatments or in different groups), and responsiveness (i.e. able to demonstrate changes over time) [10]. Finally, the measure should be clinically meaningful such that differences between groups or over time can be interpreted as being clinically significant. Tholstrup et al. [6] selected the European Organization for the Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ) including 30 questions, version 3 [11], abbreviated as the EORTCQLQ30, which is one of the most widely used measures of overall quality of life in studies of patients with cancer on clinical trials. However, while other valid instruments exist, they may not be comparable, and thus it is necessary to compare studies using the same instrument [12].