Abstract
Outcome research is a new interesting field in medical research. Some years ago, a document of the American Society of Clinical Oncology distinguished the outcomes of a treatment into patient-outcomes (overall survival and quality of life) and cancer-outcomes (response rate), giving higher priority to patient outcomes. This document is one of the best structured instruments to evaluate and classify the outcomes in clinical oncology. Nevertheless, although overall survival and quality of life represent the main patient outcomes in clinical oncology, in the last years many researchers tried to overcome these recommendations, creating new surrogate end points to assess overall survival and quality of life. Surrogate end points can be useful tools when they are used to achieve preliminary data that anticipate the evaluation of the final outcome, but the use of surrogate end points instead of the main outcomes is quite dangerous, as it can provide wrong answers to clinical questions. The use (or abuse) of surrogate end points of quality of life has recently favoured some questionable decisions of the main regulator organs, such as the approval by the Food and Drugs Administration of the use of gemcitabine in advanced chemotherapy-naive pancreatic cancer, or mitoxantrone in the palliative treatment of hormone-resistant pancreatic cancer, based on the improvement in clinical benefit (a non-validated instrument to evaluate the outcome of palliative chemotherapy) besides a minimal and questionable overall survival, or pain control (evaluated with a non-validated instrument). A correct use of surrogate end points of quality of life within and not instead of quality of life assessment should be the engagement of our further efforts in quality of life research.
Highlights
Many authors highlighted the importance of outcome research in oncology, either in clinical research or in daily clinical practice [1,2]
Surrogate end points are largely used in clinical research, and their use can not be considered wrong by a conceptual point of view
The use of a surrogate end point instead of a final outcome is wrong by a methodological point of view and can lead to draw misleading conclusions
Summary
Many authors highlighted the importance of outcome research in oncology, either in clinical research or in daily clinical practice [1,2]. On the basis of the improvement in overall survival and clinical benefit [19], in 1997 the FDA registered gemcitabine as the treatment of choice in advanced pancreatic cancer, assuming clinical benefit as a surrogate end point of quality of life, and paving the way for a new dangerous era in quality of life assessment. In 1996 Tannock et al published the results of a trial investigating the use of mitoxantrone in advanced hormone-resistant prostate cancer [27] This trial had some limits, that were similar to those weakening the trials focused on clinical benefit in advanced pancreatic cancer: primary end point was pain control; pain was assessed using non-validated instruments; the reduction in opiate consumption was a secondary end point; the control arm received corticosteroids, that is a questionable treatment if pain control is the primary end point. A further dimension in which the use of surrogate end points of quality of life
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