In recent years, progress in extending survival in most common cancers has mainly been achieved in small incremental steps. In this situation, other outcomes such as progression-free survival, response rates, toxicity, treatment-related deaths, cost, and particularly quality of life (QL), can help determine whether new treatments should, or should not, be pursued. There is therefore an increasing demand that cancer treatments be assessed in the wider framework of the balance between all the benefits and risks so that patients and their clinicians can make individual informed decisions.
As a consequence, from being a somewhat neglected area, QL has become a widely researched area and it could be argued that, at least in the context of clinical trials, it has become somewhat overused. The increase in interest can be gauged from the fact that the average number of papers per year with 'Quality of Life' in their title in the 1970s was sixteen, in the 1980s it rose to eighty-five, and in the 1990s there were over 400. It seems that it is now almost obligatory to include an assessment of QL into every new clinical trial. Indeed the pressure is so strong from all parties, including patients, ethics committees, sponsors, and journal editors, that it may sometimes appear difficult and potentially risky to leave it out, even though the trial may not demand it. A decision not to include QL in a trial can all too easily be interpreted as 'we don't care about patients' QL.' However, the result appears to be that many trials simply bolt on an assessment of QL, without considering whether it has the potential to influence decisions. This results in the collection of huge quantities of largely irrelevant data, the use of considerable resource, overburdening of patients, and a trawl through the data for data-dependent results. Consequently, although QL has often been used as supporting evidence for or against a regimen, in only a small proportion of the trials in which QL has been collected has it played the major role in interpreting the results of a trial.
Investigators therefore need to consider carefully the basis for including QL in their trial, and specifically whether including QL is important for the outcome of the trial. In this chapter we place a lot of emphasis on the importance of defining a QL hypothesis. Such a hypothesis can be generated by clinicians, nurses, patients, or combinations of these groups. A pre-specified hypothesis provides a focus for what aspects of QL, if any, should be measured in a trial.
It could be argued that QL is not particularly relevant in many cancer trials, given the evidence that most patients will accept any reasonable toxicity and a consequent reduction in their quality of life for an increased chance of cure. Indeed Slevin etal.  showed that patients would accept an intensive treatment (with a considerable number of side-effects and drawbacks such as nausea, vomiting, hair loss, frequent use of needles and drips, 3-4 days per month in hospital, decreased sexual interest and possible infertility) if there was even a 1 per cent chance of cure. However, when cure is not possible, a decision often needs to be made about giving treatment which may result in a longer survival but poorer QL, or reducing or stopping treatment which may result in a shorter survival but better QL. In reality things are seldom so clear cut, but the American Society of Clinical Oncology (ASCO) guidelines adopted in 1995 stated that 'treatment can be recommended in metastatic cancer even without an improvement in survival, if it improves quality of life' .
We propose that, in order for QL to truly take its place as an important outcome, trial designers need to focus on the key questions, collect good data, and agree on standard methods of analysing and presenting the data. The recent upsurge of interest in QL does not necessarily mean that rigorous methods for design and analysis are widely available or applied. For instance, Schumacher et al.  reviewed reports of clinical trials that had 'Quality of Life' in the title, keyword or abstract. They found that only about a third included a detailed QL evaluation with a validated instrument, and that over 40 per cent appeared to use the term QL merely as a 'catch-phrase.'
Nevertheless, several general and cancer-specific questionnaires have now been painstakingly developed and validated and can be considered as 'standard.' However, for many of the issues associated with fully integrating QL into randomized clinical trials, such as improving compliance, standardizing analyses, and interpreting the QL scores obtained, many questions remain.
The aim of this chapter is to give some guidance as to the appropriate use of QL in cancer clinical trials with particular emphasis on practical issues.
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