Barriers to taking part in trials

Although many patients are eligible to enter trials of cancer therapy, accrual rates are low and it is estimated that on average around 5 per cent of UK patients [1] and 3 per cent of US patients [2] take part. Trials generally rely on a minority of clinicians who have a particular interest in research and who recruit the majority of patients. However, even among highly committed doctors, accrual rates can be low. For example, a survey of members of the research-oriented US Eastern Cooperative Oncology Group (ECOG) found that doctors overestimated the number of patients they intended to enter in trials by a factor of six. Members entered less than 10 per cent of eligible patients to ECOG trials and 62 per cent did not enter a single patient during the 12-month period of the survey [3]. Although a survey of British oncologists [4] found that almost all of the 65 per cent who responded stated that they were participating in clinical trials, three-quarters of respondents acknowledged that they were entering less than half of all eligible patients. A study of enrolment to trials at a US Cancer Centre, conducted over three separate six-month periods, found that even with a certain level of promotion during which clinicians were reminded of the availability of trial protocols, a relatively low proportion of patients entered trials [2]. Of 276 eligible patients, only 171 were considered for trial entry by the clinician and a suitable protocol was available for ninety-one of them. Out of these, seventy-six met the eligibility criteria of the particular trial for which they were considered, thirty-nine agreed to participate and thirty-six did not. It is worth noting that the greatest numbers were lost at the earliest stage before the clinician had reviewed protocol availability and eligibility criteria.

Similarly, in the ECOG survey [3], doctors appeared to select patients with whom to discuss possible participation in trials according to their own additional eligibility criteria. Those with poor disease status or those thought to have a lack of trust in medicine were not considered for trials, even though the clinicians involved believed that trial patients were given a higher quality of care. Most felt that randomization was a very difficult concept to explain and therefore a powerful obstacle, which limited their own ability to participate in clinical trials. In the UK survey [4] many commented that lack of time or resources were barriers to trial recruitment and others cited difficulties in obtaining informed consent as being a particular problem. Perceived intelligence was cited as the most important factor influencing the ease of communicating about trials with patients. Most doctors indicated that it was easier to approach more intelligent patients, although a minority found that patients with poorer understanding were easier [3]. Likewise, senior oncologists attending communication skills courses have indicated that providing complex information about trials and obtaining informed consent are the most difficult aspects of communicating with patients [5].

Overall, it seems that doctors are relatively pessimistic about the likely reactions of at least a proportion of their patients to invitations to take part in trials. However, studies of public opinion have indicated that the general public is supportive of clinical research. Far larger proportions of people say that, in theory, they would be willing to take part in trials than is suggested by current accrual rates. For example, in a professional survey of over a thousand adults carried out in the UK during the 1980s, two thirds of those interviewed said they would be prepared to participate in clinical trials. This was even in the most demanding of circumstances, trials of lumpectomy versus mastectomy for women and amputation versus bone grafting for men [6]. There was however a strong tendency for younger and more highly educated people to want to have a say in choosing their own treatment, which might preclude them from trials. A criticism of this type of opinion seeking is that people may react differently to hypothetical and actual situations. Faced with a theoretical scenario, many may feel that they would wish to take part in a trial whereas they may well act differently in reality. However, it seems that the views of those who are ill are in broad agreement with the healthy, and are generally supportive of clinical research. For example, in a survey of seventy-five cancer patients carried out in seven oncology centres in the UK, 42 per cent said they would agree to take part in research trials, 10 per cent that they would not, and 48 per cent were uncertain [7]. Those who indicated that they did not want to take part, or were uncertain, said that this was mostly because they would prefer the doctor to make the decision, or that they would worry about receiving a new treatment. The particular aspects of trials that were cited as particularly appealing or unappealing are summarised in Table 2.1. Another study of 325 patients attending two major cancer centres in the UK found that more than 90 per cent of those interviewed believed that patients should be asked to take part in medical

Table 2.1 Characteristics of trials cited as particularly appealing or unappealing by cancer patients (Kemp etal. 1984)

Characteristics Scored greatly

(un)appealing %


Greater chance of treatment by doctor with special interest in particular cancer 83

Progress monitored closely 80 Taking part contributes to research knowledge and benefits humanity 75

Likely to obtain more information about condition 75

Greater chance of obtaining new treatments 72

Not appealing

Don't choose treatment oneself 25

Treatment decided by trial not doctor 24

Greater chance of obtaining experimental treatments 1 5

research. However, only three-quarters said that they would be prepared to take part themselves, and less than half if the trial was randomized. Encouragingly, when given more details and further explanation of randomization more than half of those who had initially refused, or were unsure about randomization, changed their mind [8].

It seems that a limiting factor to including a greater proportion of eligible patients in trials maybe in motivating more doctors to take part in research and to discuss possible participation in trials with more of their patients. Undoubtedly, time and resource issues are involved in clinicians' reluctance, but it also seems that many are uncomfortable about discussing trials and in particular, randomization with their patients. Better training in communication, both generally and specifically relating to trials and randomization, could be a way of tackling this difficulty. The clinical trials community should be ready to initiate and become involved in such educational activities. Ensuring that good written explanations along with other material, such as explanatory videos, are available for all trials may also provide useful support for those at the front-line of discussing trials with potential participants.

The issue of patients' willingness to participate in trials is a key determinant of success. Little is known about what precisely motivates individuals to take part in trials although most studies have indicated that participation is driven more by self-interest than altruism [9]. It is often thought that individuals take part in trials for the public good and improvement of treatment for future patients. Whilst this may be entirely true for some and in part for many, studies of patients' attitudes have revealed that the main motivation is the hope or expectation of gaining a benefit from the new treatment. Published research seems to show that the majority of those who take part in trials are generally satisfied with the experience [10,11]. Furthermore, systematic reviews of research studies, that have compared patients enrolled in clinical trials with those treated outside of trials, have concluded that overall there is evidence (albeit weak and in need of further study) that trial participants have received better care and have had better outcomes [12,13].

Encouragingly, when given appropriate explanation, the majority of the public appear enthusiastic or uncertain about entering trials. Only a small minority are unwilling to participate and we maybe relatively optimistic that given the appropriate information, and support, the public will remain strong supporters of clinical research. Ultimately this may have the effect of encouraging consumer pressure on doctors to be more active in clinical trials.

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