Randomized controlled trials are often described as the gold standard by which reliable medical knowledge is validated. They constitute the most persuasive way to test the validity of hypotheses that emerge from phase 2 studies. Randomization is central to ruling out the confounding factors, especially patient selection biases that confound comparisons of an investigational therapy with historical controls, and treatment biases that may reflect practice at a single institution.
Oncology is noteworthy in its commitment to clinical trials, including phase 3 randomized trials. The NCI has the most developed system of clinical trial support of any of the institutes of the NIH. The NCI cancer cooperative groups have existed for 50 years. The NCI also supports clinical trials through its comprehensive cancer centers and through community cancer centers. ASCO has exercised leadership in the promotion of cancer clinical trials. Its annual meetings present the results of many clinical trials and include sessions on the organization and conduct of such trials.
It is essential, nevertheless, to recognize that deep ambivalence exists within medicine, including oncology, toward randomized clinical trials. Harry Marks (1997) provided a historical account of the struggle to establish the importance of randomized clinical trials in medicine after World War II. Barron Lerner (2001)
documented the complex process by which randomized trials came to be adopted as a guide to clinical practice in oncology, especially in the challenge by Bernard Fisher to the Halstead radical mastectomy in breast cancer.
Phase 3 randomized trials are clearly difficult to mount (as we discuss in chapter 8). An oft-cited figure is that only 3%-5% of adult cancer patients are entered into randomized clinical trials. This is due to many factors, prominent among them patient resistance to randomization. On the one hand, ineffective standard therapy may encourage patients to seek experimental treatment outside of trials. Patients with a terminal illness, such as stage IV breast cancer, may say that they have nothing to lose from seeking access to new treatments, further complicating efforts to conduct randomized trials. On the other hand, some patients may be unwilling to risk exposure to the experimental procedure within a trial, viewing the untested negatively. Physician incentives to encourage patient participation in randomized trials are often weak or negative. Although some compensation for research is generally provided, the time required to persuade a patient to enter a trial is often substantial and seldom compensated. The costs of care for a patient who is randomized to the experimental treatment are often not compensated, further costing physicians money.
Ambivalence among many oncologists must be counted among the difficulties of organizing randomized trials. Belief in the value of trials may conflict with belief in the value of a treatment outside a trial. In 1991, Belanger et al. reported on a survey of 230 oncologists about "the impact of clinical trials" on their preferred methods of treating breast cancer. They found that preferred treatments for primary breast cancer and inflammatory breast cancer were supported by clinical trials; that adjuvant chemotherapy for node-negative breast cancer was not based on consistent improvement in survival; and that adjuvant chemotherapy for postmenopausal women with node-positive breast cancer was contrary to results from large randomized clinical trials. They suggested "that even large randomized clinical trials may have a minimal impact on practice if their results run counter to belief in the value of the treatment" (p. 7).
Oncology was divided about the need for phase 3 randomized clinical trials of HDC/ABMT. Skeptics believed such trials were essential to determine whether the procedure was superior to standard therapy. Believers, with varying degrees of enthusiasm, believed that the results of phase 2 studies justified wider clinical use of the procedure without trials. Some regarded phase 2 results as so persuasive that randomization was unethical. Others straddled both camps. Peters both acknowledged the importance of clinical trials and played a major role in organizing them but firmly believed that trials would confirm the superiority of HDC/ABMT. Simultaneously, he advocated that insurance companies should cover the procedure as effective treatment. Still others thought that the responsiveness of metastatic breast cancer to HDC/ABMT could be extrapolated to stage II high-risk breast cancer, even though the biology was different. These divisions within oncology were masked to patients and the general public. Many enthusiasts, in Henderson's view (2002), found themselves torn between their own uncertainty about the procedure and the need to defend it so claims to insurers would not be denied and so the medical profession, not health insurers, would decide its value.
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