PubMed · 9365485
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M Griffiths. 1997-11-08. "Underpowered" trials.. https://doi.org/10.1016/s0140-6736(05)65189-6
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BACKGROUND: Prostate cancer has displayed an increase in incidence unparalleled by any other tumor in the last two decades, with a steady, more gradual increase in mortality rate. Current curative strategies are focused on the detection and treatment of early-stage (T1-2 N0 M0), clinically significant tumors. METHODS: To this aim, refinement of surgical approaches, with appropriate adjuvant therapies, will ensure more complete cancer control, while minimizing associated morbidity. New delivery systems for radiotherapy, as well as other energy sources, are evolving, while a number of promising pharmacological agents, including angiogenesis inhibitors and drugs which alter signal transduction pathways, are currently under investigation. Early detection is also being facilitated by a more widespread implementation of screening programs. Advances in tumor markers, and imaging and biopsy techniques, will allow more accurate preoperative staging. These, coupled with improvements in prognostic markers, aid the physician and patient alike in deciding on the suitability of treatment options with better estimation of outcome. Perhaps the most exciting developments in prostate cancer will come from knowledge of the molecular mechanisms underlying carcinogenesis. The potential for the development of diagnostic and therapeutic tools is immense. The efficacy of treatment can be studied at a molecular level, and strategies for preventing or slowing the development of malignancy can be formulated. RESULTS AND CONCLUSIONS Application of this knowledge in the form of gene and cellular therapy and in the development of novel systemic agents is beginning to enter the realm of clinical practice, and it may be in this field that means for cure and prevention of prostate cancer will eventually be found.
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In the development of medical treatments, identification of promising therapies and inference on selected treatments are usually performed in subsequent separate trials. An adaptive two-stage design is proposed for the situation of multiple treatments to be compared with a control, allowing integration of both steps within a single confirmatory trial controlling the multiple level alpha. After the interim analysis, the trial may be terminated early or is continued with a second stage, where the set of treatments may be reduced due to lack of efficacy or to safety problems. The procedure is highly flexible with respect to the distributional assumptions, stopping rules and selection criteria and allows a completely free recalculation of the sample size for the second stage. Simulations show that the method may be substantially more powerful than classical one-stage multiple treatment designs with the same total sample size. As in conventional strategies with a series of separate experiments, a reasonable selection strategy has to be applied in order to prevent proceeding with non-optimal treatments.