[Studies on localized low-risk prostate cancer : Do we know enough?]

BACKGROUND: Treatment of localized low-risk prostate cancer (PCa) is undergoing a paradigm shift: Invasive treatments such as surgery and radiation therapy are being replaced by defensive strategies such as active surveillance (AS) and watchful waiting (WW).

OBJECTIVE: The aim of this work is to evaluate the significance of current studies regarding defensive strategies (AS and WW).

METHODS: The best-known AS studies are critically evaluated for their significance in terms of input criteria, follow-up criteria, and statistical significance.

RESULTS: The difficulties faced by randomized studies in answering the question of the best treatment for low-risk cancer in two or even more study groups with known low tumor-specific mortality are clearly shown. Some studies fail because of the objective, others-like PIVOT-are underpowered. ProtecT, a renowned randomized, controlled trial (RCT), lists systematic and statistical shortcomings in detail.

CONCLUSION: The time and effort required for RCTs to answer the question of which therapy is best for locally limited low-risk cancer is very large because the low specific mortality rate requires a large number of participants and a long study duration. In any case, RCTs create hand-picked cohorts for statistical evaluation that have little to do with care in daily clinical practice. The necessary randomization is also offset by the decision-making of the informed patient. If further studies of low-risk PCa are needed, they will need real-world conditions that an RCT can not provide. To obtain clinically relevant results, we need to rethink things: When planning the study, biometricians and clinicians must understand that the statistical methods used in RCTs are of limited use and they must select a method (e.g. propensity scores) appropriate for health care research.