Approaching clinical problems in prostate cancer radiotherapy using the number needed to treat (NNT) technique.

The goals of this article are to review the application of the number needed to treat (NNT) concept to selected clinical problems in prostate cancer radiotherapy. Particular emphasis will be placed on (1) comparison of radiotherapy with other treatment options for early-stage disease, (2) the role of hormone therapy in addition to radiotherapy over a spectrum of disease presentation, and (3) systematic comparison of adjuvant versus salvage radiotherapy in the post-prostatectomy setting. Limitations of NNT calculations based on non-randomized comparisons also are discussed.