Tumor control probability for permanent implants in prostate

The tumor control probabilities (TCPs) for 11 transperineal permanent implants of the prostate with 125I seeds have been computed, based on target-specific volume-dose histogram data. Prostate dose-response of this modality is converted from that of external beam therapy based on biologically effective dose derived from the alpha beta model. The calculated TCPs for these transperineal prostate cases are compared with the results of 679 previous retropubic implants, providing interesting insight about these two techniques. Further refinement and validation of this model await long-term followup results of sufficient number of patients.