Postprostatectomy adjuvant versus salvage radiotherapy: a complication-adjusted number-needed-to-treat analysis

Radiotherapy (RT) has been used with success after radical retropubic prostatectomy (RRP), both in the adjuvant and salvage settings. The purpose of the current investigation was to systematically compare adjuvant versus salvage RT in a manner that incorporates both treatment efficacy and complications.

A literature review was performed of reports of post-RRP salvage and adjuvant RT, and 12 trials comprising 1060 patients met the appropriate inclusion criteria. The biochemical failure-free survival in each study/arm was tabulated, and these values were entered into a model to compute an unadjusted number-needed-to treat (NNT). RT complications were then considered, accounting for differences in toxicity incidences in the salvage versus adjuvant setting, to compute complication-adjusted NNTs. In all the trials, the signs and magnitudes of the NNTs obtained were used to compare adjuvant with salvage RT.

The absolute NNT analysis showed an advantage of adjuvant compared with salvage RT. After adjustment for RT complications, however, the advantage shifted to salvage RT. This transition point from superiority of adjuvant RT to superiority of salvage RT was sensitive to the estimated incidence and severity of RT side effects.

Adjuvant post-RRP RT was advantageous in comparison to salvage RT if the side effects of RT were estimated to be negligible. However, with moderate incidence/severity of RT side effects, salvage RT was advantageous. The findings herein must be tested in a prospective study in which both health-related quality of life and cancer control are documented in patients receiving adjuvant versus salvage post-RRP RT. Further work is needed to better estimate parameters entered into the model to determine the precise transition point between adjuvant and salvage RT with modern RT techniques.