['The role of neoadjuvant androgen withdrawal before radical prostatectomy continues to be defined and remains investigational. It is unknown whether decreases in positive margin rates will translate into lower biochemical and local recurrence rates until long-term followup is available. We determined whether local recurrence rates after tumor excision were less with neoadjuvant compared to adjuvant androgen ablation in the Shionogi tumor model. Androgen withdrawal in this model triggers apoptosis and complete tumor regression but rapidly growing androgen independent tumors inevitably recur after 1 month. Conceptually, the ideal time for excision is after maximal castration induced tumor involution but before outgrowth of androgen resistant clones.', 'Shionogi tumors were allowed to grow to 1 to 2 gm. before mice were randomly assigned to group 1-tumor excision with wide margins and castration at tumor recurrence and group 2-neoadjuvant castration for 10 days followed by wide excision of the regressed tumor.', 'Tumors recurred locally in 87% of group 1 mice after a median of 17 days (range 6 to 24) and all regressed completely with adjuvant castration. However, androgen independent tumors recurred in 92% of mice after a median of 36 days. In group 2 androgen independent disease recurred in 44% of mice after a median of 40 days. Tumor-free survival was significantly greater in group 2 than in group 1 (56 versus 20%, respectively, p <0.05). Inked surgical resection margins were positive in two-thirds of group 1 and one-third of group 2 mice.'] Does neoadjuvant androgen withdrawal therapy decrease local recurrence rates following tumor excision in the Shionogi tumor model?