The indications, rationale, and results of neoadjuvant androgen deprivation in the treatment of prostatic cancer: Memorial Sloan-Kettering Cancer Center results

Neoadjuvant androgen ablation for localized prostatic cancer: pathology methods, surgical end points and meta-analysis of randomized trials

PURPOSE

At least 7 centers or collaborative groups have performed randomized clinical trials of neoadjuvant androgen ablation and radical prostatectomy versus radical prostatectomy alone for localized prostatic cancer. Our objectives were to analyze treatment results in terms of 2 standard outcome measures, to identify patient characteristics and other factors that explain outcome differences between trials, and to use pooled data to test the hypothesis that neoadjuvant treatment alters outcomes.

MATERIALS AND METHODS

Trials were identified by MEDLINE search and review of published bibliographies, and examined for pathological techniques used to assign surgical end points. An attempt was made to contact trial group members for clarification and updated information. The resulting data were transformed as needed into standardized end points of pT stage and negative surgical margin. A series of contingency tables were used to study relationships between treatment outcomes and various risk factors.

RESULTS

In addition to neoadjuvant treatment, numerous risk factors related to treatment regimen and patient characteristics apparently influenced treatment outcome, and should be reanalyzed when future followup trial data become available.

CONCLUSIONS

In radical prostatectomy there is a need for uniform ways to process specimens, assign surgical stage and establish standardized surgical end points. Despite differences in risk factors, the trials were similar in overall design. Within these constraints neoadjuvant androgen ablation was significantly associated with low pT stage and negative surgical margin. Longer followup is needed to validate these measures as good surrogates for tumor specific survival.

Neoadjuvant therapy in localized prostate cancer before surgery and radiotherapy

Neoadjuvant hormonal therapy brings the possibility of improving the results of radical treatment of clinically localized prostate cancer. While the advantages of this therapy combined with radiotherapy and cryosurgery are encouraging, as yet the positive effects of initial hormonal ablation before radical prostatectomy are still not proven.

Androgen ablation in addition to radiation therapy for prostate cancer: is there true benefit?

Prostate cancer patients may now be identified as having a high risk of failing single-modality treatment based on pretreatment prostate specific antigen (PSA), Gleason score, and palpable stage. In particular, a PSA greater than 20 ng/mL portends a biochemical failure rate of 50% to 80% when radiation therapy, surgery, or androgen ablation is administered individually. A number of randomized trials as well as retrospective data show that failure rates are significantly reduced by combining androgen ablation and radiation. The improved results, however, are complicated by the ability to salvage radiation alone-treated patients with androgen ablation and the possibility of less effective salvage (or no effective salvage in the case of permanent androgen ablation) for patients treated with androgen ablation plus radiation. Thus, survival, which is obscured by high rates of intercurrent deaths in this elderly population, is the most important end point in such studies. Two randomized trials, one from the Radiation Therapy Oncology Group (RTOG) and one from the European Organization for Research on Treatment for Cancer (EORTC), of radiation therapy plus adjuvant (as opposed to neoadjuvant) androgen ablation have reported survival gains over radiation therapy alone. In contrast, one neoadjuvant trial from the RTOG failed to show a survival benefit when androgen ablation was added to radiation therapy. In this study, however, androgen ablation was administered for only 4 to 5 months, which may be insufficient. The weight of the evidence to date indicates a true benefit with androgen ablation plus radiation therapy over radiation therapy alone. There are clearly many unanswered questions concerning the optimal timing of androgen ablation and radiation therapy (neoadjuvant versus adjuvant), length of time that androgen ablation should be administered (6 months versus 3 years versus permanent), type of androgen ablation (total androgen ablation or not), and appropriate patient population (definition of high risk). The planned future clinical trials will address many of these issues; however, the full potential of this approach requires an understanding of the fundamental mechanisms involved.

Pathological changes in prostate lesions after androgen manipulation

The number of newly diagnosed cases of prostate cancer has doubled in the past four years because of the aging of the population coupled with growing awareness of the importance of early detection. The issues of clinical understaging and resection limit positivity have led to the development of novel management practices, including neoadjuvant hormonal treatment, which aims to downstage the primary tumour and decrease the positive margin rate before definitive localised treatment (radical prostatectomy or definitive radiation treatment (neoadjuvant)). There is conflicting evidence regarding pathological downstaging, with some studies suggesting benefit and others no benefit of androgen manipulation before radical prostatectomy. The problem might be related to incomplete sampling of the prostates and difficulties associated with the pathological interpretation of morphological changes. The least controversial aspect of neoadjuvant treatment is its impact on surgical margins. Most series have shown that neoadjuvant treatment in clinical T2 tumours is associated with a 20-25% decrease in positive margins in radical prostatectomy specimens. In patients with clinical T3 tumours, the effects of neoadjuvant treatment on positive margins are less clear. Even if some early significant advantages can be observed following hormonal treatment this may not alter the metastatic spread and overall survival rate. Only long term follow up studies evaluating biological and clinical failures, time to progression, and survival will allow definitive conclusions from this approach.