Post-prostatectomy Radiotherapy

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Hong Kong J Radiol 2013;16(Suppl):S39-43

Patients with localised prostate cancer can be cured with radical prostatectomy alone. Nevertheless, many of them may develop local failure due to positive surgical margins or residual disease from extraprostatic extension (pT3), which necessitates post-prostatectomy radiotherapy to the prostatic fossa as either adjuvant radiotherapy (ART) or salvage radiotherapy (SRT). Three randomised studies have addressed the role of ART. The European Organisation for Research and Treatment of Cancer demonstrated the superiority of ART over observation alone, in terms of biochemical progression-free survival, for men with positive margins or pT3 prostate cancer after radical prostatectomy. Subsequently, a German study also showed improvement of biochemical control by about 20% with ART. In North America, the SWOG 8794 trial, which enrolled similar patients, reported an improvement in metastasis-free survival with ART after a median follow-up of 12 years. However, immediate ART may not benefit all patients and can cause serious side-effects. It is uncertain whether ART should be given immediately after surgery or only when there is a rising prostate-specific antigen level after surgery, indicating active cancer. The role of androgen-deprivation therapy (ADT) with SRT/ART also remains unclear. Further randomised controlled trials are under way and their results may provide further information on the optimum timing of SRT and ADT. The challenges of post-prostatectomy radiotherapy include difficulty in determining the clinical target volume, and its close proximity to the rectum and bladder. New radiotherapy techniques such as intensity-modulated radiotherapy and volumetric-modulated arc therapy have been introduced to improve accuracy and efficiency in the delivery of post-prostatectomy radiotherapy. The results of using intensitymodulated radiotherapy as salvage radiotherapy in Tuen Mun Hospital, Hong Kong have been promising in a group of selected patients.





單獨使用根治性前列腺切除術可以治癒患有局部性前列腺癌的病人。然而這些病人當中,很多會因手術切除邊緣陽性或前列腺外擴散(pT3)的殘留癌病而出現局部治療失敗,需要於前列腺窩進行前列腺切除術後放射治療,作為輔助放療或挽救性放療。三項隨機試驗研究了輔助放療的角色。EORTC研究證明在根治性前列腺切除術後有邊緣陽性或pT3的前列腺癌男性病人中,輔助放療對病人生化無惡化存活的作用,較單獨採取觀察法為佳。其後一項德國研究亦顯示,採用輔助放療對生化控制有約20%的改善。在北美的SWOG 8794試驗納入了相若的病人,在中位數為12年的跟進後,報告表示採用輔助放療對無轉移存活有改善。然而,即時採用輔助放療未必適合所有病人,並可能引致嚴重副作用。目前未能確定應否在手術後立即採用輔助放療,抑或只有在手術後,當前列腺特異性抗原水平上升顯示有活躍癌症時,才採用輔助放療。與挽救性放療/輔助放療同時使用雄激素阻斷治療的角色亦未明確。更多隨機對照試驗正在進行中,研究結果可能會提供有關使用挽救性放療與雄激素阻斷治療最佳時機的進一步資料。前列腺切除術後放療所面對的挑戰包括:難以確定臨床目標體積,以及其位置與直腸和膀胱相接近。新的放療技術,例如如強度調控放射治療和體積調控弧形治療已經推出,以改善前列腺切除術後放療的準確性和效率。在屯門醫院一組特選病人中使用強度調控放射治療作挽救性放療的結果令人鼓舞。