Salvage Radiotherapy to the Prostatic Fossa Using Volumetric-modulated Arc Therapy: Early Results

Full Article

EKC Lee, KK Yuen, WH Mui, GML Law, CMM Lui, MKH Chan, FCS Wong, SY Tung

Hong Kong J Radiol 2013;16:191-7

DOI: 10.12809/hkjr1313173

Objectives: Volumetric-modulated arc therapy (VMAT) is better than intensity-modulated radiotherapy (IMRT) in terms of its plan qualities and efficiency for the treatment of prostate cancer. It remains unclear whether its use in salvage radiotherapy to prostatic fossae is safe and effective. Herein we report the dosimetric and clinical results of salvage radiotherapy to prostatic fossae using VMAT.

Methods: Fifteen consecutive patients with a rising prostate-specific antigen after radical prostatectomy in our institution received salvage radiotherapy using VMAT. Prostate-specific antigen control and acute toxicities within 1 year after treatment were retrospectively reviewed. For comparison, IMRT plans were also generated for 12 of these patients and the quality of these plans in terms of organ-at-risk sparing (volume of bladder and rectum receiving 60 and 70 Gy), target coverage (conformation number and the prescribed dose of D90), and the number of monitor units.

Results: After salvage radiotherapy using VMAT, all patients had a decrease in their prostate-specific antigen with a complete response rate of 87%. The recorded toxicities were rectal bleeding, tenesmus, urinary frequency, nocturia, and urinary incontinence. After a median follow-up of 20 months, two patients endured treatment failure. There was no significant difference between the VMAT and IMRT plans in terms of quality. The mean number of monitor units by VMAT (488) was significantly smaller than that used by IMRT (519) [p < 0.001]. The mean beam-on time was 171 (range, 92-228) seconds with treatment delivered by VMAT.

Conclusions: It is efficient, effective, and safe to use VMAT as salvage radiotherapy to the prostatic fossa.







結果:使用VMAT作挽救性放射治療後,所有患者的PSA水平均有減少,有87%患者達至完全緩解。患者的毒性反應有直腸出血、裡急後重、尿頻、夜尿和尿失禁。隨訪期中位數20個月後,兩名病人的治療失敗。VMAT和IMRT計劃在質量方面沒有顯著差異。VMAT(488)的平均機器跳數明顯少於IMRT(519)(p < 0.001)。VMAT的平均束治療時間為171秒(介乎92-228秒)。