Journal of Radiation Research, 2012, 53, 727–734 doi: 10.1093/jrr/rrs034 Advance Access Publication 10 July 2012 Salvage radiotherapy after radical prostatectomy: outcomes and prognostic factors especially focusing on pathological findings Satoko HAYASHI *,1, Keiji HAYASHI 1, Ryo-ichi YOSHIMURA 1, Hitoshi MASUDA 2, Kazunori KIHARA 2 and Hitoshi SHIBUYA 1 1Department of Radiation Oncology, Tokyo Medical and Dental University, Graduate School of Medical and Dental Sciences, Tokyo 113-8519, Japan 2Department of Urology, Tokyo Medical and Dental University, Graduate School of Medical and Dental Sciences, Tokyo 113-8519, Japan *Corresponding author. Tel: +81-3-5803-5311; Fax: +81-3-5803-0147; Email: arimrad@tmd.ac.jp (Received 12 February 2012; revised 25 April 2012; accepted 18 May 2012) External beam radiotherapy is a potential salvage or adjuvant therapy after radical prostatectomy (RP). The purpose of this study was to investigate the treatment outcome of salvage radiotherapy (RT) following RP for clinically localized prostate cancer and to identify factors that may predict the outcome of salvage RT. Between 2000 and 2006, 41 patients received salvage RT because of increasing prostate-specific antigen (PSA) levels following an RP for clinically localized prostate cancer. All the patients received conformal radiotherapy to the prostate bed. The prescribed radiation dose was 60–70 Gy in 26–35 fractions. The overall 5-year biochemical disease-free survival rate was 38%. A multivariate analysis showed that the fol- lowing pathological findings of the surgical specimen were significantly associated with biochemical failure following salvage RT: a high Gleason score, a negative surgical margin, seminal vesicle invasion, lymphatic vessel invasion and negative vascular invasion. Among these factors, lymphatic vessel invasion was the stron- gest predictor. In conclusion, the pathological features affected the outcome of salvage RT following RP. Lymphatic vessel invasion was strongly associated with the risk of biochemical failure despite salvage RT. Meanwhile, vascular invasion was not a significant hazardous factor. Keywords: prostatectomy; salvage radiotherapy; prostate cancer; prostate-specific antigen; pathological findings INTRODUCTION Prostate cancer is the most commonly diagnosed malig- nant tumor in men because of the widespread use of prostate-specific antigen (PSA) testing. Prostate cancer is also the second leading cause of death from cancer in the USA [1]. Many treatments have been developed for clin- ically localized prostate cancer, resulting in improved treatment outcomes; for example, radical prostatectomy (RP), external beam radiotherapy, brachytherapy, high- intensity focused ultrasound and cryotherapy have all been used to treat prostate cancer. RP is widely used as a primary treatment in patients with localized prostate cancer [2]. Despite the effectiveness of RP, approximately one-third of patients experience biochemical failure within 10 years of undergoing their surgery [3]. Biochemical failure is associated with increases in the rates of distant metastasis and death [3, 4]. The median intervals from biochemical failure to distant metastasis and from metas- tasis to death were reported to be 8 years and 5 years, re- spectively [3]. External beam radiotherapy (RT) is a potential salvage or adjuvant therapy after RP. The addition of RT and/or hormonal therapy for patients with biochemical failure after surgery has been reported to lower the risk of an adverse outcome [4]. Although salvage RT is effective for biochem- ical control, the 4- or 5-year biochemical disease-free sur- vival (bDFS) rates after RT have been reported to be 46– 60% [5–7]. Many previous studies have reported outcome predictors for salvage or adjuvant RT. Clinical factors, such as the interval from the salvage RT to biochemical failure, the PSA doubling time (PSA-DT), and the preradiotherapy © The Author 2012. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Therapeutic Radiology and Oncology. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.