Highly hypofractionated intensity-modulated radiation therapy for nonmetastatic prostate cancer with a simultaneous integrated boost to intraprostatic lesions: a planning study.

PURPOSE: The purpose of this planning study was to develop an acceptable technique for highly hypofractionated intensity-modulated radiation therapy using simultaneous integrated boost technique (SIB-hHF-RT) for nonmetastatic National Comprehensive Cancer Network high-risk prostate cancer. MATERIALS AND METHODS: We created SIB-hHF-RT plans for 14 nonmetastatic prostate cancer patients with MRI-detectable intraprostatic lesions (IPLs) and without intestines locating close to the seminal vesicle and prostate. We prescribed 57 Gy for IPLs and 54 Gy for the remainder of planning target volume (PTV) in 15 fractions. The IPLs were contoured based on magnetic resonance imaging, and PTV was generated by adding 6-8-mm margins to the clinical target volume. For the dose-volume constraints of organs at risk (OARs), the same constraints as 54 Gy plans were used so as not to increase the toxicity. RESULTS: All created plans fulfilled the dose-volume constraints of all targets and OARs. The median estimated beam-on time was 108.5 s. For patient-specific quality assurance, the global gamma passing rates (3%/2 mm) with 10% dose threshold criteria were greater than 93% in all cases and greater than 95% in 11 cases. CONCLUSION: SIB-hHF-RT plans were developed that fulfill the acceptable dose-volume constraints and pass patient-specific quality assurance. We believe these plans can be applied to selected patients with nonmetastatic prostate cancer.

Increased risk of disease progression in younger men: Analysis of factors predicting biochemical failure and castration-resistant prostate cancer after high-dose intensity-modulated radiation therapy for nonmetastatic prostate cancer.

BACKGROUND: The aim of this study was to investigate the clinical significance of the effect of age on disease control in men who received high-dose intensity-modulated radiation therapy (IMRT) for nonmetastatic prostate cancer (NMPCa). METHODS: NMPCa patients with favorable intermediate to very high-risk features (National Comprehensive Cancer Network risk classification) treated with IMRT at our institution between September 2000 and May 2011 were analyzed retrospectively. Treatment consisted of high-dose IMRT (74-78 Gy/37-39 fractions) combined with 6 months of neoadjuvant hormonal therapy. Multivariable analysis using Fine and Gray's regression model was performed to evaluate whether age at initiation of IMRT was associated with biochemical failure (BF) and castration-resistant prostate cancer (CRPC) progression. RESULTS: A total of 367 patients were analyzed. The median follow-up period was 8.8 years after IMRT. The 5- and 10-year BF rates were 22.1 and 31.7%, and those of CRPC rates were 4.5 and 12.6%, respectively. Multivariable analysis revealed that a younger age (cut-off: 70 years old) at the initiation of IMRT was significantly correlated with both a higher BF rate (hazard ratio: 1.691, P= 0.0064) and higher CRPC rate (hazard ratio: 2.579, P = 0.0079). CONCLUSIONS: Younger men with NMPCa had increased risks of BF and CRPC after high-dose IMRT, and may benefit from more intensive treatments. Our findings should be further tested in prospective studies.