title: The predictive role of ADC values in prostate cancer patients treated with carbon-ion radiotherapy: initial clinical experience at Shanghai Proton and Heavy Ion Center (SPHIC).
abstract: OBJECTIVE
  The aim of our study was to investigate the predictive role of apparent diffusion coefficient (ADC) values in evaluating for therapeutic changes from carbon-ion radiotherapy (CIRT) in prostate cancer patients.
  
  
  METHODS
  Thirty-one patients with prostate cancer treated with CIRT were enrolled in this retrospective study. Diffusion-weighted imaging (DWI) at 3-T was performed before and after CIRT. Before and after treatment, ADC values were measured in the tumors and in the benign tissues of the prostate, and serum prostate-specific antigen (PSA) levels were also assessed. We divided the patients into two groups: PSA response (PSA declines ≥50 %) and non-PSA response group (PSA declines <50 %).
  
  
  RESULTS
  After CIRT treatment, the mean ADC value of the tumors (1.23 × 10(-3)mm(2)/s) was significantly increased as compared with the pretreatment value (1.07 × 10(-3)mm(2)/s) (p < 0.001), whereas the ADC values of the benign tissues after treatment did not significantly increase compared with the pretreatment values (p = 0.235). The mean PSA level was significantly reduced from 2.027 ng/mL before treatment to 0.822 ng/mL, respectively, after treatment (p = 0.0063). The mean of ADC changes in PSA response group before and after CIRT was significantly higher than that in non-PSA response group (∆ADC value: 0.217 vs 0.097 × 10(-3)mm(2)/s, p = 0.0229), and the rate of patients with PSA response was higher in the high ∆ADC group (∆ADC ≥ 0.10) than in the low ∆ADC group (∆ADC < 0.10) (72.7 and 33.3 %, respectively), but marginally significant (p = 0.056). Additionally, the baseline tumor ADC values revealed a negative correlation with changes in PSA levels after treatment (correlation coefficient, ρ = -0.524; p = 0.0025).
  
  
  CONCLUSIONS
  Our preliminary results suggest that ADC vales measurement may be a useful imaging biomarker for prediction and early assessment of therapeutic response of prostate cancer to CIRT.
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, No. 4365 Kang Xin Road, Shanghai, 201318, China.
authors.forename: Wei-Xiang
authors.initials: WX
authors.lastname: Qi
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, No. 4365 Kang Xin Road, Shanghai, 201318, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, No. 4365 Kang Xin Road, Shanghai, 201318, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, No. 4365 Kang Xin road, Shanghai, 201321, Shanghai, China.
authors.forename: Xiao-Meng
authors.initials: XM
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Shanghai Proton and Heavy Ion Center, No. 4365 Kang Xin Road, Shanghai, 201318, China.
authors.forename: Guang-Yuan
authors.initials: GY
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Shanghai Proton and Heavy Ion Center, No. 4365 Kang Xin Road, Shanghai, 201318, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wu
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, No. 4365 Kang Xin Road, Shanghai, 201318, China.
authors.forename: Jiade J
authors.initials: JJ
authors.lastname: Lu
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, No. 4365 Kang Xin Road, Shanghai, 201318, China.
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Jiang
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, No. 4365 Kang Xin road, Shanghai, 201321, Shanghai, China. fushen2014@sina.com.
authors.forename: Shen
authors.initials: S
authors.lastname: Fu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002681:China; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011878:Radiotherapy / Q000379:methods; D012189:Retrospective Studies
keywords: Carbon-ion radiotherapy; Diffusion-weighted MRI; Prostate cancer; Prostate-specific antigen