Hypofractionated versus conventionally fractionated image-guided volumetric-modulated arc radiotherapy for localized prostate cancer: a phase II randomized trial from China.

PURPOSE: To determine the safety of hypofractionated imaging-guided (IG) volumetric-modulated arc radiotherapy (IG-VMAT; 70 Gy/28 fractions over 5.5 weeks) versus conventionally fractionated regimen (IG-VMAT; 80 Gy/40 fractions over 8 weeks) in Chinese patients with localized prostate cancer. METHOD: In this randomized non-comparative phase II trial, 92 patients with localized prostate cancer were assigned to receive either hypofractionated IG-VMAT (HFRT; 70 Gy/2.5Gy/28f) or conventionally fractionated IG-VMAT (CFRT; 80 Gy/2Gy/40f). Primary endpoint was grade 2 or higher late gastrointestinal (GI) and genitourinary (GU) toxicity at 2 years. The GI/GU toxicity and biochemical relapse-free survival (bRFS) were compared between the two treatment groups. RESULTS: Median follow-up was 26 months. The incidence of grade 2 or higher late GI/GU toxicity was low in both groups; the 5-year cumulative incidence of Radiation Therapy Oncology Group grade 2 or higher GI/GU toxicity at 2 years was 7.6% with HFRT versus 10.3% with CFRT (P = 0.707). Biochemical control was not significantly different between the two groups; the 2-year bRFS was 94.6% for HFRT versus 95.0% for CFRT (P = 0.704). CONCLUSION: Hypofractionated IG-VMAT appears to be equivalent to conventionally fractionated IG-VMAT in terms of toxicity in Chinese patients with localized prostate cancer.

Radiomics of Multiparametric MRI to Predict Biochemical Recurrence of Localized Prostate Cancer After Radiation Therapy.

Background: To identify multiparametric magnetic resonance imaging (mp-MRI)-based radiomics features as prognostic factors in patients with localized prostate cancer after radiotherapy. Methods:From 2011 to 2016, a total of 91 consecutive patients with T1-4N0M0 prostate cancer were identified and divided into two cohorts for an adaptive boosting (Adaboost) model (training cohort: n = 73; test cohort: n = 18). All patients were treated with neoadjuvant endocrine therapy followed by radiotherapy. The optimal feature set, identified through an Inception-Resnet v2 network, consisted of a combination of T1, T2, and diffusion-weighted imaging (DWI) MR series. Through a Wilcoxon sign rank test, a total of 45 distinct signatures were extracted from 1,536 radiomics features and used in our Adaboost model. Results:Among 91 patients, 29 (32%) were classified as biochemical recurrence (BCR) and 62 (68%) as non-BCR. Once trained, the model demonstrated a predictive classification accuracy of 50.0 and 86.1% respectively for BCR and non-BCR groups on our test samples. The overall classification accuracy of the test cohort was 74.1%. The highest classification accuracy was 77.8% between three-fold cross-validation. The areas under the curve (AUC) of receiver operating characteristic curve (ROC) indices for the training and test cohorts were 0.99 and 0.73, respectively. Conclusion:The potential of multiparametric MRI-based radiomics to predict the BCR of localized prostate cancer patients was demonstrated in this manuscript. This analysis provided additional prognostic factors based on routine MR images and holds the potential to contribute to precision medicine and inform treatment management.