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For locally advanced cervical cancer (LACC), anatomy correspondence with and without BT applicator needs to be quantified to merge the delivered doses of external beam radiation therapy (EBRT) and brachytherapy (BT). This study proposed and evaluated different deformable image registration (DIR) methods for this application. Twenty patients who underwent EBRT and BT for LACC were retrospectively analyzed. Each patient had a pre-BT CT at EBRT boost (without applicator) and a CT and MRI at BT (with applicator). The evaluated DIR methods were the diffeomorphic Demons, commercial intensity and hybrid methods, and three different biomechanical models. The biomechanical models considered different boundary conditions (BCs). The impact of the BT devices insertion on the anatomy was quantified. DIR method performances were quantified using geometric criteria between the original and deformed contours. The BT dose was deformed toward the pre-CT BT by each DIR method. The impact of boundary conditions to drive the biomechanical model was evaluated based on the deformation vector field and dose differences. The GEC-ESTRO guideline dose indices were reported. Large organ displacements, deformations, and volume variations were observed between the pre-BT and BT anatomies. Rigid registration and intensity-based DIR resulted in poor geometric accuracy with mean Dice similarity coefficient (DSC) inferior to 0.57, 0.63, 0.42, 0.32, and 0.43 for the rectum, bladder, vagina, cervix and uterus, respectively. Biomechanical models provided a mean DSC of 0.96 for all the organs. By considering the cervix-uterus as one single structure, biomechanical models provided a mean DSC of 0.88 and 0.94 for the cervix and uterus, respectively. The deformed doses were represented for each DIR method. Caution should be used when performing DIR for this application as standard techniques may have unacceptable results. The biomechanical model with the cervix-uterus as one structure provided the most realistic deformations to propagate the BT dose toward the EBRT boost anatomy. [ABSTRACT FROM AUTHOR]

Background: Chemotherapy has emerged as a standard treatment in patients with castration-refractory prostate cancer (CRPC). Consensus criteria are available to define response in CRPC as at least a 50% decline in serum prostate-specific antigen (PSA) confirmed 4 weeks later. The objective of this work was to study early serum PSA changes in patients under chemotherapy and to correlate these changes with subsequent response assessment. Patients and methods: Serum PSA levels were monitored every 3 weeks in 79 patients with CRPC treated with chemotherapy and a time course of serum PSA levels was obtained. Correlation with response was studied. Results: According to consensus criteria, 21 (40%) and 20 (38%) patients achieved a PSA response and stabilization, respectively, after first-line chemotherapy. Among patients who achieved either a response or a stabilization, 8 of 41 (20%) had a serum PSA rise during the first 8 weeks of chemotherapy, followed by a subsequent decline in serum PSA. The same observation was made in patients receiving second-line chemotherapy: 6 of 20 patients achieving a response or stabilization had an initial serum PSA rise. The postchemotherapy increase in serum PSA could reach more than twice the baseline value. The duration of the PSA surge ranged from 1 to 8 weeks. When considering responders only, 6 of 30 (20%) had a postchemotherapy serum PSA surge, followed by a drop. Conclusion: Postchemotherapy PSA surges occur not infrequently in patients with CRPC who respond to chemotherapy. Physicians should be aware of this effect to avoid inadequate early discontinuation of chemotherapy. [ABSTRACT FROM AUTHOR]