68Ga-PSMA-PET/CT-based radiosurgery and stereotactic body radiotherapy for oligometastatic prostate cancer.

BACKGROUND: Androgen deprivation therapy (ADT) remains the standard therapy for patients with oligometastatic prostate cancer (OMPC). Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT)-based stereotactic body radiotherapy (SBRT) is emerging as an alternative option to postpone starting ADT and its associated side effects including the development of drug resistance. The aim of this study was to determine progression free-survival (PFS) and treatment failure free-survival (TFFS) after PSMA-PET/CT-based SBRT in OMPC patients. The efficacy and safety of single fraction radiosurgery (SFRS) and ADT delay were investigated. METHODS: Patients with ≤5 metastases from OMPC, with/without ADT treated with PSMA-PET/CT-based SBRT were retrospectively analyzed. PFS and TFFS were primary endpoints. Secondary endpoints were local control (LC), overall survival (OS) and ADT-free survival (ADTFS). RESULTS: Fifty patients with a total of 75 metastases detected by PSMA-PET/CT were analyzed. At the time of SBRT, 70% of patients were castration-sensitive. Overall, 80% of metastases were treated with SFRS (median dose 20 Gy, range: 16-25). After median follow-up of 34 months (range: 5-70) median PFS and TFFS were 12 months (range: 2-63) and 14 months (range: 2-70), respectively. Thirty-two (64%) patients had repeat oligometastatic disease. Twenty-four (48%) patients with progression underwent second SBRT course. Two-year LC after SFRS was 96%. Grade 1 and 2 toxicity occurred in 3 (6%) and 1 (2%) patients, respectively. ADTFS and OS rates at 2-years were 60.5% and 100%, respectively. In multivariate analysis, TFFS significantly improved in patients with time to first metastasis (TTM) >36 months (p = 0.01) and PSA before SBRT ≤1 ng/ml (p = 0.03). CONCLUSION: For patients with OMPC, SBRT might be used as an alternative to ADT. This way, the start/escalation of palliative ADT and its side effects can be deferred. Metastases treated with PSMA-PET/CT-based SFRS reached excellent LC with minimal toxicity. Low PSA levels and longer TTM predict elongated TFFS.

Outcomes and relapse patterns of stage IB grade 2 or 3 endometrial cancer treated with adjuvant vaginal brachytherapy.

INTRODUCTION: Risk factors for pelvic recurrence in early stage endometrial cancer are poorly understood. We sought to describe outcomes, patterns of failure, and risk factors for recurrence among patients with grade 2-3 endometrial cancer with deep myometrial invasion who were treated with vaginal brachytherapy as sole adjuvant therapy after hysterectomy and lymph node dissection. METHODS: We retrospectively reviewed the records of stage I patients with grade 2-3 endometrioid histology and ≥50% myometrial invasion treated at an academic institution from January 2005 to December 2017. Only patients with endometrioid histology were included. Mixed histologies, including papillary serous or clear cell components, were excluded. Further exclusion criteria were International Federation of Gynecology and Obstetrics stage IB grade 1 patients, follow-up time less than 3 months, receipt of pelvic irradiation or any form of systemic therapy (chemotherapy, aromatase inhibitor). Overall survival, disease-free survival, and pelvic recurrence-free survival were calculated with Kaplan-Meier methods. Multivariable Cox proportional hazards regression was used to analyze factors associated with overall survival and disease-free survival. RESULTS: Among 131 consecutive patients identified, 111 (85%) patients met the inclusion criteria. The majority (98.2%) underwent lymph node dissection with ≥10 lymph nodes removed in 78.9%. With a median follow-up of 36 months (IQR 12-70 months), the 3-year overall survival, disease-free survival, and pelvic recurrence-free survival were 89.6%, 90.1%, and 92.8%, respectively. Histologic grade 3, older age, and lymphovascular invasion were not associated with inferior outcomes; however, lower uterine segment involvement (p=0.031), tumor size >4 cm (p=0.024), and <10 lymph nodes removed (p=0.032) were associated with reduced disease-free survival on multivariable analysis. Pelvic recurrence occurred in 12 (11%) patients, most often in the setting of synchronous distant disease (n=9), and was significantly more likely with lower uterine segment involvement. CONCLUSION: Among patients with stage IB grade 2-3 endometrial cancer treated with vaginal brachytherapy, the risk factors for recurrence (larger tumor size and lower uterine segment involvement) in conjunction with established risk factors (high grade, ≥50% myometrial invasion, and lymphovascular invasion) may identify a group of high-risk patients who might benefit from pelvic radiotherapy.