Prostate-specific membrane antigen-positron emission tomography/computed tomography (PSMA-PET/CT)-guided stereotactic ablative body radiotherapy for oligometastatic prostate cancer: a single-institution experience and review of the published literature.

OBJECTIVES: To report the outcomes of stereotactic ablative body radiotherapy (SABR) in men with oligometastatic prostate cancer (PCa) diagnosed on prostate-specific membrane antigen (PSMA)-positron emission tomography/computed tomography (PET/CT), based on a single-institution experience and the published literature. PATIENTS AND METHODS: This was a retrospective cohort study of the first 20 consecutive men with oligometastatic PCa, treated with SABR in a single institution, who had biochemical recurrence after previous curative treatment (surgery/radiotherapy), had no evidence of local recurrence, were not on palliative androgen deprivation therapy (ADT), and had PSMA-PET/CT-confirmed oligometastatic disease (≤3 lesions). These men were treated with SABR to a dose of 30 Gy in three fractions for bone metastases, and 35-40 Gy in five fractions for nodal metastases. The outcomes of interest were: PSA response; local progression-free survival (LPFS); distant progression-free survival (DPFS); and ADT-free survival (ADTFS). A literature review was performed to identify published studies reporting on outcomes of PSMA-PET/CT-guided SABR. RESULTS: In our institutional cohort, 12 men (60%) had a decline in PSA post-SABR. One man had local progression 9.6 months post-SABR, with 12-month LPFS of 93%. Ten men had distant progression outside of their SABR treatment field, confirmed on PSMA-PET/CT, with 12-month DPFS of 62%, of whom four were treated with palliative ADT, two received prostate bed radiotherapy for prostate bed progression (confirmed on magnetic resonance imaging), and four received a further course of SABR (of whom one had further progression and was treated with palliative ADT). At last follow-up, six men (one with local progression and five with distant progression) had received palliative ADT. The 12-month ADTFS was 70%. Men with longer intervals between local curative treatment and SABR had better DPFS (P = 0.03) and ADTFS (P = 0.005). Four additional studies reporting on PSMA-PET/CT-guided SABR for oligometastatic PCa were identified and included in the review, giving a total of 346 patients. PSA decline was reported in 60-70% of men post-SABR. The 2-year LPFS, DPFS and ADTFS rates were 76-100%, 27-52%, and 58-62%, respectively. CONCLUSION: Our results showed that PSMA-PET/CT could have an important role in identifying men with true oligometastatic PCa who would benefit the most from metastases-directed therapy with SABR.

To biopsy or not to biopsy? Outcomes following stereotactic body radiotherapy (SBRT) for biopsy-confirmed versus radiologically-diagnosed primary lung cancer in a single Australian institution.

INTRODUCTION: Obtaining tissue diagnosis for lung cancer can sometimes be difficult and unsafe. We evaluated outcomes of biopsy-confirmed versus radiologically-diagnosed lung cancer treated with stereotactic body radiotherapy (SBRT). METHODS: A single-institutional retrospective cohort of lung cancer patients treated with SBRT between February 2014 and October 2018. Outcomes of interest were: local failure (LF), distant failure (DF), and overall survival (OS). Probability of LF, DF, and OS were estimated using the Kaplan-Meier method. Differences in outcomes between biopsy-confirmed versus radiologically-diagnosed lung cancer were evaluated using the log-rank test. RESULTS: Sixty-five lung lesions in 61 patients were treated with SBRT. Mean age was 75.6 years. Twenty-seven patients (44.3%) were ECOG 2-3. Thirty-nine patients (64%) were radiologically-diagnosed. There were five cases of LF observed at median of 12.8 months post-SBRT and 12-month LF-free survival was 96% (95% CI, 86-99%), with no differences between groups (p = 0.1). Sixteen patients developed DF, with 12-month DF-free survival of 84% (95% CI, 71-91%), and no difference between groups (p = 0.06). Sixteen deaths were reported at a median of 12.5 months post-SBRT, with 12-month OS of 85% (95% CI, 73-92%), and no differences between study groups (p = 0.5). No grade 3 toxicities were reported. CONCLUSION: The oncological outcomes were similar in patients with early lung cancer treated with SBRT with or without biopsy-confirmation. In situations where tissue diagnosis is not feasible or unsafe, it is not unreasonable to offer SBRT based on clinical and radiological suspicion following multidisciplinary discussions.

A Prospective Trial Demonstrating the Benefit of Personalized Selection Of Breath-Hold Technique for Upper-Abdominal Radiation Therapy Using the Active Breathing Coordinator.

PURPOSE: For upper abdominal tumors, our institutional-standard motion reduction method is the expiration breath-hold (EBH) technique, using Active Breathing Coordinator (ABC). However, an individual patient's breath-hold (BH) reproducibility (RBH) may be improved in deep inspiration or inspiration breath-hold (DIBH or IBH). This trial compared the tumor position RBH, stability (SBH), and breath-hold time (TBH) of 3 BH methods, using ABC, to personalize the selection of technique, by using a preplanning screening assessment. METHODS AND MATERIALS: We invited patients planned for upper abdominal radiation therapy (kidney, pancreas, liver, or adrenal gland) to participate in this prospective trial. We conducted ABC education with the study participants, who then attempted EBH, DIBH, and IBH in randomized order. During 5 consecutive BH's for each method, we acquire kV fluoroscopy images of the diaphragm. We personalized the BH technique selection according to a decision matrix. We analyzed the EBH and the personalized technique cohort mean RBH and SBH. RESULTS: Between May 2019 and March 2020, we recruited 19 participants. Median age of participants was 68 years (range 32-81). Tumor sites included kidney (n = 1), adrenal gland (n = 5) and liver (n = 14). We excluded 1 participant due to poor BH compliance, leaving 270 images from 18 participants for analysis. Mean TBH was 22.1, 23.9, and 24.2 seconds for EBH, DIBH, and IBH respectively. Screening selected EBH for 44% (n = 8), IBH for 39% (n = 7), and DIBH for 17% (n = 3) of participants. The mean RBH was superior at 0.92 mm (0.79 mm SD) for the personalized technique, compared with EBH of 1.79 mm (1.49 mm SD) (P = .016). Preplanned subset analysis of participants whose personalized technique was not EBH showed improved mean RBH of 0.63 mm (0.29 mm SD) compared with their EBH RBH of 2.2 mm (1.7 mm SD) (P = .011). CONCLUSIONS: In 56% of participants, DIBH or IBH demonstrated superior RBH compared with EBH. Personalised BH screening can inform selection of an ABC BH method which provides optimal RBH with improved TBH for an individual's planning and treatment course.

Protocol of a study investigating breath-hold techniques for upper-abdominal radiation therapy (BURDIE): addressing the challenge of a moving target.

BACKGROUND: Radiation therapy to upper abdominal sites is technically challenging due to motion of tumors and surrounding organs resulting from normal respiration. Breath-hold, using an Active Breathing Coordinator is one strategy used to reduce motion in these tumor sites. Though widely used, no studies have prospectively compared the different breath-hold techniques (inspiration, deep-inspiration and expiration) using ABC in the same patient cohort. METHODS: Patients planned for radiation therapy to upper abdominal tumors are invited to participate in this prospective study. Participants attempt three breath hold techniques: inspiration, deep-inspiration and expiration breath-hold, in random order. kV fluoroscopy images of the dome of diaphragm are taken of five consecutive breath-holds in each technique. Reproducibility and stability of tumour position are measured, and used to select the technique with which to proceed to planning and treatment. Reproducibility at planning and each treatment fraction is measured, along with breath hold time, treatment efficiency and patient experience. DISCUSSION: The screening method was validated after the first three participants. This screening process may be able to select the best breath-hold technique for an individual, which may lead to improved reproducibility. The screening process is being piloted as a prospective clinical trial. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR): 12618001691235. Registered 12th October 2018. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376109&isReview=true .