11C-Choline Positron Emission Tomography-Detected Prostate Cancer Thoracic Metastases

Abstract

<h3>Purpose/Objective(s)</h3> Prostate cancer metastasis to the chest is considered a poor prognostic indicator but is not well-described in the era of molecular imaging. We evaluate the radiographic features, management, and outcomes associated with prostate cancer thoracic metastases detected by ¹¹C-choline positron emission tomography/computed tomography (PET/CT). <h3>Materials/Methods</h3> A prospectively maintained database of 6,118 prostate cancer patients with ¹¹C-choline PET/CT findings was used to identify thoracic metastases detected from 2011 to 2021. Biopsy confirmation was not required, but patients with a negative biopsy were excluded from analysis. Patient, disease, and treatment characteristics were identified and analyzed for their association with outcomes. <h3>Results</h3> Sixty-seven patients (1.1% of those in the database) were included with a median follow-up of 45 months (IQR: 17-57.5) from metastasis detection. Primary local treatment was radical prostatectomy in 36 (55.2%) patients and radiotherapy in 21 (31.3%). Thirty-seven patients (55.2%) had histologic confirmation. Median interval from initial diagnosis to thoracic metastasis detection was 66 months (IQR: 38-107). Thirty-nine patients (58.2%) were oligometastatic (≤5 lesions) and 23 (34.3%) had previously diagnosed extrapulmonary metastases. Lesions were more often in the lung parenchyma (80.5%) than mediastinum (9.8%), hila (8.5%), or pleura (1.2%). Median greatest dimension was 1.0 cm (IQR: 0.8-1.3). Eight patients (11.9%) had lesions detectable on CT without PET avidity, five of whom had histologic confirmation. Median SUV_max was 3.3 (IQR: 2.5-4.4) for all ¹¹C-choline PET/CT-avid lesions and 3.9 (IQR: 2.5-4.6) in histologically confirmed lesions. Fifty-seven patients (85.1%) were managed with systemic therapy. Eighteen lesions in 17 patients were managed with local therapy, 15 surgically and 3 with radiotherapy. Among the 39 patients with oligometastatic disease, median time to subsequent radiographic progression was 28 months compared to 14 months in those with widely disseminated disease. Median time to progression in the 17 men receiving metastasis-directed therapy was 33 months, despite a lower rate (52.9%) of systemic therapy use in this group. Forty-nine (73.1%) patients were alive at last follow-up. <h3>Conclusion</h3> We provide the largest single institution report to date of patients with ¹¹C-choline PET/CT-detected prostate cancer thoracic metastases. In well-selected men, metastasis-directed therapy may delay time to radiographic progression and initiation of systemic therapy. At the time of detection, a third of patients have diffuse pulmonary involvement. Despite this finding, survival outcomes remain encouraging with nearly three-quarters of patients alive at a median follow-up of 45 months. Efforts are ongoing to identify clinicopathologic and molecular characteristics which may guide management in this population.