Our purpose was to determine whether there is a clinical benefit to add lower-limb imaging in 68 Ga-labeled prostate-specific membrane antigen (PSMA) PET/CT scans for patients with prostate cancer. Methods: In total, 701 patients with prostate cancer who underwent 68 Ga-PSMA PET/CT were evaluated retrospectively. All patients underwent additional lower-limb imaging. Images were reanalyzed by experienced nuclear medicine physicians, and metastatic sites were documented. The prostate-specific antigen (PSA) level and Gleason score were also compared with 68 Ga-PSMA PET/CT findings. Results: In 601 patients (85.7%), at least 1 tumoral lesion was observed on 68 Ga-PSMA PET/CT. The number of patients with bone metastasis in 2 forms was 278 patients (39.6%); 108 (15.4%) were oligometastatic (,4 metastases) and 170 (24.2%) were multimetastatic (≥4 metastases). In lower-limb imaging, bone metastasis was detected in 61 patients (8.7%), the specific locations of which were as follows: middle-distal femur (n 5 54), tibia (n 5 19), fibula (n 5 24), and calcaneus (n 5 1). Lower-limb metastasis was detected mostly in symptom-positive patients (70.1%) but in only 4% of the symptom-negative group. All patients with lower-extremity metastasis also had multiple bone metastases shown on limited whole-body 68 Ga-PSMA PET/CT. The median PSA level was significantly higher in multimetastatic patients with lower-limb metastasis than in those without lower-limb metastasis (P , 0.001, Mann-Whitney U test), but no statistical differences was found in terms of Gleason score (χ 2 5 0.042, P 5 0.837). According to receiver-operatingcharacteristic analysis, PSA has a good predictive value for detecting lower-limb metastasis, with 76.6% sensitivity and 72% specificity (using a reference cutoff PSA level of 24 ng/mL [area under the curve, 0.81; 95% confidence interval, 0.74-0.87]). Conclusion: Lower-limb imaging did not change the metastatic status of disease or significantly affect the therapeutic approach. However, if multimetastatic patients present relevant symptoms for lower-limb metastasis, it could be beneficial to consider including lower-limb imaging for possible palliative therapies.
Background
Peptide receptor radionuclide therapy and selective internal radiation therapy are effective radionuclide therapy modalities for unresectable metastatic neuroendocrine tumor patients that cannot be controlled with somatostatin analogs. The present study is intended to evaluate the therapeutic efficacy and toxicity of the combined therapy of selective internal radiation therapy and peptide receptor radionuclide therapy and stand-alone selective internal radiation therapy in patients with neuroendocrine tumor, a liver-dominant disease.
Methods
This cohort consists of 27 patients with metastatic neuroendocrine tumor and liver-dominant disease. They were grouped as the patients who were treated with selective internal radiation therapy for unresectable liver metastasis (n = 15) and the patients who received a combination of selective internal radiation therapy and peptide receptor radionuclide therapy (n = 12) for hepatic and extrahepatic metastasis. Treatment efficacy and treatment-associated toxicity were retrospectively assessed in both groups.
Results
The objective treatment response and stable disease were found in 13 patients (86.6%) in the selective internal radiation therapy group and eight patients (66.6%) in the selective internal radiation therapy + peptide receptor radionuclide therapy group. The median overall survival rate was found to be 34.9 months, in the selective internal radiation therapy group and 67.5 months in the selective internal radiation therapy + peptide receptor radionuclide therapy group (P = 0.217). The median progression-free survival data was not reached, and the mean values of progression-free survival were 53.1 ± 9.9 months in the selective internal radiation therapy group, and 27.2 ± 5.9 months in the selective internal radiation therapy + peptide receptor radionuclide therapy group (P = 0.561). Temporary lymphopenia was the most common side effect. Grade 1–2 hepatotoxicity was observed to be 6.6% in the selective internal radiation therapy group, while it was not observed in selective internal radiation therapy + peptide receptor radionuclide therapy group.
Conclusions
In the neuroendocrine tumors with liver-dominant metastatic disease, personalized selective internal radiation therapy and peptide receptor radionuclide therapy and their combinations result in increased survival rates. Selective internal radiation therapy alone could be an effective treatment in patients with liver-limited and -dominant disease.
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