Ten-year experience of bone SBRT in breast cancer: analysis of predictive factors of effectiveness.

PURPOSE: Data on the benefit of stereotactic body radiation therapy (SBRT) in patients with breast cancer (BC) and bone metastases remain limited. The purpose of this study is to report our 10-year experience of bone SBRT, analyzing toxicity and prognostic factors for local control (LC); progression-free survival, and overall survival (OS). METHODS/PATIENTS: We analyzed all spine and non-spine bone SBRT performed in patients with BC during the 2012-2022 period at our institution. Treatments carried out with ablative intent in stereotactic conditions with dose/fraction ≥ 5 Gy in 5 or fewer sessions were considered. Demographic, treatment, and toxicity data were recorded according to CTCAEv4. Risk factors were assessed through univariate and multivariate analysis by Cox regression. RESULTS: 60 bone SBRT treatments were performed during the study period. 75% were spine SBRT and 25% were non-spine SBRT (median BED4Gy was 80 Gy4). The median age was 52.5 years (34-79). The median tumor volume was 2.9 cm3 (0.5-39.4). The median follow-up was 32.4 months (1.2-101.7). 1 and 2 years LC were 92.9 and 86.6%, respectively. 1 and 2 years OS were 100 and 90.6%, respectively. Multivariate analysis (MVA) associated volume of the treated lesion ≥ 13 cm3 with worse LC (p = 0.046; HR 12.1, 95%CI = 1.1-140.3). In addition, deferring SBRT > 3 months after lesion diagnosis to prioritize systemic treatment showed a significant benefit, improving the 2 years LC up to 96.8% vs. 67.5% for SBRT performed before this period (p = 0.031; HR 0.1, 95%CI = 0.01-0.8). Hormonal receptors, the total number of metastases, and CA15-3 value were significantly associated with OS in MVA. During follow-up, three non-spine fractures (5%) were observed. CONCLUSIONS: According to our data, bone SBRT is a safe and effective technique for BC. Upfront systemic treatment before SBRT offers a benefit in LC. Therefore, SBRT should be considered after prior systemic treatment in this population.

Efficacy and safety of carbon ion radiotherapy for bone sarcomas: a systematic review and meta-analysis.

OBJECTIVE: This study aimed to systematically evaluate and conduct a meta-analysis of the efficacy and safety of carbon ion radiotherapy for bone sarcomas. METHODS: We searched for articles using the PubMed, Embase, Cochrane Library, and the Web of Science databases from their inception to January 12, 2022. Two researchers independently screened the literature and extracted data based on the inclusion and exclusion criteria. Statistical analyses were performed using STATA version 14.0. RESULTS: We searched for 4378 candidate articles, of which 12 studies were included in our study according to the inclusion and exclusion criteria. Of the 897 BSs patients who received carbon ion radiotherapy in the studies, 526 patients had chordoma, 255 patients had chondrosarcoma, 112 patients had osteosarcoma, and 4 patients had other sarcomas. The local control rate at 1, 2, 3, 4, 5, and 10 years in these studies were 98.5% (95% confidence interval [CI] = 0.961-1.009, I2 = 0%), 85.8% (95% CI = 0.687-1.030, I2 = 91%), 86% (95% CI = 0.763-0.957, I2 = 85.3%), 91.1% (95% CI = 0.849-0.974), 74.3% (95% CI = 0.666-0.820, I2 = 85.2%), and 64.7% (95% CI = 0.451-0.843, I2 = 95.3%), respectively. The overall survival rate at 1, 2, 3, 4, 5, and 10 years in these studies were 99.9% (95% CI = 0.995-1.004, I2 = 0%), 89.6% (95% CI = 0.811-0.980, I2 = 96.6%), 85% (95% CI = 0.750-0.950, I2 = 89.4%), 92.4% (95% CI = 0.866-0.982), 72.7% (95% CI = 0.609-0.844, I2 = 95.3%), and 72.1% (95% CI = 0.661-0.781, I2 = 46.5%), respectively. Across all studies, the incidence of acute and late toxicities was mainly grade 1 to grade 2, and grade 1 to grade 3, respectively. CONCLUSION: As an advanced radiotherapy, carbon ion radiotherapy is promising for patients with bone sarcomas that are unresectable or residual after incomplete surgery. The data indicated that carbon ion radiotherapy was safe and effective for bone sarcomas, showing promising results for local control, overall survival, and lower acute and late toxicity. PROSPERO REGISTRATION NUMBER: CRD42021258480.

MicroRNA-802 promotes the progression of osteosarcoma through targeting p27 and activating PI3K/AKT pathway.

PURPOSE: Increasing evidences suggest dysfunctions of microRNAs (miRNAs) are playing important part in tumors. Therefore, the role of miR-802 in osteosarcoma (OS) was exploited. The object was to evaluate the effect of miR-802 and verify its influence on p27 Kip1 (p27) in OS. METHODS: RT-qPCR experiment was used to detect miR-802 and p27 expression in OS tissues and cells. We explored the function of miR-802 through Transwell assays. The phosphoinositide 3-kinase (PI3K)/AKT serine/threonine kinase pathway and epithelial-mesenchymal transition (EMT) was detected by Western blot assays. Luciferase assay was used to testify the target of miR-802. RESULTS: MiR-802 expression was elevated in OS, which was related to poor clinical outcome in OS patients. MiR-802 overexpression promoted OS migration, invasion and EMT. Further, p27 is a direct target of miR-802. P27 elevation counteracted the promotion effect of OS on EMT, migration and invasion induced by miR-802. In addition, miR-802 overexpression inactivated PI3K/AKT pathway via targeting p27 in OS. CONCLUSION: MiR-802 promoted the progress of EMT, migration and invasion in OS via targeting p27. This newly identified miR-802/p27/PI3K/AKT axis may represent potential targets for OS.

Outcomes of Osteosarcoma in Children Without High-Dose Methotrexate: Could It Be Less Toxic Without Effecting Survival Rates?

Background: Osteosarcoma (OS) is the most common primary bone sarcoma in childhood. High-dose methotrexate, doxorubicine, cisplatin, and/or ifosfamide combinations are used as standard treatment in chemotherapy and could cause serious toxicity. Another alternative chemotherapy protocol is consisting of epirubicin, ifosfamide, and cisplatin (ECI), which we use in our center. The aim of this study was to evaluate the patients with OS who were treated with ECI protocol, retrospectively. Methods: Forty-three patients with OS diagnosed at our center between December 1995 and September 2017 were evaluated retrospectively. Results: The mean follow-up period was 31 months (5-145 months). Recurrence was detected in 15 of 43 patients. When the factors affecting relapse are examined, recurrence was higher in patients who were older than 10 years at the time of diagnosis, upper extremity involvement, osteoblastic, and chondroblastic subgroups, but there was no statistically significant difference. Five-year and 10-year overall survival rates were 67.4% and 58.9%, and event-free survival rates were 54% and 47.3%, respectively. While 5-year overall survival rate was 86.7% in nonrecurrent cases, this rate was 40.9% in recurrent cases and this difference was statistically significant (p = 0.023). Just two patients died because of the toxicity. Conclusion: The prognosis of OS is still poor in relapse cases, so the choice of chemotherapy for neoadjuvant and adjuvant therapy is vital. When the risk of toxicity is also considered, the first step of ECI protocol is seen as a preferable treatment option because the survival rates are similar to the literature.

Vincristine, Irinotecan, and Temozolomide as a Salvage Regimen for Relapsed or Refractory Sarcoma in Children and Young Adults.

PURPOSE: No standard salvage regimen is available for relapsed or refractory sarcoma. We investigated the efficacy and toxicity of the vincristine, irinotecan, and temozolomide combination (VIT) for relapsed or refractory sarcomas of variable histology in children and young adults. MATERIALS AND METHODS: We retrospectively reviewed data from the relapsed or refractory sarcoma patients who were treated with VIT. The VIT protocol was given every 3 weeks as follows: vincristine, 1.5 mg/m2 intravenously on day 1, irinotecan, 50 mg/m2/day intravenously on days 1-5, and temozolomide, 100 mg/m2/day orally on days 1-5. RESULTS: A total of 26 patients (12 males) with various sarcoma histology were included in the study. Most common diagnosis was rhabdomyosarcoma (n=8) followed by osteosarcoma (n=7). Median age at the start of VIT was 18.5 years (range, 2.0 to 39.9). VIT was delivered as 2nd to 7th line of treatment, with 4th line most common (9/26, 34.6%). Median number of VIT courses given was 3 (range, 1 to 18). Of the 25 evaluable patients, there was two partial response (PR) and 11 stable disease (SD) with an overall control rate (complete remission+PR+SD) of 52%. PR was seen in one (50%) of the two evaluable patients with Ewing sarcoma and one (14.3%) of the seven patients with osteosarcoma. Overall survival and progression-free survival rates were 79.3% and 33.9% at 1 year, and 45.5% and 25.4% at 2 years, respectively. There was no treatment-related mortality. CONCLUSION: The VIT regimen was effective and relatively safe in our cohort of sarcoma patients.

CircDOCK1 promotes the tumorigenesis and cisplatin resistance of osteogenic sarcoma via the miR-339-3p/IGF1R axis.

BACKGROUND: Circular RNAs (circRNAs), a class of noncoding RNAs (ncRNAs), may modulate gene expression by binding to miRNAs. Additionally, recent studies show that circRNAs participate in some pathological processes. However, there is a large gap in the knowledge about circDOCK1 expression and its biological functions in osteogenic sarcoma (OS). METHODS: Differentially expressed circRNAs in OS cell lines and tissues were identified by circRNA microarray analysis and quantitative real-time PCR (qRT-PCR). To explore the actions of circDOCK1 in vivo and in vitro, circDOCK1 was knocked down or overexpressed. To assess the binding and regulatory associations among miR-339-3p, circDOCK1 and IGF1R, we performed rescue experiments, RNA immunoprecipitation (RIP), RNA pulldown assays and dual-luciferase assays. Moreover, we performed apoptosis assays to reveal the regulatory effects of the circDOCK1/miR-339-3p/IGF1R axis on cisplatin sensitivity. RESULTS: CircDOCK1 expression remained stable in the cytoplasm and was higher in OS tissues and cells than in the corresponding controls. Overexpression of circDOCK1 increased oncogenicity in vivo and malignant transformation in vitro. In the U2OS and MG63 cell lines, circDOCK1 modulated tumor progression by regulating IGF1R through sponging of miR-339-3p. Additionally, in the U2OS/DDP and MG63/DDP cell lines, cisplatin sensitivity was regulated by circDOCK1 via the miR-339-3p/IGF1R axis. CONCLUSIONS: CircDOCK1 can promote progression and regulate cisplatin sensitivity in OS via the miR-339-3p/IGF1R axis. Thus, the circDOCK1/miR-339-3p/IGF1R axis may be a key mechanism and therapeutic target in OS.

Osteosarcoma Patient-derived Orthotopic Xenograft (PDOX) Models Used to Identify Novel and Effective Therapeutics: A Review.

BACKGROUND/AIM: Recurrent osteosarcoma is recalcitrant with poor response rates to first-line chemotherapy due to heterogeneity and metastatic potential. This disease requires novel drug discovery and precision treatment. MATERIALS AND METHODS: The osteosarcoma patient-derived orthotopic xenograft (PDOX) mouse model mimics the clinical disease and has identified effective clinically-approved drugs and experimental agents, especially drug combinations, that hold much clinical promise. RESULTS: Effective treatment for drug-resistant osteosarcoma includes regorafenib, as monotherapy, and temozolomide-irinotecan, trabectedin-irinotecan, sorafenib-everolimus, sorafenib-palbociclib, and olaratumab-doxorubicin-cisplatinum, as combinations. CONCLUSION: The PDOX model can be used to improve the outcome of osteosarcoma patients, including individualized, precision therapy.

Osteochondroma Pathogenesis: Mouse Models and Mechanistic Insights into Interactions with Retinoid Signaling.

Osteochondromas are cartilage-capped tumors that arise near growing physes and are the most common benign bone tumor in children. Osteochondromas can lead to skeletal deformity, pain, loss of motion, and neurovascular compression. Currently, surgery is the only available treatment for symptomatic osteochondromas. Osteochondroma mouse models have been developed to understand the pathology and the origin of osteochondromas and develop therapeutic drugs. Several cartilage regulatory pathways have been implicated in the development of osteochondromas, such as bone morphogenetic protein, hedgehog, and WNT/ß-catenin signaling. Retinoic acid receptor-γ is an important regulator of endochondral bone formation. Selective agonists for retinoic acid receptor-γ, such as palovarotene, have been investigated as drugs for inhibition of ectopic endochondral ossification, including osteochondromas. This review discusses the signaling pathways involved in osteochondroma pathogenesis and their possible interactions with the retinoid pathway.

FAT10 stimulates the development of osteosarcoma by regulating the JAK/STAT signaling pathway.

PURPOSE: To investigate the potential function of FAT10 in the development of osteosarcoma (OS) and its mechanism. METHODS: Relative level of FAT10 in OS specimens and cell lines was detected by qRT-PCR. The correlation between FAT10 level and clinical features of OS patients was assessed by χ2 test. After intervention of FAT10 in MG-63 and U2OS cells, changes of FAT10 level, cell viability, clonality and proliferative capacity were respectively detected by qRT-PCR, CCK-8, colony formation and EdU assay. Moreover, dynamic change of FAT10 in OS cells induced with pro-inflammatory factors was examined by qRT-PCR. Protein levels of FAT10, p-STAT1, p-STAT3 and p-STAT5 in OS cells induced with TNF-α were determined by Western blot. The JAK2 inhibitor AZ960 was used to further confirm the role of the JAK signaling in FAT10-regulated development of OS. RESULTS: FAT10 was upregulated in OS specimens and cell lines, which was correlated to tumor size, WHO grade and distant metastasis of OS patients. Knockdown of FAT10 inhibited viability, clonality and proliferative capacity of MG-63 and U2OS cells. FAT10 was time-dependently upregulated in OS cells stimulated with IFN-γ and TNF-α, which was dose-dependently downregulated by the treatment of AZ960. Protein levels of FAT10, p-STAT1, p-STAT3 and p-STAT5 in OS cells induced with AZ960 were remarkably downregulated. CONCLUSION: FAT10 is upregulated in OS samples, which stimulates the development of OS by activating the JAK/STAT signaling pathway.

Dedifferentiated chondrosarcoma: current standards of care.

Dedifferentiated chondrosarcomas are aggressive variants of chondrosarcoma, associated with poor outcomes. Tumor biphasism is the norm. The majority of these tumors are symptomatic at presentation. Radiologically, large soft tissue masses with bony destruction predominate. Treatment protocols of these tumors are not well defined. Surgical resection forms the standard of care for localized disease. (Neo)adjuvant therapies remain controversial as the results from multiple (mainly retrospective) studies remain conflicting. Age at presentation, stage and ability to obtain negative resection margins are important prognostic factors. The overall prognosis is dismal. Newer and novel therapies targeting the complex genetic makeup of these tumors have renewed interest in the adjuvant setting that could hold promise in the near future.

Lay abstract Dedifferentiated chondrosarcomas are rare cancers composed of two components: a high-grade component and a low-grade component, with one abruptly blending into another. These rare tumors affect middle-aged individuals and present with pain and swelling in the affected site. X-rays and other scans often show tumor within the soft tissue with bony destruction. Although the precise treatment protocol is not well defined, surgery remains the standard of care for those where the tumor has not spread elsewhere. Once the disease spreads to other parts of the body, the outcome is very poor. The role of certain drugs targeting the tumor (chemotherapeutic agents) is controversial. This review briefly describes the genetic basis, treatment modalities involved and newer agents being developed for this lethal cancer.

SHP-2 deletion in CD4Cre expressing chondrocyte precursors leads to tumor development with wrist tropism.

Due to redundancy with other tyrosine phosphatases, the ubiquitously expressed tyrosine phosphatase SHP-2 (encoded by Ptpn11) is not required for T cell development. However, Ptpn11 gene deletion driven by CD4 Cre recombinase leads to cartilage tumors in the wrist. Using a fate mapping system, we demonstrate that wrist tumor development correlates with increased frequency and numbers of non-hematopoietic lineage negative CD45 negative cells with a bone chondrocyte stromal cell precursor cell (BCSP) phenotype. Importantly, the BCSP subset has a history of CD4 expression and a marked wrist location tropism, explaining why the wrist is the main site of tumor development. Mechanistically, we found that in SHP-2 absence, SOX-9 is no longer regulated, leading to an uncontrolled proliferation of the BCSP subset. Altogether, these results identify a unique subset of chondrocyte precursors tightly regulated by SHP-2. These findings underscore the need for the development of methods to therapeutically target this subset of cells, which could potentially have an impact on treatment of SHP-2 dysfunction linked debilitating diseases.

hsa_circ_0005721 triggers proliferation, migration and invasion of osteosarcoma by upregulating the linear transcript TEP1.

PURPOSE: This study aimed to illustrate the biological role of hsa_circ_0005721 in the development of osteosarcoma and the molecular mechanism. METHODS: hsa_circ_0005721 levels in 30 pairs of osteosarcoma and non-tumor tissues were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Functional experiments were conducted to assess the influence of hsa_circ_0005721 on proliferative, metastatic and apoptotic rates of osteosarcoma cells. The downstream target of hsa_circ_0005721 and their co-regulatory mechanism in malignant development of osteosarcoma were analyzed by dual-luciferase reporter assay and rescue experiments, respectively. RESULTS: hsa_circ_0005721 was upregulated in osteosarcoma tissues and cell lines. Knockdown of hsa_circ_0005721 suppressed proliferative and metastatic rates of U-2OS and Saos-2 cells, and stimulated apoptosis. Serving as a ceRNA, hsa_circ_0005721 upregulated the linear transcript TEP1 by competitively binding miR-16-5p, thus exerting its biological functions in regulating osteosarcoma development. CONCLUSIONS: This study for the first time identified the upregulated hsa_circ_0005721 in osteosarcoma, which triggers the malignant development of osteosarcoma by upregulating the linear transcript TEP1.

Analysis of the signal cross talk via CCL26 in the tumor microenvironment in osteosarcoma.

Interaction with surrounding healthy cells plays a major role in the growth and metastasis of osteosarcoma. In this study, we hypothesized that humoral factors, which do not require direct contact with cells, are involved in the interaction between osteosarcoma and the surrounding cells. We identified the humoral factor involved in the association between tumor cells and surrounding normal cells using a co-culture model and investigated the significance of our findings. When human osteosarcoma cells (MG63) and human mesenchymal stem cells (hMSCs) were co-cultured and comprehensively analyzed for changes in each culture group, we found that the expression of chemokine (CC motif) ligand 26 (CCL26) was significantly enhanced. We also analyzed the changes in cell proliferation in co-culture, enhanced interaction with administration of recombinant CCL26 (rCCL26), reduced interaction with administration of anti-CCL26 antibodies, changes in invasive and metastatic abilities. CCL26 levels, motility, and invasive capability increased in the co-culture group and the group with added rCCL26, compared to the corresponding values in the MG63 single culture group. In the group with added CCL26 neutralizing antibodies, CCL26 level decreased in both the single and co-culture groups, and motility and invasive ability were also reduced. In a nude mice lung metastasis model, the number of lung metastases increased in the co-culture group and the group with added rCCL26, whereas the number of tumors were suppressed in the group with added neutralizing antibodies compared to those in the MG63 alone. This study identified a possible mechanism by which osteosarcoma cells altered the properties of normal cells to favorably change the microenvironment proximal to tumors and to promote distant metastasis.

A single-center experience with giant cell tumors of sphenoid bone and clivus.

OBJECTIVE: To present pathologic, clinical, and treatment findings for giant cell tumors (GCTs) of sphenoid bone and clivus. METHODS: We describe the optimal treatment algorithm in patients with a histopathologic diagnosis of bone GCT by presenting the effects of denosumab treatment in both pediatric and adult patients with GCT undergoing endoscopic transnasal surgery. Clinicopathologic correlation is crucial for the differential diagnosis of GCT and the choice of treatment modality. CONCLUSION: GCT of bone is a local aggressive tumor that accounts for about 3%-7% of all bone tumors. GCTs located in the cranium are extremely uncommon neoplasms. There are no defined guidelines for the treatment of GCTs in skull base. Following surgical resection of the tumor, the addition of denosumab treatments to radiotherapy has a significant role in preventing the recurrence of GCT and in promoting regression of residual tumor size.

Telangiectatic osteosarcoma arising in osteogenesis imperfecta.

We present the case of a 32-year-old man with a diagnosis of type-III osteogenesis imperfecta who developed a telangiectatic osteosarcoma in the proximal right tibia. An above-knee amputation was performed and after one-year follow-up, pulmonary metastatic lesions were detected on the thoracic CT scan. Palliative chemotherapy was proposed and to date the patient is still living and is under medical treatment. The association between osteogenesis imperfecta and osteosarcoma is rare. There are only ten confirmed reports of this unusual situation, but to our knowledge this is the first case reported with a telangiectatic osteosarcoma arising in this particular setting.

Metabolism in the Tumour-Bone Microenvironment.

PURPOSE OF REVIEW: For solid tumours such as breast and prostate cancer, and haematological malignancies such as myeloma, bone represents a supportive home, where the cellular crosstalk is known to underlie both tumour growth and survival, and the development of the associated bone disease. The importance of metabolic reprogramming is becoming increasingly recognised, particularly within cancer biology, enabling tumours to adapt to changing environments and pressures. This review will discuss our current understanding of metabolic requirements and adaptations within the tumour-bone microenvironment. RECENT FINDINGS: The bone provides a unique metabolic microenvironment, home to highly energy-intensive processes such as bone resorption and bone formation, both of which are dysregulated in the presence of cancer. Approaches such as metabolomics demonstrate metabolic plasticity in patients with advanced disease. Metabolic crosstalk between tumour cells and surrounding stroma supports disease pathogenesis. There is increasing evidence for a key role for metabolic reprogramming within the tumour-bone microenvironment to drive disease progression. As such, understanding these metabolic adaptations should reveal new therapeutic targets and approaches.

The Role of Inflammation in Breast and Prostate Cancer Metastasis to Bone.

Tumor metastasis to bone is a common event in multiple forms of malignancy. Inflammation holds essential functions in homeostasis as a defense mechanism against infections and is a strategy to repair injured tissue and to adapt to stress conditions. However, exaggerated and/or persistent (chronic) inflammation may eventually become maladaptive and evoke diseases such as autoimmunity, diabetes, inflammatory tissue damage, fibrosis, and cancer. In fact, inflammation is now considered a hallmark of malignancy with prognostic relevance. Emerging studies have revealed a central involvement of inflammation in several steps of the metastatic cascade of bone-homing tumor cells through supporting their survival, migration, invasion, and growth. The mechanisms by which inflammation favors these steps involve activation of epithelial-to-mesenchymal transition (EMT), chemokine-mediated homing of tumor cells, local activation of osteoclastogenesis, and a positive feedback amplification of the protumorigenic inflammation loop between tumor and resident cells. In this review, we summarize established and evolving concepts of inflammation-driven tumorigenesis, with a special focus on bone metastasis.

Assessment of the viability and treatment response of bone metastases in patients with metastatic castration-resistant prostate cancer using choline PET/CT.

ABSTRACT: This study aimed to evaluate the clinical use of choline-PET/CT for discriminating viable progressive osteoblastic bone metastasis from benign osteoblastic change induced by the treatment effect and evaluating the response of bone metastasis to treatment in metastatic castration-resistant prostate cancer (mCRPC) patients. Thirty patients with mCRPC underwent a total of 56 11C-choline-PET/CT scans for restaging, because 4 patients received 1 scan and 26 had 2 scans. Using 2 (pre- and post-treatment) 11C-choline-PET/CT examinations per patient, treatment response was assessed according to European Organization for Research and Treatment of Cancer (EORTC) criteria in 20 situations, in which only bony metastases were observed on 11C-choline-PET/CT scans. Viable bone metastases and osteoblastic change induced by the treatment effect were identified in 53 (94.6%) and 29 (51.8%) of 56 11C-choline-PET/CT scans, respectively. In 27 cases (48.2%), 11C-choline-PET/CT scans could discriminate the 2 entities. The mean SUVmax of the metastatic bony lesions was 5.82 ±â€Š3.21, 5.95 ±â€Š3.96, 6.73 ±â€Š5.04, and 7.91 ±â€Š3.25 for the osteoblastic, osteolytic, mixed, and invisible types, respectively. Of the 20 situations analyzed, CMR, PMR, SMD, and PMD, as determined by the EORTC, were seen in 1, 2, 3, and 14 cases, respectively. Of the 13 patients with increasing PSA trend, all 13 showed PMD. Of the 2 patients with PSA response of <50%, both 2 showed SMD. Of the 5 patients with PSA response of ≥50%, 1 showed CMR, 2 showed PMR, 1 showed SMD, and 1 showed PMD. Choline-PET/CT is very useful to discriminate viable progressive osteoblastic bone metastasis from osteoblastic change, and assess treatment response of bone metastases in mCRPC.