Management of bone metastases in cancer: a review

Sites of Synchronous Distant Metastases, Prognosis, and Nomogram for Small Cell Lung Cancer Patients with Bone Metastasis: A Large Cohort Retrospective Study

Background

Small cell lung cancer (SCLC) is often associated with metastases at the time of diagnosis, and the bone is one of the most common sites. The primary aim of this study was to investigate the site of synchronous distant metastasis to other organs in SCLC patients with bone metastasis (BM) and develop a robust predictive prognostic model.

Methods

We retrospectively analyzed the data from patients diagnosed with SCLC with BM in the Surveillance, Epidemiology, and End Results database. Univariate and multivariate Cox analyses were used to identify independent prognostic factors. A prognostic nomogram was constructed and evaluated by calibration curves, receiver operating characteristic (ROC) curves, and decision curve analysis (DCA). Then, according to the sites of metastasis and treatment modality, all patients were stratified into several subgroups. The relationship among sites of metastasis, treatment modality, and overall survival was then analyzed.

Results

A total of 6253 patients were included. Independent prognostic factors for SCLC with BM were age, sex, primary site, radiotherapy, chemotherapy, brain metastasis, liver metastasis, and marital status. Calibration, ROC curves, and DCA indicated the excellent performance of the prognostic nomogram. The liver is the most common organ for extraskeletal metastases, followed by the lung. Patients with only BM had the longest mean survival time (9.30 ± 0.31 months). In the subgroup analysis, chemotherapy was an independent prognostic factor for all subgroups. In contrast, radiotherapy showed a positive effect on the prognosis of patients in all subgroups except those with bone and brain metastases and those with bone, lung, and brain metastases.

Conclusions

The prognostic nomogram is expected to be an accurate and personalized tool for predicting the prognosis of SCLC patients with BM. Additionally, the determination of the sites of synchronous extraskeletal metastases and the associated prognosis helps in treatment selection.

Modeling bystander effects that cause growth delay of breast cancer xenografts in bone marrow of mice treated with radium-223

RATIONALE

The role of radiation-induced bystander effects in cancer therapy with alpha-particle emitting radiopharmaceuticals remains unclear. With renewed interest in using alpha-particle emitters to sterilize disseminated tumor cells, micrometastases, and tumors, a better understanding of the direct effects of alpha particles and the contribution of the bystander responses they induce is needed to refine dosimetric models that help predict clinical benefit. Accordingly, this work models and quantifies the relative importance of direct effects (DE) and bystander effects (BE) in the growth delay of human breast cancer xenografts observed previously in the tibiae of mice treated with 223RaCl2.

METHODS

A computational model of MDA-MB-231 and MCF-7 human breast cancer xenografts in the tibial bone marrow of mice administered 223RaCl2 was created. A Monte Carlo radiation transport simulation was performed to assess individual cell absorbed doses. The responses of the breast cancer cells to direct alpha particle irradiation and gamma irradiation were needed as input data for the model and were determined experimentally using a colony-forming assay and compared to the responses of preosteoblast MC3T3-E1 and osteocyte-like MLO-Y4 bone cells. Using these data, a scheme was devised to simulate the dynamic proliferation of the tumors in vivo, including DE and BE propagated from the irradiated cells. The parameters of the scheme were estimated semi-empirically to fit experimental tumor growth.

RESULTS

A robust BE component, in addition to a much smaller DE component, was required to simulate the in vivo tumor proliferation. We also found that the relative biological effectiveness (RBE) for cell killing by alpha particle radiation was greater for the bone cells than the tumor cells.

CONCLUSION

This modeling study demonstrates that DE of radiation alone cannot explain experimental observations of 223RaCl2-induced growth delay of human breast cancer xenografts. Furthermore, while the mechanisms underlying BE remain unclear, the addition of a BE component to the model is necessary to provide an accurate prediction of the growth delay. More complex models are needed to further comprehend the extent and complexity of 223RaCl2-induced BE.

A Murine Bone Metastasis Model Using Caudal Artery Injection and Bioluminescence Imaging

The current standard murine model of bone metastasis by using intracardiac injection (IC) has some limitations despite the great utility of this model. This fact emphasizes the need for a new murine model to accelerate basic research of bone metastasis. The present protocol provides instructions on caudal artery (CA) injection that is an easy-to-use method to reliably construct a murine bone metastasis model with a variety type of cancer cell lines. Bioluminescence imaging visualized that cancer cells injected via the caudal artery in the tail were efficiently delivered to a hind limb bone, where it is a common site affected with bone metastasis in mice. CA injection rarely causes stress-induced acute death in mice and enables us to inject a large number of cancer cells, thereby greatly increasing the frequency of bone metastasis in hind limb bones. Importantly, CA injection is technically as easy as tail vein injection and causes no lethal stress, indicating that it is a model that also contributes to animal welfare. CA injection model, therefore, could represent a powerful tool for many researchers to study molecular mechanisms of bone metastasis in mice.

"The use of bisphosphonates to treat skeletal complications in solid tumours"

The skeleton is the most common site of secondary disease in breast cancer and prostate cancer, with up to 80% of patients with advanced disease developing bone metastases (BM). The proportion is also substantial in advanced lung cancer (20%-40%). Because of the high prevalence of cancers of the breast, prostate and lung, these cancers account for more than 80% of cases of metastatic bone disease occurring in solid tumours. Metastatic bone disease is associated with greatly increased bone resorption by osteoclasts, leading to moderate to severe pain and other skeletal complications, with major impact on quality of life (QoL). Skeletal Related Events (SREs) have been defined as: pathological long bone or vertebral fractures; spinal cord compression; need for radiation for pain relief or to prevent fracture/spinal cord compression, need for surgery to bone and hypercalcaemia. More recently, Symptomatic Skeletal Events (SSEs) have been defined to monitor QoL. Although there are currently no curative treatments for metastatic bone disease, patients with breast or prostate cancer and BM are now surviving for several years and sometimes longer, and prevention of SREs is the key aim to optimization of QoL. Since their discovery 50 years ago and their introduction more than 30 years ago into the field of metastatic bone disease, a range of oral and intravenous bisphosphonate drugs have made a major contribution to prevention of SREs. Large trials have clearly demonstrated the clinical value of different bisphosphonate-based drugs (including the oral drugs ibandronate and clodronate and intravenous agents such as zoledronate and pamidronate), in treatment of hypercalcaemia of malignancy and the reduction of SREs and SSEs in a range of cancers. Despite the success of denosumab in reducing osteolysis, bisphosphonates also remain mainstay drugs for treatment of metastatic bone disease. Recognizing the 50th Anniversary of the discovery of bisphosphonates, this review focuses on their continuing value in BM treatment and their future potential, for example in providing a bone-targeting vehicle for cytotoxic drugs.

PNMA5 Promotes Bone Metastasis of Non-small-Cell Lung Cancer as a Target of BMP2 Signaling

Bone metastases frequently occur in NSCLC patients at the late stage, indicating poor survival. However, mechanisms about the initiation of NSCLC bone metastases remain largely unclear. In our previous reports, BMP2 signaling activation has been found to enhance NSCLC bone metastases through enhancing carcinoma cells migration, invasion, osteoclasts differentiation and osteoblasts immature differentiation. Nevertheless, downstream target genes of BMP2 contributing to those processes still remain unknown. In this project, we find that the expression of Pnma5 is higher in metastatic bone tumors of Lewis lung carcinoma than in metastatic lung tumors and parental Lewis lung cells. Pnma5 overexpression not only can promote cell migration and invasion of NSCLC cells but also tumor-induced osteoclasts differentiation. Interestingly, knockdown of Pnma5 in Lewis lung cells blocks BMP2 signaling from inducing Lewis lung cells migration and invasion. Although BMP2 signaling can promote Lewis lung cells-induced osteoclasts differentiation from macrophages, this effect can also be blocked when Pnma5 is knocked down in Lewis lung cells. Moreover, Pnma5 can promote NSCLC bone metastases in vivo as the downstream target of BMP2. Those results above indicate that BMP2 signaling enhances NSCLC bone metastases via its direct downstream target gene Pnma5. This research reveals the detailed molecular mechanism about how BMP2 signaling contributes to NSCLC bone metastases via PNMA5 and provides a new potential therapeutic target for the treatment of NSCLC bone metastases.

Extracellular Matrix Components Regulate Bone Sialoprotein Expression in MDA-MB-231 Breast Cancer Cells

Bone sialoprotein (BSP) has become a target in breast cancer research as it is associated with tumor progression and metastasis. The mechanisms underlying the regulation of BSP expression have been largely elusive. Given that BSP is involved in the homing of cancer cells in bone metastatic niches, we addressed regulatory effects of proteolytic cleavage and extracellular matrix components on BSP expression and distribution in cell culture models. Therefore, MDA-MB-231 human breast cancer cells were kept in 2D and 3D spheroid cultures and exposed to basement membrane extract in the presence or absence of matrix metalloproteinase 9 or the non-polar protease, dispase. Confocal imaging of immunofluorescence samples stained with different antibodies against human BSP demonstrated a strong inducing effect of basement membrane extract on anti-BSP immunofluorescence. Similarly, protease incubation led to acute upregulation of anti-BSP immunofluorescence signals, which was blocked by cycloheximide, suggesting de novo formation of BSP. In summary, our data show that extracellular matrix components play an important function in regulating BSP expression and hint at mechanisms for the formation of bone-associated metastasis in breast cancer that might involve local control of BSP levels by extracellular matrix degradation and release of growth factors.

Progress in Targeted Alpha-Particle-Emitting Radiopharmaceuticals as Treatments for Prostate Cancer Patients with Bone Metastases

Bone metastasis remains a major cause of death in cancer patients, and current therapies for bone metastatic disease are mainly palliative. Bone metastases arise after cancer cells have colonized the bone and co-opted the normal bone remodeling process. In addition to bone-targeted therapies (e.g., bisphosphonate and denosumab), hormone therapy, chemotherapy, external beam radiation therapy, and surgical intervention, attempts have been made to use systemic radiotherapy as a means of delivering cytocidal radiation to every bone metastatic lesion. Initially, several bone-seeking beta-minus-particle-emitting radiopharmaceuticals were incorporated into the treatment for bone metastases, but they failed to extend the overall survival in patients. However, recent clinical trials indicate that radium-223 dichloride (223RaCl2), an alpha-particle-emitting radiopharmaceutical, improves the overall survival of prostate cancer patients with bone metastases. This success has renewed interest in targeted alpha-particle therapy development for visceral and bone metastasis. This review will discuss (i) the biology of bone metastasis, especially focusing on the vicious cycle of bone metastasis, (ii) how bone remodeling has been exploited to administer systemic radiotherapies, and (iii) targeted radiotherapy development and progress in the development of targeted alpha-particle therapy for the treatment of prostate cancer bone metastasis.

Can a Novel Scoring System Improve on the Mirels Score in Predicting the Fracture Risk in Patients with Multiple Myeloma?

BACKGROUND

Stratification of the fracture risk is an important treatment component for patients with multiple myeloma, which is associated with up to an 80% risk of pathologic fracture. The Mirels score, which is commonly used to estimate the fracture risk for patients with osseous lesions, was evaluated in a cohort in which fewer than 15% of lesions were caused by multiple myeloma. The behavior of multiple myeloma lesions often differs from that of lesions caused by metastatic disease, and accurate risk stratification is critical for effective care. To our knowledge, the Mirels score has not been validated specifically for multiple myeloma.

QUESTIONS/PURPOSES

Our purpose was: (1) To develop a novel scoring system for the prediction of pathologic fracture in patients with long-bone lesions from multiple myeloma; and (2) to compare the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and receiver operating characteristic (ROC) area under curve (AUC) between the novel scoring system and the Mirels system.

METHODS

Between 2003 and 2017, 763 patients at one center with the diagnosis of multiple myeloma were reviewed, of whom 174 presented with long-bone disease involvement. Of those, 5% (nine of 174) were missing data or radiographs at a minimum of 1 year and had not reached an endpoint (fracture or surgery) before that time and were therefore excluded. Many patients have more than one lesion; consequently, we used the largest lesion in each patient, resulting in 163 lesions in as many patients. Ten percent (16 of 163) of these patients eventually developed a fracture and 4% (six of 163) underwent prophylactic stabilization (excluded from analysis because of outcome uncertainty). During the study period, prophylactic stabilization was performed at the discretion of the orthopaedic oncologist. Fifty-one percent (83 of 163) of patients were female, and the mean (± SD) age was 60 ± 10 years at radiographic lesion identification. All lesions were characterized before determining whether the patient underwent pathologic fracture. We identified variables associated with pathologic fracture on univariate analysis. Variables independently significant on logistic regression analysis were used to generate scoring algorithms at varying weights and scoring cutoffs for comparison via ROC curves. We then selected a novel score based on ROC performance, and compared the sensitivity, specificity, PPV, and NPV of that scoring system to that of Mirels score. ROC AUCs were compared after bootstrapping 100,000 iterations. Alpha was set at 0.05.

RESULTS

After controlling for potential confounders, such as age, sex, and duration of myeloma diagnosis, we found the following factors were independently associated with the occurrence of pathologic fracture: larger lesion size (area, cm2) (log odds 0.17; p = 0.03), longer lesion latency (years from diagnosis to lesion identification) (log odds 0.25; p = 0.03), presence of pain (relative risk [RR] 2.9; p = 0.04), and metaphyseal location (RR 3.2, compared with epiphyseal or diaphyseal; p = 0.003). These variables were used to formulate a novel scoring system. Compared with the Mirels system, the novel system was more sensitive (69% [95% CI 61 to 76] versus 38% [95% CI 30 to 46]; p < 0.05) but not different in terms of specificity (87% [95% CI 80 to 91] versus 87% [95% CI 81 to 92]; p > 0.05), PPV (37% [95% CI 29 to 45] versus 25% [95% CI 19 to 33]; p > 0.05), NPV (96% [95% CI 91 to 99] versus 92% [95% CI 87 to 96]; p > 0.05), or AUC (0.85 [95% CI 0.74 to 0.92] versus 0.67 [95% CI 0.51 to 0.81]; p > 0.05).

CONCLUSION

The novel scoring system was found to be more sensitive than the Mirels system for predicting pathologic fracture in our retrospective cohort of patients with multiple myeloma-related bone disease. Specificity, PPV, NPV, and ROC AUC were not different with the numbers available. Thus, the novel scoring system may serve as a more effective screening tool to determine which patients with multiple myeloma would benefit from further radiologic or orthopaedic evaluation based on a skeletal survey.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Clinicopathologic characteristics, metastasis-free survival, and skeletal-related events in 628 patients with skeletal metastases in a tertiary orthopedic and trauma center

Background

Skeletal-related events (SREs) due to bone metastases (BM) significantly impact the morbidity and mortality of cancer patients. The present study sought to investigate clinicopathological characteristics, metastasis-free survival (MFS), and SREs in patients referred to a tertiary orthopedic and trauma center.

Methods

Data were retrieved from electronic health records (n=628). Survival curves were estimated utilizing the Kaplan–Meier method. The Cox regression model was used to determine factors influencing MFS based on estimated hazard ratios (HRs).

Results

Breast (55.8%) and lung (18.2%), and lung (32.9%) and prostate (16.8%) cancer were the most common cancer types in our cohort in women and men, respectively. Fifteen percent of patients presented with BM as the first manifestation of tumor disease, 23% had metastasis diagnosis on the same day of primary tumor diagnosis or within 3 months, and 62% developed BM at least 3 months after primary tumor diagnosis. Osteolytic BM were predominant (72.3%) and most commonly affecting the spine (23%). Overall median MFS was 45 months (32 (men) vs. 53 (women) months). MFS was shortest in the lung (median 15 months, 95% CI 8.05–19) and longest in breast cancer (median 82 months, 95% CI 65.29–94). Age (≥ 60 vs. < 60 years) and primary cancer grading of ≥2 vs. 1 revealed prognostic relevance.

Conclusion

Women with breast or lung cancer, men with lung or prostate cancer, age ≥60 years, male sex, and primary cancer grading ≥2 are associated with increased risk for MBD. Intensified follow-up programs may reduce the risk of SREs and associated morbidity and mortality.

Features of Spinal Metastases: A Retrospective View

BACKROUND

The present study aimed to determine the frequency of spinal metastases, to evaluate the features of spinal metastases, and to reveal clues to shed light on the origin of spinal metastases with unknown primary.

METHODS

The data of patients who were followed up with the diagnosis of cancer in Istanbul Oncology Hospital between 2017 and 2019 were analyzed retrospectively. A total of 156 patients with spinal metastases and without visceral metastases were included in the study by applying inclusion and exclusion criteria. Clinical data, pathological diagnostic reports, and positron emission tomography-computed tomography results of 156 patients were evaluated. The groups were evaluated in terms of age, gender, number of spinal metastases (single focus, multiple focus), and localization of spinal metastasis. The spinal localization evaluation included both the main anatomical localizations and a detailed evaluation of each spine.

RESULTS

The most common metastasis region was the thoracic spine in respiratory system cancers (28.38%), the thoracic + lumbar spine in breast (42.42%), prostate (50.00%), and gynecologic (40.00%) cancers, and the lumbar spine in gastrointestinal (37.50%) and urinary (30.00%) tract cancers (P = .313). C5 spinal metastasis percentages were significantly higher in breast and gastrointestinal tract cancers than the others (P = .042). T5 spinal metastasis percentage was significantly higher in gynecologic tumors than in the other cancers (P = .002). T10 spinal metastasis percentages were significantly higher in prostate and gynecologic tumors than the others (P = .016). L1 spinal metastasis percentage was significantly higher in breast tumors (P = .009). L2 spinal metastasis percentages were significantly higher in breast, prostate, and gynecologic tumors (P = .011). L4 spinal metastasis percentages were significantly higher in breast and prostate tumors (P = .041). L5 spinal metastasis percentage was significantly higher in prostate tumors (P = .029) than the other cancers.

CONCLUSIONS

It was observed that primary cancers were often prone to metastasis to nearby spine. The results obtained by detailed examination of spinal metastases may provide a clinical benefit by providing clues in investigation of primary unknown cancers.

LEVEL OF EVIDENCE

3.

Better pain control with 8-gray single fraction palliative radiotherapy for skeletal metastases: a Bayesian network meta-analysis

External Beam Radiotherapy (EBRT) allows remarkable pain control in patients with skeletal metastases. We performed a Bayesian network meta-analysis comparing the most commonly used radiotherapy regimens for palliative management in patients with skeletal metastases. The main online databases were accessed in October 2020. All randomized clinical trials evaluating the irradiation of painful bone metastases were considered. The following irradiation patterns were analysed and included in the present network meta-analysis: 8 Gy- and 10 Gy/single fraction, 20 Gy/5 fractions, 30 Gy/10 fractions. The Bayesian hierarchical random-effect model analysis was adopted in all comparisons. The Log Odds-Ratio (LOR) statistical method for dichotomic data was adopted for analysis. Data from 3595 patients were analysed. The mean follow-up was 9.5 (1 to 28) months. The cumulative mean age was 63.3 ± 2.9. 40.61% (1461 of 3595 patients) were female. The 8Gy/single fraction protocol detected reduced rate of “no pain response” (LOR 3.39), greater rate of “pain response” (LOR-5.88) and complete pain remission (LOR-7.05) compared to the other dose patterns. The 8Gy group detected a lower rate of pathological fractures (LOR 1.16), spinal cord compression (LOR 1.31) and re-irradiation (LOR 2.97) compared to the other dose patterns. Palliative 8Gy/single fraction radiotherapy for skeletal metastases shows outstanding results in terms of pain control, re-irradiations, pathological fractures and spinal cord compression, with no differences in terms of survivorship compared to the other multiple dose patterns.

Level of evidence: I, Bayesian network meta-analysis of RCTs.

Characteristics and Predictors of Radiographic Local Failure in Patients With Spinal Metastases Treated With Palliative Conventional Radiation Therapy

Purpose

Although local control is an important issue for longer-term survivors of spinal metastases treated with conventional external beam radiation therapy (EBRT), the literature on radiographic local failure (LF) in these patients is sparse. To inform clinical decision-making, we evaluated rates, consequences, and predictors of radiographic LF in patients with spinal metastases managed with palliative conventional EBRT alone.

Methods and Materials

We retrospectively reviewed 296 patients with spinal metastases who received palliative EBRT at a single institution (2006-2013). Radiographic LF was defined as radiologic progression within the treatment field, with death considered a competing risk. Kaplan-Meier, cumulative incidence, and Cox regression analyses determined overall survival estimates, LF rates, and predictors of LF, respectively.

Results

There were 182 patients with follow-up computed tomography or magnetic resonance imaging; median overall survival for these patients was 7.7 months. Patients received a median of 30 Gy in 10 fractions to a median of 4 vertebral bodies. Overall, 74 of 182 patients (40.7%) experienced LF. The 6-, 12-, and 18-month LF rates were 26.5%, 33.1%, and 36.5%, respectively, while corresponding rates of death were 24.3%, 38.1%, and 45.9%. Median time to LF was 3.8 months. Of those with LF, 51.4% had new compression fractures, 39.2% were admitted for pain control, and 35.1% received reirradiation; median time from radiation therapy (RT) to each of these events was 3.0, 5.7, and 9.2 months, respectively. Independent predictors of LF included single-fraction RT (8 Gy) (hazard ratio [HR], 2.592; 95% confidence interval [CI], 1.437-4.675; P = .002), lung histology (HR, 3.568; 95% CI, 1.532-8.309; P = .003), and kidney histology (HR, 4.937; 95% CI, 1.529-15.935; P = .008).

Conclusions

Patients experienced a >30% rate of radiographic LF by 1 year after EBRT. Single-fraction RT and lung or kidney histology predicted LF. Given the high rates of LF for patients with favorable prognosis, assessing the risk of death versus LF is important for clinical decision-making.

Targeting cancer metastasis with antibody therapeutics

Cancer metastasis, the spread of disease from a primary to a distal site through the circulatory or lymphatic systems, accounts for over 90% of all cancer related deaths. Despite significant progress in the field of cancer therapy in recent years, mortality rates remain dramatically higher for patients with metastatic disease versus those with local or regional disease. Although there is clearly an urgent need to develop drugs that inhibit cancer spread, the overwhelming majority of anticancer therapies that have been developed to date are designed to inhibit tumor growth but fail to address the key stages of the metastatic process: invasion, intravasation, circulation, extravasation, and colonization. There is growing interest in engineering targeted therapeutics, such as antibody drugs, that inhibit various steps in the metastatic cascade. We present an overview of antibody therapeutic approaches, both in the pipeline and in the clinic, that disrupt the essential mechanisms that underlie cancer metastasis. These therapies include classes of antibodies that indirectly target metastasis, including anti-integrin, anticadherin, and immune checkpoint blocking antibodies, as well as monoclonal and bispecific antibodies that are specifically designed to interrupt disease dissemination. Although few antimetastatic antibodies have achieved clinical success to date, there are many promising candidates in various stages of development, and novel targets and approaches are constantly emerging. Collectively, these efforts will enrich our understanding of the molecular drivers of metastasis, and the new strategies that arise promise to have a profound impact on the future of cancer therapeutic development. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Prognosis of medication-related osteonecrosis of the jaws in cancer patients using antiresorptive agent zoledronic acid

BACKGROUND/PURPOSE

Anti-resorptive agents are commonly used in cancer patients with bone metastasis or multiple myeloma (MM). An adverse event termed medication-related osteonecrosis of the jaws (MRONJ) was discovered in patients using these agents but relatively little attention has been paid to its prognosis. Our aims were to find out the treatment outcomes and prognostic indicators of MRONJ in cancer patients who received zoledronic acid as antiresorptive therapy.

METHODS

We retrospectively surveyed a cohort of 133 cancer patients who received zoledronic acid. A total of 150 MRONJ lesions were included for investigation. Cumulative complete response rate after treatment was calculated with the Kaplan-Meier method, and significance was examined with the log-rank tests. Cox regression was used for univariate and multivariate analyses of prognostic factors.

RESULTS

The cumulative complete response rate of all patients at 24 months was 53.2%, and those of patients with MM, breast cancer and prostate cancer were 27.8%, 60.7% and 68.0%, respectively. Having MM was identified as an independent prognostic factor in a multivariate analysis with adjusted hazard ratios of 0.28 (95% confidence interval, 0.09-0.83).

CONCLUSION

For cancer patients with ONJ related to zoledronic acid, patients with MM endure a worse treatment outcome.

Epidemiology of spinal cord and column tumors

The spine is a frequent location for metastatic disease. As local control of primary tumor pathology continues to improve, survival rates improve and, by extension, the opportunity for metastasis increases. Breast, lung, and prostate cancer are the leading contributors to spinal metastases. Spinal metastases can manifest as bone pain, pathologic fractures, spinal instability, nerve root compression, and, in its most severe form, spinal cord compression. The global extent of disease, the spinal burden, neurologic status, and life expectancy help to categorize patients as to their candidacy for treatment options. Efficient identification and workup of those with spinal metastases will expedite the treatment cascade and improve quality of life.

Thirty-day Outcomes After Surgery for Metastatic Bone Disease of the Extremities: An Analysis of the NSQIP Database

INTRODUCTION

Metastatic bone disease of the extremities is a notable cause of morbidity and mortality. Surgical management is not curative; therefore, risks and benefits of surgery must be carefully considered. Previous studies of surgical outcomes are limited by small sample sizes because of the rare incidence of these procedures. In this study, we aim to describe the rates of complications and mortality in the first 30 days after surgical treatment of metastatic bone disease of the femur and humerus.

METHODS

A retrospective review of patients in the National Surgical Quality Improvement Program database who underwent surgery between 2005 and 2016 was performed. Demographics, comorbidities, preoperative factors, surgical parameters, and postoperative complications were extracted. The cohort was also partitioned by surgical site and surgical modality.

RESULTS

One thousand one hundred fifty-four patients were identified, 13.1 percent of patients experienced one or more complications within 30 days of surgery. The most common complications were urinary tract infection (2.9%), deep vein thrombosis (2.5%), pneumonia (2.4%), pulmonary embolism (2.0%), and surgical site infections (1.9%). In addition, intraoperative or postoperative bleeding requiring transfusion occurred in 32.9% of cases. The rates of unplanned readmission and unplanned revision surgery were 12.7% and 4.1%, respectively. The 30-day mortality rate was 7.1%. Femur and arthroplasty cases were associated with a higher risk of bleeding requiring transfusion. Prophylactic stabilization was associated with a lower risk of unplanned revision surgery (P = 0.015) and a lower overall complication rate (P < 0.0001).

CONCLUSION

Our study demonstrates a higher 30-day mortality rate than previously reported. In additon, prophylactic stabilization of impending pathologic fractures may be associated with a lower risk of complications and unplanned revision surgery. The National Surgical Quality Improvement Program or other large database reports can help surgeons counsel patients appropriately regarding the risks and benefits of surgery.

Risk factors and nomogram for newly diagnosis of bone metastasis in bladder cancer: A SEER-based study

Bladder cancer (BC) is the second most common urogenital malignant tumor. Bone metastasis (BM) is not common in BC patients, and there are only few studies on it. However, it was found in a clinical study that BM was related to the occurrence of bone complications and the decrease in survival rate. Early diagnosis of BC with BM is important for timely intervention and prevention of pathological fracture, which is of great significance for improving the quality of life of BC patients. This study aimed to identify the risk factors of BM and establish a predictive nomogram for the early diagnosis of BM in BC.The medical records of the newly diagnosed BC patients were extracted from the database of Surveillance, Epidemiology, and End Results (SEER) during 2010 to 2016. The risk factors of BC with BM were evaluated using multivariate logistic regression analysis. Then a nomogram was established to predict the risk of BC with BM.This study included 35,506 patients identified in the SEER database as diagnosed with BC, 796 of whom had BM. Grade, T stage, N stage, liver metastasis, race, brain metastasis, lung metastasis, histologic type, primary site, and age were risk predictors of BC with BM. Using Harrell's concordance index, calibration curve, and decision curve analyses, we found that the nomogram for predicting the risk of BC metastasis performed well internally.The nomogram developed in this study is expected to become an accurate and personalized tool for predicting risks of BC with BM in patients. It may be of great significance for clinicians to formulate more reasonable and effective treatment strategies. As the first study, we established a predictive nomogram for BC with BM based on the retrospective analysis of data of BC patients from the SEER database.

Bone Tropism in Cancer Metastases

Bone is a frequent site of metastases in many cancers. Both bone properties and the tumor-intrinsic traits are associated with the metastatic propensity to bone (i.e., the bone tropism). Whereas an increasing body of mechanistic studies expanded our understanding on bone tropism, they also revealed complexity across the bone lesions originated from different cancer types. In this review, we will discuss the physical, chemical, and biological properties of bone microenvironment, identify potential players in every stage of bone metastases, and introduce some of the known mechanisms regulating the bone colonization. Our objectives are to integrate the knowledge established in different biological contexts and highlight the determinants of bone tropism.

Extracellular Vesicles in Bone Metastasis: Key Players in the Tumor Microenvironment and Promising Therapeutic Targets

Extracellular vesicles (EVs) are lipid membranous vesicles that are released from every type of cell. It has become clear that EVs are involved in a variety of biological phenomena, including cancer progression, and play critical roles in intracellular communication through the horizontal transfer of cellular cargoes such as proteins, DNA fragments, RNAs including mRNA and non-coding RNAs (microRNA, piRNA, and long non-coding RNA) and lipids. The most common cause of death associated with cancer is metastasis. Recent investigations have revealed that EVs are deeply associated with metastasis. Bone is a preferred site of metastasis, and bone metastasis is generally incurable and dramatically affects patient quality of life. Bone metastasis can cause devastating complications, including hypercalcemia, pathological fractures, spinal compression, and bone pain, which result in a poor prognosis. Although the mechanisms underlying bone metastasis have yet to be fully elucidated, increasing evidence suggests that EVs in the bone microenvironment significantly contribute to cancer progression and cancer bone tropism. Emerging evidence on EV functions in bone metastasis will facilitate the discovery of novel treatments. In this review, we will discuss the remarkable effects of EVs, especially on the tumor microenvironment in bone.

Bone metastases: a comprehensive review of the literature

The last report of the World Health Organization (WHO) stated that approximately four million people experience bone pain due to malignant diseases. Among them, metastatic bone pain is one of the most important sources of complaint. The estimated median survival in the presence of bone metastases ranks from 10 to 12 weeks. Bone represents a potential target of distant metastases for the majority of malignant tumours. However, the exact incidence of bone metastases is unknown. Bone metastases have an important socio-economic impact, and due to the enhancement of the overall survivorship, their incidence is increasing. Malignant neoplasms such as lung, thyroid, renal cancer, multiple myeloma, and melanoma often metastasize to the bone. Bone metastases commonly localize to the spinal column, pelvis, shoulder, and distal femur. The proper treatment for painful skeletal metastases is still unknown. Hence, the purpose of this review of the literature was to update current evidence concerning the aetiogenesis, biological behaviour, and treatment algorithms for painful skeletal metastases.

BMP2 signalling activation enhances bone metastases of non-small cell lung cancer

Distant metastases occur when non‐small cell lung cancer (NSCLC) is at late stages. Bone metastasis is one of the most frequent metastases of NSCLC and leads to poor prognosis. It has been reported that high expression of BMP2 in NSCLC correlates with poor survival, but whether BMP2 contributes to NSCLC bone metastasis remains largely unknown. The activation of BMP signalling is found in metastatic bone tumours of mice Lewis lung carcinoma and predicts poor survival in human NSCLC. BMP2 signalling activation can enhance bone metastasis of Lewis lung carcinoma. Moreover, BMP2 secreted by stroma fibroblasts can promote the migration and invasion of NSCLC cells. Besides, in combination with pre‐osteoblast and LLCs, BMP2 could enhance the differentiation of macrophages into osteoclasts to play roles in the osteolytic mechanism of NSCLC bone metastasis. Interestingly, NSCLC cells can also enrich BMP2 to pre‐osteoblasts to function in the osteoblastic mechanism. Our results firstly demonstrate the detailed mechanisms about what roles BMP2 signalling play in enhancing NSCLC bone metastases. These findings provide a new potential therapy choice for preventing bone metastases of NSCLC via the inhibition of BMP2 signalling.

Secreted BMP antagonists and their role in cancer and bone metastases

Bone morphogenetic proteins (BMPs) are multifunctional secreted cytokines that act in a highly context-dependent manner. BMP action extends beyond the induction of cartilage and bone formation, to encompass pivotal roles in controlling tissue and organ homeostasis during development and adulthood. BMPs signal via plasma membrane type I and type II serine/threonine kinase receptors and intracellular SMAD transcriptional effectors. Exquisite temporospatial control of BMP/SMAD signalling and crosstalk with other cellular cues is achieved by a series of positive and negative regulators at each step in the BMP/SMAD pathway. The interaction of BMP ligand with its receptors is carefully controlled by a diverse set of secreted antagonists that bind BMPs and block their interaction with their cognate BMP receptors. Perturbations in this BMP/BMP antagonist balance are implicated in a range of developmental disorders and diseases, including cancer. Here, we provide an overview of the structure and function of secreted BMP antagonists, and summarize recent novel insights into their role in cancer progression and bone metastasis. Gremlin1 (GREM1) is a highly studied BMP antagonist, and we will focus on this molecule in particular and its role in cancer. The therapeutic potential of pharmacological inhibitors for secreted BMP antagonists for cancer and other human diseases will also be discussed.

Efficient Bone Metastasis Diagnosis in Bone Scintigraphy Using a Fast Convolutional Neural Network Architecture

(1) Background: Bone metastasis is among diseases that frequently appear in breast, lung and prostate cancer; the most popular imaging method of screening in metastasis is bone scintigraphy and presents very high sensitivity (95%). In the context of image recognition, this work investigates convolutional neural networks (CNNs), which are an efficient type of deep neural networks, to sort out the diagnosis problem of bone metastasis on prostate cancer patients; (2) Methods: As a deep learning model, CNN is able to extract the feature of an image and use this feature to classify images. It is widely applied in medical image classification. This study is devoted to developing a robust CNN model that efficiently and fast classifies bone scintigraphy images of patients suffering from prostate cancer, by determining whether or not they develop metastasis of prostate cancer. The retrospective study included 778 sequential male patients who underwent whole-body bone scans. A nuclear medicine physician classified all the cases into three categories: (a) benign, (b) malignant and (c) degenerative, which were used as gold standard; (3) Results: An efficient and fast CNN architecture was built, based on CNN exploration performance, using whole body scintigraphy images for bone metastasis diagnosis, achieving a high prediction accuracy. The results showed that the method is sufficiently precise when it comes to differentiate a bone metastasis case from other either degenerative changes or normal tissue cases (overall classification accuracy = 91.61% ± 2.46%). The accuracy of prostate patient cases identification regarding normal, malignant and degenerative changes was 91.3%, 94.7% and 88.6%, respectively. To strengthen the outcomes of this study the authors further compared the best performing CNN method to other popular CNN architectures for medical imaging, like ResNet50, VGG16, GoogleNet and MobileNet, as clearly reported in the literature; and (4) Conclusions: The remarkable outcome of this study is the ability of the method for an easier and more precise interpretation of whole-body images, with effects on the diagnosis accuracy and decision making on the treatment to be applied.

Current concepts in the surgical treatment of skeletal metastases

Symptomatic metastatic bone disease affects a large proportion of patients with malignant tumours and significantly impairs patients’ quality of life. There are still controversies regarding both surgical indications and methods, mainly because of the relatively few high-quality studies in this field. Generally, prosthetic reconstruction has been shown to result in fewer implant failures and should be preferred in patients with a good prognosis. Survival estimation tools should be used as part of preoperative planning. Adjuvant treatment, which relies on radiotherapy and inhibition of osteoclast function may also offer symptomatic relief and prevent implant failure. In this review we discuss the epidemiology, indications for surgery, preoperative planning, surgical techniques and adjuvant treatment of metastatic bone disease.

Fracture risk assessment and clinical decision making for patients with metastatic bone disease

Metastatic breast, prostate, lung, and other cancers often affect bone, causing pain, increasing fracture risk, and decreasing function. Management of metastatic bone disease (MBD) is clinically challenging when there is potential but uncertain risk of pathological fracture. Management of MBD has become a major focus within orthopedic oncology with respect to fracture and impending fracture care. If impending skeletal-related events (SREs), particularly pathologic fracture, could be predicted, increasing evidence suggests that prophylactic surgical treatment improves patient outcomes. However, current fracture risk assessment and radiographic metrics do not have high accuracy and have not been combined with relevant patient survival tools. This review first explores the prevalence, incidence, and morbidity of MBD and associated SREs for different cancer types. Strengths and limitations of current fracture risk scoring systems for spinal stability and long bone fracture are highlighted. More recent computed tomography (CT)-based structural rigidity analysis (CTRA) and finite element (FE) analysis methods offer advantages of increased specificity (true negative rate), but are limited in availability. Other fracture prediction approaches including parametric response mapping and positron emission tomography/computed tomography measures show early promise. Substantial new information to inform clinical decision-making includes measures of survival, clinical benefits, and economic analysis of prophylactic treatment compared to after-fracture stabilization. Areas of future research include use of big data and machine learning to predict SREs, greater access and refinement of CTRA/FE approaches, combination of clinical survival prediction tools with radiographically based fracture risk assessment, and net benefit analysis for fracture risk assessment and prophylactic treatment.

Integrating the immune microenvironment of prostate cancer induced bone disease

Prostate cancer (PCa) is the most frequently diagnosed cancer for men in the U.S. but does not impede patient survival until the disease is metastatic. Metastatic lesions most frequently occur in the bone, which exhibits a distinct microenvironment of immune and bone cell populations. Advances in the diagnosis and treatment of primary PCa allow for the use of tailored therapeutic approaches based on biomarkers, protein expression, and histopathology. Understanding the molecular and cellular characteristics of primary tumors has advanced therapeutic development and survival for patients with PCa. Personalized medicine has only recently emerged for the treatment of metastatic bone lesions. Tumor induced bone disease (TIBD) in patients with PCa can be classified into lytic, blastic, or mixed pathologies, with most patients exhibiting the blastic phenotype. Progress has been made in treating TIBD, but metastatic PCa has yet to be cured. Immune checkpoint inhibitors have exhibited limited responses in immunosuppressive PCa tumors, but have yet to be assessed in metastatic sites which may be susceptible to an increased inflammatory response. Recent discoveries have uncovered distinct tumor microenvironments (TMEs) of blastic and lytic bone metastases from patients with PCa, identifying actionable targets for therapeutic applications, including immune checkpoint inhibitors and targeted therapeutics. Enrichment for macrophages and T cells in patient samples suggests metastatic sites may be reappraised as immunologically targetable, despite their immunologically "cold" primary tumors. The practice of performing bone biopsies will help identify unique cellular and protein targets in the bone TME that can guide therapy decisions.

Distribution of Femoral Metastases; Potential Role for Extended FDG PET/CT Scanning

This study investigates the distribution of femoral metastases in cancer patients, specifically addressing the incidence of distal femoral metastases. PET/CT examinations routinely extend only to mid-thigh level, precluding detection of distal metastases. We found a total of 208 femoral metastases in 112 patients. 30% had distal femoral metastases in addition to other areas of involvement. 7% of patients with femoral metastases had only distal femur disease. 6 patients had distal pathologic fractures. Exclusion of the distal femur during PET/CT may result in a missed or delayed diagnosis that could contribute to the development of a pathologic fracture with increased morbidity.

Bone metastases in thyroid cancer

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Osseous metastases (OMs) occur in only 4% of all thyroid cancer patients but are associated with greatly increased morbidity and mortality.

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OMs are about twice as frequent in follicular, hurthle cell, and medullary thyroid cancers as compared to papillary thyroid cancers.

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OMs are often lytic, triggered via activation of osteoclasts by tumor cells in a “vicious cycle”.

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OMs are often initially asymptomatic, but associated with eventual skeletal related events in >75%.

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Early identification of OMs, preemptive treatment with antiresorptive agents, and aggressive treatment of focal lesions before crisis are key.

Whereas preemptive screening for the presence of lymph node and lung metastases is standard-of-care in thyroid cancer patients, bone metastases are less well studied and are often neglected in thyroid cancer patient surveillance. Bone metastases in thyroid cancer are, however, independently associated with poor/worse prognosis with a median overall survival from detection of only 4 years despite an otherwise excellent prognosis for the vast majority of thyroid cancer patients. In this review we summarize the state of current knowledge as pertinent to bony metastatic disease in thyroid cancer, including clinical implications, impacts on patient function and quality of life, pathogenesis, and therapeutic opportunities, proposing approaches to patient care accordingly. In particular, bone metastasis pathogenesis appears to reflect cooperatively between cancer and the bone microenvironment creating a “vicious cycle” of bone destruction rather than due exclusively to tumor invasion into bone. Additionally, bone metastases are more frequent in follicular and medullary thyroid cancers, requiring closer bone surveillance in patients with these histologies. Emerging data also suggest that treatments such as multikinase inhibitors (MKIs) can be less effective in controlling bone, as opposed to other (e.g. lung), metastases in thyroid cancers, making special attention to bone critical even in the setting of active MKI therapy. Although locoregional therapies including surgery, radiotherapy and ablation play important roles in palliation, antiresorptive agents including bisphosphonates and denosumab appear individually to delay and/or lessen skeletal morbidity and complications, with dosing frequency of every 3 months appearing optimal; their early application should therefore be strongly considered.

A Deep-Learning Approach for Diagnosis of Metastatic Breast Cancer in Bones from Whole-Body Scans

(1) Background: Bone metastasis is one of the most frequent diseases in breast, lung and prostate cancer; bone scintigraphy is the primary imaging method of screening that offers the highest sensitivity (95%) regarding metastases. To address the considerable problem of bone metastasis diagnosis, focused on breast cancer patients, artificial intelligence methods devoted to deep-learning algorithms for medical image analysis are investigated in this research work; (2) Methods: Deep learning is a powerful algorithm for automatic classification and diagnosis of medical images whereas its implementation is achieved by the use of convolutional neural networks (CNNs). The purpose of this study is to build a robust CNN model that will be able to classify images of whole-body scans in patients suffering from breast cancer, depending on whether or not they are infected by metastasis of breast cancer; (3) Results: A robust CNN architecture is selected based on CNN exploration performance for bone metastasis diagnosis using whole-body scan images, achieving a high classification accuracy of 92.50%. The best-performing CNN method is compared with other popular and well-known CNN architectures for medical imaging like ResNet50, VGG16, MobileNet, and DenseNet, reported in the literature, providing superior classification accuracy; and (4) Conclusions: Prediction results show the efficacy of the proposed deep learning approach in bone metastasis diagnosis for breast cancer patients in nuclear medicine.

Bone Metastasis: Current State of Play

Bone metastasis (BM) in cancer remains a critical issue because of its associated clinical and biological complications. Moreover, BM can alter the quality of life and survival rate of cancer patients. Growing evidence suggests that bones are a fertile ground for the development of metastasis through a "vicious circle" of bone resorption/formation and tumor growth. This review aims to outline the current major issues in the diagnosis and management of BM in the most common types of osteotropic cancers and describe the mechanisms and effects of BM. First, we discuss the incidence of BM through the following questions: Are we witnessing an increase in incidence, and are we now better equipped with modern imaging techniques? Is the advent of efficient bone resorption inhibitors affecting the bigger picture of BM management? Second, we discuss the potential effects of cancer progression and well-prescribed drugs, such as multitarget tyrosine kinase inhibitors, inhibitors of the mammalian target of rapamycin, and immune checkpoint inhibitors, on BM. Finally, we examine the duality of the effects of some therapies that may help in cancer treatment but may also contribute to further BM.

When Back Pain Turns Deadly: An Unusual Presentation of Lung Cancer

Back pain is a common presenting concern in physician offices and emergency departments alike, with etiologies ranging from minor injuries to severe life-threatening illnesses. This case details the clinical course of a 68-year-old former smoker with no pulmonary symptoms who presented with back pain multiple times before developing cord compression syndrome and being diagnosed with non-small cell lung cancer (NSCLC). It demonstrates the importance of lung cancer screening and the necessity of monitoring for red flags in cases of back pain.

What Is the Role of Interleukins in Breast Cancer Bone Metastases? A Systematic Review of Preclinical and Clinical Evidence

Breast cancer cells produce stimulators of bone resorption known as interleukins (ILs). However, data on the functional roles of ILs in the homing of metastatic breast cancer to bone are still fragmented. A systematic search was carried out in three databases (PubMed, Scopus, Web of Science Core Collection) to identify preclinical reports, and in three clinical registers (ClinicalTrials.gov, World Health Organization (WHO) International Clinical Trials Registry Platform, European Union (EU) Clinical Trials Register) to identify clinical trials, from 2008 to 2019. Sixty-seven preclinical studies and 11 clinical trials were recognized as eligible. Although preclinical studies identified specific key ILs which promote breast cancer bone metastases, which have pro-metastatic effects (e.g., IL-6, IL-8, IL-1β, IL-11), and whose inhibition also shows potential preclinical therapeutic effects, the clinical trials focused principally on ILs (IL-2 and IL-12), which have an anti-metastatic effect and a potential to generate a localized and systemic antitumor response. However, these clinical trials are yet to post any results or conclusions. This inconsistency indicates that further studies are necessary to further develop the understanding of cellular and molecular relations, as well as signaling pathways, both up- and downstream of ILs, which could represent a novel strategy to treat tumors that are resistant to standard care therapies for patients affected by breast cancer bone disease.

Mild hyperthermia by MR-guided focused ultrasound in an ex vivo model of osteolytic bone tumour: optimization of the spatio-temporal control of the delivered temperature

BACKGROUND

Magnetic resonance guided focused ultrasound was suggested for the induction of deep localized hyperthermia adjuvant to radiation- or chemotherapy. In this study we are aiming to validate an experimental model for the induction of uniform temperature elevation in osteolytic bone tumours, using the natural acoustic window provided by the cortical breakthrough.

MATERIALS AND METHODS

Experiments were conducted on ex vivo lamb shank by mimicking osteolytic bone tumours. The cortical breakthrough was exploited to induce hyperthermia inside the medullar cavity by delivering acoustic energy from a phased array HIFU transducer. MR thermometry data was acquired intra-operatory using the proton resonance frequency shift (PRFS) method. Active temperature control was achieved via a closed-loop predictive controller set at 6 °C above the baseline. Several beam geometries with respect to the cortical breakthrough were investigated. Numerical simulations were used to further explain the observed phenomena. Thermal safety of bone heating was assessed by cross-correlating MR thermometry data with the measurements from a fluoroptic temperature sensor inserted in the cortical bone.

RESULTS

Numerical simulations and MR thermometry confirmed the feasibility of spatio-temporal uniform hyperthermia (± 0.5 °C) inside the medullar cavity using a fixed focal point sonication. This result was obtained by the combination of several factors: an optimal positioning of the focal spot in the plane of the cortical breakthrough, the direct absorption of the HIFU beam at the focal spot, the "acoustic oven effect" yielded by the beam interaction with the bone, and a predictive temperature controller. The fluoroptical sensor data revealed no heating risks for the bone and adjacent tissues and were in good agreement with the PRFS thermometry from measurable voxels adjacent to the periosteum.

CONCLUSION

To our knowledge, this is the first study demonstrating the feasibility of MR-guided focused ultrasound hyperthermia inside the medullar cavity of bones affected by osteolytic tumours. Our results are considered a promising step for combining adjuvant mild hyperthermia to external beam radiation therapy for sustained pain relief in patients with symptomatic bone metastases.

Clinical outcomes associated with pathogenic genomic instability mutations in prostate cancer: a retrospective analysis of US pharmacy and medical claims data

Background: Prostate cancer (PC) is a clinically heterogenous disease, and genetic mutations may be useful for patient risk stratification. This retrospective cohort study compared clinical outcomes, pharmacy use, and outpatient resource use in PC patients with and without pathogenic genomic instability mutations, including DNA repair deficiency (DRD) mutations and those in TP53, PTEN, and RB1. Methods: Patients ≥18 years newly-diagnosed with PC between June 2011-March 2016 were identified in medical and prescription claims databases linked to a genomic dataset. All-cause and PC-specific pharmacy use and outpatient resource use (office visits, laboratory tests, radiology examinations, and radiation therapies) over 1, 2, and 3 years and time to evidence of disease progression after PC diagnosis, based on secondary cancer diagnosis codes and treatments received, were evaluated in mutation carriers with ≥1 of 24 gene mutations and in a sub-set of DRD gene mutation carriers, with each compared to non-mutation carriers. Results: Mutation carriers (n = 274) and non-mutation carriers (n = 74) had similar demographic and clinical features. Non-mutation carriers had lower risks of developing metastasis and castration-resistant PC than mutation carriers (hazard ratio [HR] = 0.7, 95% CI = 0.5-0.9; HR = 0.5, 95% CI = 0.3-0.9, respectively) and DRD mutation carriers (HR = 0.5, 95% CI = 0.3-0.7; HR = 0.4, 95% CI = 0.2-0.7, respectively). Compared to non-mutation carriers, mutation carriers had more all-cause pharmacy claims over 2 years of follow-up (74.4 vs 59.1, p = 0.04) and more PC-specific pharmacy claims over 2 years (11.1 vs 6.5, p = 0.01) and 3 years (17.9 vs 9.8, p = 0.01) of follow-up. No differences were observed in outpatient resource use during the follow-up period by mutation status. Conclusion: PC patients carrying ≥1 pathogenic DNA instability mutation, and DRD mutation carriers specifically, had higher clinical burden than non-mutation carriers. Targeted therapies for these patients are needed to reduce clinical burden and associated healthcare resource utilization.

Dose-Dependent Growth Delay of Breast Cancer Xenografts in the Bone Marrow of Mice Treated with 223Ra: The Role of Bystander Effects and Their Potential for Therapy

The role of radiation-induced bystander effects in radiation therapy remains unclear. With renewed interest in therapy with α-particle emitters, and their potential for sterilizing disseminated tumor cells (DTCs), it is critical to determine the contribution of bystander effects to the overall response so they can be leveraged for maximum clinical benefit. Methods: Female Foxn1_nu athymic nude mice were administered 0, 50, or 600 kBq/kg ²²³RaCl₂ to create bystander conditions. At 24 hours after administration, MDA-MB-231 or MCF-7 human breast cancer cells expressing luciferase were injected into the tibial marrow compartment. Tumor burden was tracked weekly via bioluminescence. Results: The MDA-MB-231 xenografts were observed to have a 10-day growth delay in the 600 kBq/kg treatment group only. In contrast, MCF-7 cells had 7- and 65-day growth delays in the 50 and 600 kBq/kg groups, respectively. Histologic imaging of the tibial marrow compartment, α-camera imaging, and Monte Carlo dosimetry modeling revealed DTCs both within and beyond the range of the α-particles emitted from ²²³Ra in bone for both MCF-7 and MDA-MB-231 cells. Conclusion: Taken together, these results support the participation of ²²³Ra-induced antiproliferative/cytotoxic bystander effects in delayed growth of DTC xenografts. They indicate that the delay depends on the injected activity and therefore is dose-dependent. They suggest using ²²³RaCl₂ as an adjuvant treatment for select patients at early stages of breast cancer.

Anti-Tumor Effects of Low Dose Zoledronate on Lung Cancer-Induced Spine Metastasis

Zoledronate (Zol) is an anti-resorptive/tumoral agent used for the treatment of many cancers including spinal bone metastasis. High systemic administration of a single dose is now the standard clinical care, yet it has been associated with several side effects. Here, we aimed to evaluate the effects of lower doses Zol on lung cancer and lung cancer-induced bone metastasis cells over a longer time period. Human lung cancer (HCC827) and three bone metastases secondary to lung cancer (BML1, BML3 and BML4) cells were treated with Zol at 1, 3 and 10 µM for 7 days and then assessed for cell proliferation, migration, invasion and apoptosis. Low Zol treatment significantly decreased cell proliferation (1, 3 and 10 µM), migration (3 and 10 µM) and invasion (10 µM) while increasing apoptosis (10 µM) in lung cancer and metastatic cells. Our data exploits the potential of using low doses Zol for longer treatment periods and reinforces this approach as a new therapeutic regimen to impede the development of metastatic bone cancer while limiting severe side effects following high doses of systemic drug treatment.

The Bone Extracellular Matrix as an Ideal Milieu for Cancer Cell Metastases

Bone is a preferential site for cancer metastases, including multiple myeloma, prostate, and breast cancers.The composition of bone, especially the extracellular matrix (ECM), make it an attractive site for cancer cell colonization and survival. The bone ECM is composed of living cells embedded within a matrix composed of both organic and inorganic components. Among the organic components, type I collagen provides the tensile strength of bone. Inorganic components, including hydroxyapatite crystals, are an integral component of bone and provide bone with its rigidity. Under normal circumstances, two of the main cell types in bone, the osteoblasts and osteoclasts, help to maintain bone homeostasis and remodeling through cellular communication and response to biophysical signals from the ECM. However, under pathological conditions, including osteoporosis and cancer, bone remodeling is dysregulated. Once in the bone matrix, disseminated tumor cells utilize normal products of bone remodeling, such as collagen type I, to fuel cancer cell proliferation and lesion outgrowth. Models to study the complex interactions between the bone matrix and metastatic cancer cells are limited. Advances in understanding the interactions between the bone ECM and bone metastatic cancer cells are necessary in order to both regulate and prevent metastatic cancer cell growth in bone.

Quantitative imaging of platinum-based antitumor complexes in bone tissue samples using LA-ICP-MS

There is a need for effective medication against bone metastases because todays drugs are not able to penetrate the bone and reach the affected areas. To analyze if current or future platinum-containing drugs are able to achieve this, a quantitative imaging method is urgently needed. In this study, the platinum distribution in thin sections of mice tibia was determined using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in a spatially resolved manner. The hard bone tissue visible in microscopic images and signals found for calcium and phosphorous recorded via LA-ICP-MS and micro X-ray fluorescence spectroscopy (μXRF) correlate well. Furthermore, the platinum concentration was quantified using polymer-based matrix-matched standards. A limit of detection of 6 μg/g and a linearity of almost three decades could be achieved. Concentrations surpassing 300 μg/g could be found in the tibia samples. The method presented herein is a powerful approach for the visualization and quantification of platinum. As such, this method is a valuable tool to unravel the mechanism of delivery and optimize the therapeutic potency of platinum-containing drugs targeting bone diseases like bone metastases.

Bone scan index as metastatic bone disease quantifier and predictor of radium-223-dichloride biochemical response

OBJECTIVES

This work aims to assess whether the biochemical response of radium-223-dichloride treatment can be predicted based on the pretherapy bone scan, and consequently if bone scan index (BSI) and maximum lesion intensity have a place as alternatives or as complements to extent of bone disease (EOBD) scoring in predicting biochemical response to treatment. Many cases of advanced prostate cancer have evidence of bone metastasis. Accurate EOBD quantification could help predict the response to radium-223-dichloride therapy. Current EOBD score is simple to use but does not consider size, intensity or localisation of lesion BSI might be more suitable for stratification of bone metastases.

PATIENTS AND METHODS

Bone scans (n=20) preceding radium-223-dichloride treatment for prostate cancer were assessed retrospectively using automated BSI software (EXINI) and by assessing maximum counts per lesion. Results were then compared to total alkaline phosphatase (ALP) as a measure of biochemical response to therapy using linear regressions and to their EOBD scores using box plot analysis.

RESULTS

Moderate correlation was found between ALP response and maximum lesion intensity (R=0.41) and BSI (R=0.46). Strong correlation (R=0.71) was found between baseline ALP and BSI and between lesion number and BSI (R=0.60). Visual assessment of EOBD score was found to correlate well with baseline ALP and maximum ALP response.

CONCLUSION

BSI is a useful asset in stratification of patients with metastatic bone disease. It may also have a place in prediction of biochemical response.

Low-dose zoledronate for the treatment of bone metastasis secondary to prostate cancer

Background

Bisphosphonates (BPs) including zoledronate (zol) have become standard care for bone metastases as they effectively inhibit tumor-induced osteolysis and associated pain. Several studies have also suggested that zol has direct anti-tumor activity. Systemic administration at high doses is the current approach to deliver zol, yet it has been associated with debilitating side effects. Local therapeutic delivery offers the ability to administer much lower total dosage, while at the same time maintaining sustained high-local drug concentration directly at the target treatment site. Here, we aimed to assess effects of lower doses of zol on bone metastases over a longer time.

Methods

Prostate cancer cell line LAPC4 and prostate-induced bone metastasis cells were treated with zol at 1, 3 and 10 µM for 7 days. Following treatment, cell proliferation was assessed using Almarblue^®, Vybrant MTT^®, and Live/Dead^® viability/cytotoxicity assays. Additionally, cell migration and invasion were carried out using Falcon™ cell culture inserts and Cultrex^® 3D spheroid cell invasion assays respectively.

Results

We show that treatment with 3–10 µM zol over 7-days significantly decreased cell proliferation in both the prostate cancer cell line LAPC4 and cells from spine metastases secondary to prostate cancer. Using the same low-dose and longer time course for treatment, we demonstrate that 10 µM zol also significantly inhibits tumor cell migration and 3D-cell growth/invasion.

Conclusions

This project harnesses the potential of using zol at low doses for longer treatment periods, which may be a viable treatment modality when coupled with biomaterials or biodevices for local delivery.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0745-x) contains supplementary material, which is available to authorized users.

Early Clinical and Economic Outcomes of Prophylactic and Acute Pathologic Fracture Treatment

INTRODUCTION:

Pathologic fractures often contribute to adverse events in metastatic bone disease, and prophylactic fixation offers to mitigate their effects. This study aims to analyze patient selection, complications, and in-hospital costs that are associated with prophylactic fixation compared with traditional acute fixation after completed fracture.

MATERIALS AND METHODS:

The Nationwide Inpatient Sample database was queried from 2002 to 2014 for patients with major extremity pathologic fractures. Patients were divided by fixation technique (prophylactic or acute) and fracture location (upper or lower extremity). Patient demographics, comorbidities, complications, hospitalization length, and hospital charges were compared between cohorts. Preoperative variables were analyzed for potential confounding, and χ2 tests and Student’s t tests were used to compare fixation techniques.

RESULTS:

Cumulatively, 43,920 patients were identified, with 14,318 and 28,602 undergoing prophylactic and acute fixation, respectively. Lower extremity fractures occurred in 33,582 patients, and 10,333 patients had upper extremity fractures. A higher proportion of prophylactic fixation patients were white ( P = .043), male ( P = .046), age 74 years or younger ( P < .001), and privately insured ( P < .001), with decreased prevalence of obesity ( P = .003) and/or preoperative renal disease ( P = .008). Prophylactic fixation was also associated with decreased peri- and postoperative blood transfusions ( P < .001), anemia ( P < .001), acute renal failure ( P = .010), and in-hospital mortality ( P = .031). Finally, prophylactic fixation had decreased total charges (−$3,405; P = .001), hospitalization length ( P = .004), and extended length of stay (greater than 75th percentile; P = .012).

CONCLUSION:

Prophylactic fixation of impending pathologic fractures is associated with decreased complications, hospitalization length, and total charges, and should be considered in appropriate patients.

Targeted Nanomedicine to Treat Bone Metastasis

Bone metastases are common complications of solid tumors, particularly those of the prostate, breast, and lungs. Bone metastases can lead to painful and devastating skeletal-related events (SREs), such as pathological fractures and nerve compressions. Despite advances in treatment for cancers in general, options for bone metastases remain inadequate and generally palliative. Anticancer drugs (chemotherapy and radiopharmaceuticals) do not achieve therapeutic concentrations in the bone and are associated with dose-limiting side effects to healthy tissues. Nanomedicines, with their tunable characteristics, have the potential to improve drug targeting to bone metastases while decreasing side effects for their effective treatment. In this review, we present the current state of the art for nanomedicines to treat bone metastases. We also discuss new treatment modalities enhanced by nanomedicine and their effects on SREs and disease progression.

A brief instrument to measure health-related quality-of-life in patients with bone metastasis: validation of the German version of Bone Metastases Quality-of-Life-10 (BOMET-QoL-10)

AIMS

This prospective, epidemiologic study was designed to translate the original Spanish Bone Metastases Quality-of-Life-10 (BOMET-QoL-10) questionnaire and undertake a validation of the translated German version of BOMET-QoL-10 in Germany to assess health-related quality-of-life (HRQoL) in patients with bone metastases (BM).

METHODS

The translation process included forward and backward translations, and a linguistic validation. Patients aged ≥18 years with histological confirmation of cancer, diagnosed with BM, life expectancy ≥6 months, and fluency in German were eligible for this study (enrolled consecutively in 33 outpatient centers in Germany). Patients were given the German version of BOMET-QoL-10, together with the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire QLQ-C30 and EORTC QLQ-BM22 questionnaires at inclusion, 6 weeks, 3 months, and 6 months after inclusion. A debriefing questionnaire was administered at inclusion to determine patient acceptability and understanding.

RESULTS

Data include 364 patients with BM (median age = 68 years; females = 71.7%). The BOMET-QoL-10 is brief and clear (median completion time = 5 minutes; >90% of patients completed the questionnaire without assistance). The BOMET-QoL-10 forms only one overall scale. All 10 items showed a substantial correlation with the first factor (factor loading, range = 0.58-0.86). BOMET-QoL-10 exhibits high internal consistency and reproducibility (Cronbach's alpha = 0.91; intra-class correlation coefficient = 0.76). BOMET-QoL-10 showed significant correlations (range = 0.69-0.79) both with EORTC QLQ-C30 and EORTC QLQ-BM22 within the functioning (physical, social, interference) and symptom (fatigue, pain) scales, displayed significant sensitivity to change in EORTC QLQ-BM22 scores, and proved the potential ability to detect change in HRQoL in patients with different disease status.

LIMITATIONS

There was a high proportion of females in this study, which might represent a limitation.

CONCLUSIONS

The German version of BOMET-QoL-10 is a valid, reliable, brief, and clear instrument able to measure HRQoL in patients with BM.

Novel bisphosphonates with antiresorptive effect in bone mineralization and osteoclastogenesis

Bisphosphonates such as zoledronic, alendronic and risedronic acids are a class of drugs clinically used to prevent bone density loss and osteoporosis. Novel P-C-P bisphosphonates were synthesized for targeting human farnesyl pyrophosphate synthase (hFPPS) and human geranylgeranyl pyrophosphate synthase (hGGPPS), key enzymes of the mevalonate pathway, and capable of anti-proliferative action on a number of cell lines (PC3, MG63, MC3T3, RAW 264.7, J774A.1, bone marrow cells and their co-colture with PC3) involved in bone homeostasis, bone formation and death. Among sixteen compounds, [1-hydroxy-2-(pyrimidin-2-ylamino)ethane-1,1-diyl]bis(phosphonic acid) (10) was effective in reducing PC3 and RAW 264.7 cell number in crystal-violet and cell-dehydrogenase activity assays at 100 μM concentration. 10 reduced differentiated osteoclasts number similarly with zoledronic acid in osteoclastogenesis assay. At nanomolar concentrations, 10 was more effective than zoledronic acid in inducing mineralization in MC3T3 and murine bone marrow cells. Further, 10 significantly inhibited the activity of hFPPS showing an IC₅₀ of 0.31 μM and a remarkable hydroxyapatite binding of 90%. Docking calculations were performed identifying putative interactions between some representative novel bisphosphonates and both hFPPS and hGGPPS. Then, 10 was found to behave similarly or even better than zoledronic acid as a anti-resorptive agent.

The impact of radiation treatment planning technique on unplanned hospital admissions

Purpose

Treatment burdens and toxicities related to palliative radiation therapy (RT) may lead to unplanned hospital admissions (UHAs). The likelihood for these toxicities may be related to treatment technique. We compared rates of UHA between patients receiving nonconformal (2-dimensional) and conformal (3-dimensional or higher) radiation treatments to bone metastases involving the vertebral column.

Methods and materials

We retrospectively analyzed patients treated with RT for bone metastases at a single tertiary care center between 2010 and 2017. We compared rates of RT-related UHA within 90 days of receiving radiation using Cox competing risk regression models.

Results

We identified 326 patients with bone metastases involving the vertebral column, 139 of whom received radiation by nonconformal technique and 187 by conformal technique. On multivariable analysis, conformal techniques were associated with a reduced risk of 90-day UHA (hazard ratio [HR]: 0.35; 95% confidence interval [CI], 0.14-0.88). Other significant factors include hematologic cancer (HR: 0.17; 95% CI, 0.03-0.82) and baseline Eastern Cooperative Oncology Group score ≥2 (HR: 3.02; 95% CI, 1.05-8.69).

Conclusions

The utilization of conformal (non-2-dimensional) radiation treatment plans may help reduce treatment-related toxicities and consequently UHAs after palliation of bone metastases.

Necrostatin-7 suppresses RANK-NFATc1 signaling and attenuates macrophage to osteoclast differentiation

Osteoclasts play a crucial role in osteolytic bone diseases, such as osteoporosis, rheumatoid arthritis, periodontitis, Paget's disease of bone and bone metastatic tumors. Therefore, controlling osteoclast differentiation and function has been considered a promising therapeutic strategy. Here, we show that necrostatin (Nec)-7, an inhibitor of programmed necrosis, strongly suppressed receptor activator of nuclear factor (NF)-κB ligand (RANKL)-induced osteoclastogenesis and bone resorption, without compromising macrophage colony-stimulating factor (M-CSF)-supported survival and growth of osteoclast precursor cells. Accordingly, Nec-7 significantly decreased the levels of RANKL-induced osteoclastogenic marker genes, such as cathepsin K. Mechanistically, Nec-7 neither affected MAPK nor NF-κB activation; however, it strongly inhibited the RANKL receptor (RANK) to nuclear factor of activated T cells c1 (NFATc1) signaling. Lentiviral expression of RANK in bone marrow-derived macrophages significantly restored osteoclastogenesis and NFATc1 amplification in Nec-7-treated cells. In this study, we revealed that Nec-7-sensitive pathways are crucially involved in osteoclast formation and function. Investigation of the molecular mechanism(s) through which Nec-7 inhibits RANK-NFATc1 signaling axis may lead to the development of new therapeutic strategies for bone disease.

The Osteoclast in Bone Metastasis: Player and Target

Bone metastases are frequently the final fate of breast and prostate cancer patients. According to the definition of metastasis as an incurable disease, to date there are no effective treatments for tumor-associated bone metastases and this represents a real challenge for the researchers in the field. The bone is a heterogeneous environment that represents a fertile soil for tumor cells, supporting their growth. Among the different cell types present in the bone, in this review we will focus our attention on the osteoclasts, which are crucial players in the so called “vicious cycle”, a phenomenon triggered by tumor cells eventually leading to both tumor proliferation as well as bone deregulation, thus fueling the development of bone metastasis. The complex network, linking tumor cells to the bone by activating osteoclasts, represents a fruitful target for the treatment of bone metastases. In this review we will describe how tumor cells perturb the bone microenvironment by actively influencing osteoclast formation and activity. Moreover, we will describe the current antiresorptive drugs employed in the treatment of bone metastases as well as new, targeted therapies able to affect both cancer cells and osteoclasts.