Systematic Review of the Role of Stereotactic Radiotherapy for Bone Metastases

Efficacy of innovative systemic treatments in combination with radiotherapy for bone metastases: a GEMO (the European Study Group of Bone Metastases) state of the art

The management of bone metastases (BoM) requires a multidisciplinary approach to prevent complications, necessitating updated knowledge in light of the rapid advancements in systemic treatments and surgical, interventional radiology or radiation techniques. This review aims to discuss efficacy of new systemic treatments on BoM, the benefits of radiotherapy adjunction, and the optimal methods for combining them. Preliminary evidence suggesting reduced efficacy of immune checkpoint inhibitors (ICI), and several multi-kinase inhibitors regarding BoM may encourage early use of radiotherapy (RT). Systemic treatment efficacy modulation by RT and ablative RT strategies are explored. Concerns for increased side effects for several kinase inhibitors and double ICI in combination with RT imply suspending those systemic treatments during RT. Various timing strategies to combine prostate hormone therapies and RT are developed. Emerging internal vectorized radiotherapy molecules necessitate developing new combination strategies with RT. Further prospective data collection and comparative trials should be encouraged.

Radiotherapy and surgery: can this combination be further optimized for patients with metastatic spine disease?

This narrative review provides a comprehensive overview of the current status, recent advancements, and future directions in the management of metastatic spine disease using both radiotherapy and surgery. Emphasis has been put on the integrated use of radiotherapy and surgery, incorporating recent developments such as separation surgery, active dose sparing of the surgical field, and the implementation of carbon fiber-reinforced polymer implants. Future studies should explore the effects of minimizing the time between radiotherapy and surgery and investigate the potential of vertebral re-ossification after radiotherapy to obviate the need for stabilization surgery. Concerted efforts should be directed toward fostering multidisciplinary collaboration among radiation oncologists, spine surgeons, and medical oncologists.

SMILE-stereotactic multiple fraction radiotherapy for non-spine bone metastases: study protocol for a multicenter, open-label phase III randomized controlled trial

BACKGROUND

The SMILE study addresses a significant need in palliative oncology by evaluating the non-inferiority of a shortened, 3-fraction stereotactic body radiotherapy (SBRT) schedule against the traditional 5-fraction approach for non-spine bone metastases in terms of pain control. Optimizing SBRT could significantly enhance the quality of life for patients by providing effective pain relief while minimizing treatment sessions.

METHODS

This international, multicenter phase III trial will randomize 162 patients to receive either a 3-fraction regimen (9 Gy per fraction) or a standard 5-fraction regimen (7 Gy per fraction). Outcomes, assessed at 3 months post-treatment, will focus on pain response, quality of life, and control of metastasis. With a hypothesis-driven design, the study will incorporate intent-to-treat and per-protocol analyses, incorporating appropriate measures for data integrity and handling of missing information.

DISCUSSION

If the 3-fraction SBRT regimen demonstrates non-inferiority, it could streamline palliative care protocols, reduce patient burden, and set a new standard for treatment, reflecting a patient-centered approach in palliative radiation oncology.

TRIAL REGISTRATION

The trial has been registered prospectively on ClinicalTrials.gov under the identifier NCT05406063, as of May 3, 2022.

Stereotactic radiotherapy for patients with bone metastases: a selected group with low rate of radiation treatment during the last month of life?

BACKGROUND

Complex high-precision radiotherapy, such as stereotactic body radiotherapy (SBRT), should only be offered to patients with sufficiently long survival. In the context of bone metastases radiotherapy, low rates of treatment close to the end of life, e.g. last 30 days (RT30), may serve as a quality of care indicator. While traditional, pain-relieving short-course regimens have been studied comprehensively, real-world SBRT results are still limited.

METHODS

Retrospective analysis (2010-2023, n = 1117 episodes) of patients with bone metastases treated with traditional single-fraction (8 Gy × 1) or multi-fraction regimens (often 4 Gy × 5 or 3 Gy × 10) compared to stereotactic single-fraction (12-16 Gy × 1) or multi-fraction regimens.

RESULTS

Except for gender, almost all baseline variables were uneven distributed. Failure to complete fractionated radiotherapy was uncommon in the stereotactic (4%) and non-stereotactic group (3%), p = 1.0. With regard to RT30, relevant differences emerged (19% for 8-Gy single-fraction versus 0% for stereotactic single-fraction, p = 0.01). The corresponding figures were 11% for multi-fraction non-stereotactic and 2% for multi-fraction stereotactic, p = 0.08. Median overall survival was shortest after 8-Gy single-fraction irradiation (4.2 months) and longest after stereotactic multi-fraction treatment (13.9 months). Neither stereotactic radiotherapy nor multi-fraction treatment improved survival in multivariate Cox regression analysis. Factors significantly associated with longer survival included better performance status, lower LabBM score (5 standard blood test results), stable disease outside of irradiated area(s), metachronous distant metastases, longer time interval from metastatic disease to bone irradiation, and outpatient status.

CONCLUSION

The implementation of SBRT for selected patients has resulted in low rates of non-completion and RT30. Optimal selection criteria remain to be determined, but in current clinical practice we exclude patients with poor performance status, unfavorable blood test results (high LabBM score) and progressive disease sites not amenable to SBRT. Established, guideline-endorsed short-course regimens, especially 8-Gy single-fraction treatment, continue to represent an important palliative approach.

New insights into non-small cell lung cancer bone metastasis: mechanisms and therapies

Bone metastasis is a common cause of death in patients with non-small cell lung cancer (NSCLC), with approximately 30-40% of NSCLC patients eventually developing bone metastases. Bone metastasis, especially the occurrence of skeletal-related events (SREs), significantly reduces overall survival (OS) and quality of life (QoL) in patients. Although bone-targeting agents (BTAs) have been shown to reduce SREs and improve QoL in NSCLC patients with bone metastases, the prognosis for these patients remains poor. Understanding the underlying molecular pathways of bone metastasis is crucial for the development of novel therapeutic approaches. Bone metastasis is a complex, multistep process that involves interactions between tumor cells and the bone microenvironment. The bone microenvironment provides a fertile soil for tumor cells, and crosstalk among various signaling pathways and secreted factors also plays a role in regulating the occurrence and progression of bone metastasis in NSCLC. In this article, we provide a comprehensive review of the process, regulatory mechanisms, and clinical treatment in NSCLC bone metastasis, with the hope of assisting with clinical treatment.

Image-Guided Energy Ablation for Palliation of Painful Bony Metastases-A Systematic Review

PURPOSE

To analyze the effectiveness of image-guided energy ablation techniques with and without concurrent therapies in providing palliative pain relief in patients with bone metastases.

MATERIALS AND METHODS

Ovid Embase, Ovid Medline, and Pubmed were searched from inception to April 14, 2023, using search terms related to bone lesions and MeSH terms regarding ablation therapy. English peer-reviewed primary articles were included that reported pain scores following image-guided energy-based ablation of bone metastases. Exclusion criteria included nonpalliative treatment, pain scores associated with specific treatment modalities not reported, and nonmetastatic bone lesions. Mean percentage reduction in pain score was calculated.

RESULTS

Of the 1,396 studies screened, 54 were included. All but 1 study demonstrated decreased pain scores at final follow-up. Mean reductions in pain scores at final follow-up were 49% for radiofrequency (RF) ablation, 58% for RF ablation and adjunct, 54% for cryoablation (CA), 72% for cryoablation and adjunct (CA-A), 48% for microwave ablation (MWA), 81% for microwave ablation and adjunct (MWA-A), and 64% for high-intensity focused ultrasound (US). Postprocedural adverse event rates were 4.9% for RF ablation, 34.8% for RF ablation and adjunct, 9.6% for CA, 12.0% for CA-A, 48.9% for MWA, 33.5% for MWA-A, and 17.0% for high-intensity focused US.

CONCLUSIONS

Image-guided energy ablation demonstrated consistently strong reduction in pain across all modalities, with variable postprocedural adverse event rates. Owing to heterogeneity of included studies, quantitative analysis was not appropriate. Future primary research should focus on creating consistent prospective studies with established statistical power, explicit documentation, and comparison with other techniques.

Clinical outcomes of multisite moderate to high dose radiotherapy for patients with metastatic melanoma

Background and purpose

This study aimed to summarize the clinical outcomes of patients with metastatic melanoma who received high-dose radiation prior to or during systemic therapy at a single academic institution.

Methods

We identified patients with metastatic melanoma who underwent high-dose radiation therapy (HDRT) for extracranial metastases prior to or during systemic therapy from 2010 to 2018. Treatment indications included oligometastases, oligoprogression, and local control. Using the Kaplan-Meier method, we plotted overall survival (OS), progression-free survival-1 (PFS1), and PFS2. Competing risk analysis determined the cumulative incidence of local failure (LF) and the time to start or change systemic therapy (SCST). Univariate and multivariable analyses were used to identify predictive factors.

Results

We analyzed 34 patients with 79 lesions, with a median follow-up of 17.4 months. Sixty-eight percent of patients received systemic therapy after the first HDRT. The median OS was 22 months, with brain metastases before HDRT being a significant predictor in multivariable analysis. The median PFS1 for first-line HDRT was 4.1 months, and the median PFS2 was 3.9 months. Rates of LF were 10.3% at 12 months and 11.7% at 24 months. The incidence of SCST following HDRT was 59.8% at 12 months and 76.1% at 24 months, with radiation targeted at the lung associated with a lower incidence of SCST.

Conclusion

HDRT for treating metastatic lesions in melanoma demonstrated excellent local control and may play a role in delaying SCST. Additional courses of HDRT may provide cumulative benefits.

Molecular landscape of prostate cancer bone metastasis

Prostate cancer (PC) has a high propensity to develop bone metastases, causing severe pain and pathological fractures that profoundly impact a patients' normal functions. Current clinical intervention is mainly palliative focused on pain management, and tumor progression is refractory to standard therapeutic regimens. This limited treatment efficacy is at least partially due to a lack of comprehensive understanding of the molecular landscape of the disease pathology, along with the intensive overlapping of physiological and pathological molecular signaling. The niche is overwhelmed with diverse cell types with inter- and intra-heterogeneity, along with growth factor-enriched cells that are supportive of invading cell proliferation, providing an additional layer of complexity. This review seeks to provide molecular insights into mechanisms underlying PC bone metastasis development and progression.

An Update on the Management of Bone Metastases

PURPOSE OF REVIEW

Increasing life expectancy among patients with advanced cancer has placed a greater emphasis on optimizing pain control and quality of life. Concurrently, significant advancements in radiotherapy for bone metastases have permitted for dose escalation strategies such as stereotactic radiotherapy. This review aims to provide updated information on the management of bone metastases in light of these developments.

RECENT FINDINGS

We reviewed recent studies regarding the role and details of external beam radiotherapy for bone metastases, with emphasis on differences by treatment site as well as intention (palliative versus ablative for oligometastases). Conventional palliative radiotherapy remains a mainstay of management. While stereotactic radiotherapy may augment durability of pain relief and even survival time, there are significant questions remaining regarding optimal dosing and patient selection. Radiotherapy for bone metastases continues to evolve, particularly with increasing use of stereotactic radiotherapy. Future studies are needed to clarify optimal dose, fractionation, modality, and patient selection criteria among different radiotherapy approaches.

Practice and principles of stereotactic body radiation therapy for spine and non-spine bone metastases

Radiotherapy is the dominant treatment modality for painful spine and non-spine bone metastases (NSBM). Historically, this was achieved with conventional low dose external beam radiotherapy, however, stereotactic body radiotherapy (SBRT) is increasingly applied for these indications. Meta-analyses and randomized clinical trials have demonstrated improved pain response and more durable tumor control with SBRT for spine metastases. However, in the setting of NSBM, there is limited evidence supporting global adoption and large scale randomized clinical trials are in need. SBRT is technically demanding requiring careful consideration of organ at risk tolerance, and strict adherence to technical requirements including immobilization, simulation, contouring and image-guidance procedures. Additional considerations include follow up practices after SBRT, with appropriate imaging playing a critical role in response assessment. Finally, there is renewed research into promising new technologies that may further refine the use of SBRT in both spinal and NSBM in the years to come.

Stereotactic Body and Conventional Radiotherapy for Painful Bone Metastases: A Systematic Review and Meta-Analysis

Importance

Conventional external beam radiotherapy (cEBRT) and stereotactic body radiotherapy (SBRT) are commonly used treatment options for relieving metastatic bone pain. The effectiveness of SBRT compared with cEBRT in pain relief has been a subject of debate, and conflicting results have been reported.

Objective

To compare the effectiveness associated with SBRT vs cEBRT for relieving metastatic bone pain.

Data Sources

A structured search was performed in the PubMed, Embase, and Cochrane databases on June 5, 2023. Additionally, results were added from a new randomized clinical trial (RCT) and additional unpublished data from an already published RCT.

Study Selection

Comparative studies reporting pain response after SBRT vs cEBRT in patients with painful bone metastases.

Data Extraction and Synthesis

Two independent reviewers extracted data from eligible studies. Data were extracted for the intention-to-treat (ITT) and per-protocol (PP) populations. The study is reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline.

Main Outcomes and Measures

Overall and complete pain response at 1, 3, and 6 months after radiotherapy, according to the study's definition. Relative risk ratios (RRs) with 95% CIs were calculated for each study. A random-effects model using a restricted maximum likelihood estimator was applied for meta-analysis.

Results

There were 18 studies with 1685 patients included in the systematic review and 8 RCTs with 1090 patients were included in the meta-analysis. In 7 RCTs, overall pain response was defined according to the International Consensus on Palliative Radiotherapy Endpoints in clinical trials (ICPRE). The complete pain response was reported in 6 RCTs, all defined according to the ICPRE. The ITT meta-analyses showed that the overall pain response rates did not differ between cEBRT and SBRT at 1 (RR, 1.14; 95% CI, 0.99-1.30), 3 (RR, 1.19; 95% CI, 0.96-1.47), or 6 (RR, 1.22; 95% CI, 0.96-1.54) months. However, SBRT was associated with a higher complete pain response at 1 (RR, 1.43; 95% CI, 1.02-2.01), 3 (RR, 1.80; 95% CI, 1.16-2.78), and 6 (RR, 2.47; 95% CI, 1.24-4.91) months after radiotherapy. The PP meta-analyses showed comparable results.

Conclusions and Relevance

In this systematic review and meta-analysis, patients with painful bone metastases experienced similar overall pain response after SBRT compared with cEBRT. More patients had complete pain alleviation after SBRT, suggesting that selected subgroups will benefit from SBRT.

Stereotactic body radiation therapy for bone oligometastases

Stereotactic body radiation therapy is effective for the local management of oligometastases (at most five metastases) with a benefit in survival and local control. Most studies on the management of oligometastases focus on all oligometastatic sites in primary cancer and very few focus on a single oligometastatic site. In particular, there are few data on bone oligometastases, which represent one of the preferred sites for secondary cancer locations. This article focuses on the benefit of stereotactic radiotherapy for bone oligometastases of all cancers by histological types, and reviews the results of major studies in this field.

Short-term pain control after palliative radiotherapy for uncomplicated bone metastases: a prospective cohort study

This study aimed at evaluating the efficacy of different radiotherapy (RT) fractionation regimens in managing uncomplicated painful bone metastases (BM) and identifying predictive factors for pain control. Patients with 1 to 4 symptomatic BM from any primary solid tumors and a life expectancy exceeding 3 months were included in the study and received palliative RT, with SBRT restricted in the context of oligometastatic disease or in patients with good prognosis. Pain analysis using the Brief Pain Inventory (BPI) tool was conducted at baseline, 1 and 3 months after RT. Analgesic intake was recorded as morphine-equivalent doses (OME). Pain response was assessed using the International Consensus on Palliative Radiotherapy Endpoint (ICPRE). Multivariate logistic regression analyzed patient-related, tumor-related, and treatment-related factors predicting BM pain control at 3 months post-RT. From Feb 2022 to Feb 2023, 44 patients with 65 symptomatic BM were investigated. Breast (32%) and lung (24%) tumors were the most common primary tumors. Treatment plans included 3DCRT (60%) and VMAT (40%), with a median biological effective dose for tumors (BED) of 29 Gy [14-108]. All patients completed the 3-month follow-up. Pain response rates were 62% at 1 month and 60% at 3 months. Responders had better PS ECOG scores (67%; P = 0.008) and received active systemic therapies (67%: P = 0.036). Non-responders had lower pretreatment BPI (mean: 13.7 vs. 58.2; P = 0.032), with significantly higher values after 1 month (mean: 9.1 vs. 5.3, P = 0.033). Baseline BPI (OR: 1.17; 95% CI: 1.032-1.327; P = 0.014) and BPI at 1 month (OR: 0.83; 95% CI: 0.698-0.976; P = 0.025) were independent predictors of pain response at 3 months. Our findings show that palliative RT ensured short-term pain control in patients with BM, regardless of tumor type and dose-fractionation regimen. A larger sample size and a longer follow-up could potentially identify which patients are likely to benefit most from RT, and which fractionation might be indicated for achieving a durable pain relief. A multidisciplinary approach is paramount to provide a better care to BM patients.

Dosimetric impact of CT metal artifact reduction for spinal implants in stereotactic body radiotherapy planning

Background

Metal artifacts due to spinal implants may affect the accuracy of dose calculation for radiotherapy. However, the dosimetric impact of metal artifact reduction (MAR) for spinal implants in stereotactic body radiotherapy (SBRT) plans has not been well studied. The objective of this study was to evaluate the dosimetric impact of MAR in spinal SBRT planning with three clinically common dose calculation algorithms.

Methods

Gammex phantom and 10 patients' computed tomography (CT) images were studied to investigate the effects of titanium implants. A commercial orthopedic MAR algorithm was employed to reduce artifacts. Dose calculations for SBRT were conducted on both artifact-corrected and uncorrected images using three commercial algorithms [analytical anisotropic algorithm (AAA), Acuros XB (AXB), and Monte Carlo (MC)]. Dose discrepancies between artifact-corrected and uncorrected cases were appraised using a dose-volume histogram (DVH) and 3-dimensional (3D) gamma analysis with different distance to agreement (DTA) and dose difference criteria. The gamma agreement index (GAI) was denoted as G(∆D, DTA). Statistical analysis of t-test was utilized to evaluate the dose differences of different algorithms.

Results

The phantom study demonstrated that titanium metal artifacts can be effectively reduced. The patient cases study showed that dose differences between the artifact-corrected and uncorrected datasets were small evaluated by gamma index and DVH. Gamma analysis found that even the strict criterion local G(1,1) had average values ≥93.9% for the three algorithms. For all DVH metrics, average differences did not exceed 0.7% in planning target volume (PTV) and 2.1% in planning risk volume of spinal cord (PRV-SC). Statistical analysis showed that the observed dose differences of MC method were significantly larger than those of AAA (P<0.01 for D98% of PTV and P<0.001 for D0.1cc of spinal cord) and AXB methods (P<0.001 for D98% and P<0.0001 for D0.1cc).

Conclusions

Dosimetric impact of artifacts caused by titanium implants is not significant in spinal SBRT planning, which indicates that dose calculation algorithms might not be very sensitive to CT number variation caused by titanium inserts.

Factors Associated with Long-Term Prostate Cancer Survival after Palliative Radiotherapy to a Bone Metastasis and Contemporary Palliative Systemic Therapy: A Retrospective, Population-Based Study

BACKGROUND

Radiation therapy (RT) is an established palliative treatment for bone metastases; however, little is known about post-radiation survival and factors which impact it. The aim of this study was to assess a population-based sample of metastatic prostate cancer patients receiving palliative radiation therapy to bone metastases and contemporary palliative systemic therapy and identify factors that impact long-term survival.

MATERIALS/METHODS

This retrospective, population-based, cohort study assessed all prostate cancer patients receiving palliative RT for bone metastases at a Canadian provincial Cancer program during a contemporary time period. Baseline patient, disease, and treatment characteristics were extracted from the provincial medical physics databases and the electronic medical record. Post-RT Survival intervals were defined as the time interval from the first fraction of palliative RT to death from any cause or date of the last known follow-up. The median survival of the cohort was used to dichotomize the cohort into short- and long-term survivors following RT. Univariable and multivariable hazard regression analyses were performed to identify variables associated with post-RT survival.

RESULTS

From 1 January 2018 until 31 December 2019, 545 palliative RT courses for bone metastases were delivered to n = 274 metastatic prostate cancer patients with a median age of 76 yrs (Interquartile range (IQR) 39-83) and a median follow-up of 10.6 months (range 0.2 to 47.9). The median survival of the cohort was 10.6 months (IQR 3.5-25 months). The ECOG performance status of the whole cohort was ≤2 in n = 200 (73%) and 3-4 in n = 67 (24.5%). The most commonly treated sites of bone metastasis were the pelvis and lower extremities n = 130 (47.4%), skull and spine n = 114 (41.6%), and chest and upper extremities n = 30 (10.9%). Most patients had CHAARTED high volume disease n = 239 (87.2%). On multivariable hazard regression analysis, an ECOG performance status of 3-4 (p = 0.02), CHAARTED high volume disease burden (p = 0.023), and non-receipt of systemic therapy (p = 0.006) were significantly associated with worse post-RT survival.

CONCLUSION

Amongst metastatic prostate cancer patients treated with palliative radiotherapy to bone metastases and modern palliative systemic therapies, ECOG performance status, CHAARTED metastatic disease burden, and type of first-line palliative systemic therapy were significantly associated with post-RT survival durations.

Incidence, survival comparison, and novel prognostic evaluation approaches for stage iii-iv pulmonary large cell neuroendocrine carcinoma and small cell lung cancer

BACKGROUND

Pulmonary large cell neuroendocrine carcinoma (LCNEC) and small cell lung cancer (SCLC) are two types of high-grade neuroendocrine carcinomas of the lung with poor prognosis. LCNEC has not been thoroughly studied due to its rarity, data are also lacking regarding the survival comparison and prognosis analysis of patients with locally advanced or metastatic LCNEC and SCLC.

METHODS

Data of patients with LCNEC, SCLC, and other NSCLC who were diagnosed from 1975 to 2019 were extracted from the Surveillance, Epidemiology and End Results (SEER) database to estimate incidence. Those in stage III-IV and being diagnosed from 2010 to 2015 were utilized further to investigate their clinical characteristics and prognosis. Propensity score matching (PSM) analyses at a ratio of 1:2 was used to compare their survival outcomes. Nomograms of LCNEC and SCLC were established with internal validation, and the nomogram of SCLC was externally validated by 349 patients diagnosed in Cancer hospital, Chinese Academy of Medical Sciences & Peking Union Medical College from January 1, 2012 to December 31, 2018.

RESULTS

The incidence of LCNEC has been increasing in recent decades, meanwhile that of SCLC and other types of NSCLC were decreasing. A total of 91,635 lung cancer patients, including 785 with LCNEC, 15,776 with SCLC, and 75,074 with other NSCLC were enrolled for further analysis. The survival of stage III-IV LCNEC resembles that of SCLC, and significantly worse than other types of NSCLC before and after PSM analysis. In pretreatment prognostic analysis, age, T stage, N stage, M stage, bone metastasis, liver metastasis, and brain metastasis were found to be associated with the survival of both LCNEC and SCLC, besides sex, bilaterality, and lung metastasis were additional prognostic factors for SCLC. Two nomograms and convenient online tools respectively for LCNEC and SCLC were established accordingly with favorable predicting accuracy of < 1-year, < 2-year, < 3-year survival probabilities. In external validation of the SCLC nomogram with a Chinese cohort, the AUCs of 1-year, 2-year and 3-year ROC were 0.652, 0.669, and 0.750, respectively. All the results of 1-, 2-, 3- year variable-dependent ROC curves verified the superior prognostic value of our nomograms for LCNEC and SCLC over the traditional T/N/M staging system.

CONCLUSIONS

Based on large sample-based cohort, we compared the epidemiological trends and survival outcomes between locally advanced or metastatic LCNEC, SCLC, and other NSCLC. Furthermore, two prognostic evaluation approaches respectively for LCNEC and SCLC might present as practical tools for clinicians to predict the survival outcome of these patients and facilitate risk stratification.

Stereotactic Body Radiation Therapy Versus Conventional Radiation Therapy in Pain Relief for Bone Metastases: A Systematic Review and Meta-Analysis

PURPOSE

This study aimed to investigate the difference in pain relief between stereotactic body radiation therapy (SBRT) and conventional radiation therapy (cRT) for patients with bone metastases.

METHODS AND MATERIALS

Clinical trials and observational studies comparing SBRT versus cRT for bone metastases were retrieved. The main endpoint was pain relief after radiation therapy; the secondary endpoints were pain score change, local progression-free survival, reirradiation rate, and toxic events. When there was a significant heterogeneity, the random-effects model was applied. Otherwise, the fixed-effects model was used. Analyses of all included studies were performed first, followed by analyses of randomized controlled trials (RCTs) only.

RESULTS

Six RCTs, 1 prospective cohort study, and 3 retrospective observational studies were enrolled. Between 2004 and 2019, 448 patients received SBRT, and 445 patients received cRT. All prospective studies defined the lesions as oligometastatic. Pooled results based on all included studies indicated that SBRT was generally associated with a higher overall relief rate (P < .001 at 3 months; P = .015 at 6 months) and complete relief rate (P = .029 at 1 month; P < .001 at 6 months). Pooled results based on RCTs indicated that at 3 and 6 months, SBRT was associated with a higher overall relief rate (P < .001 and P = .017, respectively) and complete relief rate (P < .001 and P < .00, respectively). Subgroup analyses indicated that in more cases, the analgesic advantage of SBRT was more obvious when spinal lesions were irradiated, when the difference in the mean biological effective dose (BED) was less, or when intensity modulated radiation therapy was used to deliver SBRT.

CONCLUSIONS

Excessive elevation of BED introduces the risk of diminishing the analgesic effect of SBRT. SBRT delivered using intensity modulated radiation therapy is preferred for pain relief in spinal oligometastases. More RCTs are required to determine the most appropriate BED or dose regimen for SBRT.

Systematic Review of Tumor Segmentation Strategies for Bone Metastases

Purpose: To investigate the segmentation approaches for bone metastases in differentiating benign from malignant bone lesions and characterizing malignant bone lesions. Method: The literature search was conducted in Scopus, PubMed, IEEE and MedLine, and Web of Science electronic databases following the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A total of 77 original articles, 24 review articles, and 1 comparison paper published between January 2010 and March 2022 were included in the review. Results: The results showed that most studies used neural network-based approaches (58.44%) and CT-based imaging (50.65%) out of 77 original articles. However, the review highlights the lack of a gold standard for tumor boundaries and the need for manual correction of the segmentation output, which largely explains the absence of clinical translation studies. Moreover, only 19 studies (24.67%) specifically mentioned the feasibility of their proposed methods for use in clinical practice. Conclusion: Development of tumor segmentation techniques that combine anatomical information and metabolic activities is encouraging despite not having an optimal tumor segmentation method for all applications or can compensate for all the difficulties built into data limitations.

Percent of remaining life on palliative radiation treatment: solely a function of fractionation?

Background

This study analyzed the percent of remaining life (PRL) on treatment in patients irradiated for bone metastases. Bone metastases were treated together with other target volumes, if indicated, e.g. a 10-fraction treatment course that included brain and bone metastases. PRL was determined by calculating the time between start and finish of palliative radiotherapy (minimum 1 day in case of a single-fraction regimen) and dividing it by overall survival in days from start of radiotherapy.

Materials and methods

Different baseline parameters were assessed for association with dichotomized PRL (< 5% vs. ≥ 5%). The retrospective study included 219 patients (287 courses of palliative radiotherapy). After univariate analyses, multi-nominal logistic regression was employed.

Results

PRL on treatment ranged from 1-23%. Single-fraction radiotherapy resulted in < 5% PRL on treatment in all cases. All courses with 10 fractions resulted in at least 5% PRL on treatment. Significant associations were found between various baseline parameters and PRL category. With fractionation included in the regression model, 3 parameters retained significant p-values: Karnofsky performance status (KPS), none-bone target volume and fractionation (all with p < 0.001). If analyzed without fractionation, none-bone target volume (p < 0.001), hemoglobin (p < 0.001), KPS (p = 0.01), lack of additional systemic treatment (p = 0.01), and hypercalcemia (p = 0.04) were significant.

Conclusions

Fractionation is an easily modifiable factor with high impact on PRL. Patients with KPS < 70 and those treated for additional target types during the same course are at high risk of spending a larger proportion of their remaining life on treatment.

Bias due to statistical handling of death and reirradiation in the assessment of duration of response after palliative radiotherapy: a scoping review and analysis of clinical data

OBJECTIVES

We investigated the influence of handling death and reirradiation on the estimation of duration of response (DOR).

METHODS

First, we performed a scoping review on methods to assess DOR in palliative radiotherapy. Second, we performed three different analyses on a subgroup of patients from a previously published prospective study. The first analysis was a competing risks analysis considering relapse of pain as the event of interest and death and reirradiation as competing events (Analysis A). The second and third analyses were standard survival analyses where the event of interest was a composite outcome of relapse of pain, death, or reirradiation (Analysis B) and relapse of pain (Analysis C), respectively.

RESULTS

Death was considered as an event of interest in less than half of the papers, while reirradiation was not considered in any of the studies. Competing risks analysis was not performed in any of the studies. In the analysis of clinical data, competing risks analysis showed that relapse of pain predominated as the cause of the end of response. Median DOR was correctly estimated to be 4.1 months in Analyses A and B, but was overestimated to be 8.1 months in Analysis C.

CONCLUSIONS

Death and reirradiation should be treated as the events of interest that mark the end of response (as in Analyses A and B) to avoid overestimation of treatment efficacy and an invalid assumption of independent censoring.

ADVANCES IN KNOWLEDGE

The definition of end of response remains inconclusive in the assessment of DOR. We recommend competing risks analysis (Analysis A), by which we can estimate cumulative incidence of each event type and evaluate the necessity of reirradiation.

Dose-escalated radiotherapy with simultaneous integrated boost for bone metastases in selected patients with assumed favourable prognosis

BACKGROUND

Stereotactic body radiotherapy (SBRT) concepts for dose escalation are increasingly used for bone metastases in patients with oligometastatic or oligoprogressive disease. For metastases that are not suitable for SBRT-regimens, a treatment with 30/40 Gy with simultaneous integrated boost (SIB) in 10 fractions represents a possible regimen. The aim of this study was to investigate the feasibility of this concept and the acute and subacute toxicities.

PATIENTS AND METHODS

Clinical records for dose-escalated radiotherapy of all consecutive patients treated with this regimen were evaluated retrospectively (24 patients with 28 target volumes for oncologic outcomes and 25 patients with 29 target volumes for treatment feasibility and dose parameters analysis). Analysis of radiotherapy plans included size of target volumes and dosimetric parameter for target volumes and organs at risk (OAR). Acute and subacute toxicities were evaluated according to Common Terminology Criteria for Adverse Events (CTCAE) V4.0.

RESULTS

The most common localization was the spine (71.4%). The most common histology was prostate cancer (45.8%). Oligometastatic or oligoprogressive disease was the indication for dose-escalated radiotherapy in 19/24 patients (79.2%). Treatment was feasible with all patients completing radiotherapy. Acute toxicity grade 1 was documented in 36.0% of the patients. During follow up, one patient underwent surgery due to bone instability. The 1-year local control and patient-related progression-free survival (PFS) were 90.0 ± 6.7% and 33.3 ± 11.6%, respectively.

CONCLUSIONS

Dose-escalated hypofractionated radiotherapy with simultaneous integrated boost for bone metastases resulted in good local control with limited acute toxicities. Only one patient required surgical intervention. The regimen represents an alternative to SBRT in selected patients.

A Nanomedicine Structure-Activity Framework for Research, Development, and Regulation of Future Cancer Therapies

Despite their clinical success in drug delivery applications, the potential of theranostic nanomedicines is hampered by mechanistic uncertainty and a lack of science-informed regulatory guidance. Both the therapeutic efficacy and the toxicity of nanoformulations are tightly controlled by the complex interplay of the nanoparticle's physicochemical properties and the individual patient/tumor biology; however, it can be difficult to correlate such information with observed outcomes. Additionally, as nanomedicine research attempts to gradually move away from large-scale animal testing, the need for computer-assisted solutions for evaluation will increase. Such models will depend on a clear understanding of structure-activity relationships. This review provides a comprehensive overview of the field of cancer nanomedicine and provides a knowledge framework and foundational interaction maps that can facilitate future research, assessments, and regulation. By forming three complementary maps profiling nanobio interactions and pathways at different levels of biological complexity, a clear picture of a nanoparticle's journey through the body and the therapeutic and adverse consequences of each potential interaction are presented.

Bone-only oligometastatic renal cell carcinoma patients treated with stereotactic body radiotherapy: a multi-institutional study

PURPOSE

This study aimed to analyze the prognostic factors associated with overall survival (OS) and progression-free survival (PFS) in patients with bone-only metastatic renal cell carcinoma (RCC) who have five or fewer lesions treated with stereotactic body radiotherapy (SBRT).

METHODS

The clinical data of 54 patients with 70 bone metastases undergoing SBRT treated between 2013 and 2020 with a dose of at least 5 Gy per fraction and a biologically effective dose (BED) of at least 90 Gy were retrospectively evaluated.

RESULTS

The majority of lesions were located in the spine (57.4%) and had only one metastasis (64.8%). After a median follow-up of 22.4 months, the 1‑ and 2‑year OS rates were 84.6% and 67.3%, respectively, and median OS was 43.1 months. The 1‑ and 2‑year PFS rates and median PFS were 63.0%, 38.9%, and 15.3 months, respectively. In SBRT-treated lesions, the 1‑year local control (LC) rate was 94.9%. Age, metastasis localization, and number of fractions of SBRT were significant prognostic factors for OS in univariate analysis. In multivariate analysis, patients with spinal metastasis had better OS compared to their counterparts, and patients who received single-fraction SBRT had better PFS than those who did not. No patient experienced acute or late toxicities of grade 3 or greater.

CONCLUSION

Despite excellent LC at the oligometastatic site treated with SBRT, disease progression was observed in nearly half of patients 13 months after metastasis-directed local therapy, particularly as distant disease progression other than the treated lesion, necessitating an effective systemic treatment to improve treatment outcomes.

Stereotactic Body Radiation Therapy versus Conventional External Beam Radiation Therapy for Painful Bone Metastases: A Systematic Review and Meta-analysis of Randomized Trials

PURPOSE

To compare the efficacy and safety of stereotactic body radiation therapy (SBRT) and conventional external beam radiation therapy (cEBRT) in patients with previously unirradiated painful bone metastases (BM).

METHODS

We searched biomedical databases for eligible randomized trials (RCTs). The outcomes of interest were pain response, local progression, overall survival (OS) and adverse events. We used established tools to assess the quality of the individual trials and certainty of the pooled evidence. We performed meta-analyses using random effects models.

RESULTS

Six RCTs were identified. SBRT improved complete pain response rates at 3 months (OR, 3.38; 95% CI, 1.88-6.07; high certainty), reduced local progression rates (OR, 0.19; 95% CI, 0.06-0.62; high certainty) and increase pain flare rates. There were no differences for other outcomes.

CONCLUSION

Among patients with previously unirradiated painful BM, SBRT significantly improved complete pain response rates at 3 months, delayed local progression and increase pain flare rates.

Stereotactic radiosurgery for bone metastases in oligometastatic prostate cancer patients: DESTROY-2 clinical trial subanalysis

INTRODUCTION

Aim of this analysis was to report toxicity and clinical outcomes in oligorecurrent prostate cancer (PCa) patients treated with single fraction stereotactic radiosurgery (SRS) for bone metastases.

METHODS

We separately analyzed clinical data of PCa patients with bone oligometastases enrolled in a prospective phase I trial (DESTROY-2). DESTROY-2 was based on SRS delivered using volumetric modulated arc therapy in patients with primary or metastatic tumors in several extra-cranial body sites. Acute and late toxicity, biochemical tumor response, local control (LC), distant metastases-free (DPFS), progression-free (PFS), time to next-line systemic treatment-free (NEST-FS), and overall survival (OS) were calculated.

RESULTS

Data on 37 PCa patients, carrying out 50 bone metastases, candidates for curative-intent treatment and treated with SRS at our Institution were collected. SRS dose ranged between 12 and 24 Gy. One grade 1 acute skin toxicity in one patient treated on the hip (24 Gy) and one grade 1 late skin toxicity in a patient with a scapular lesion (24 Gy) were recorded. No cases of bone fracture were registered in the treated population. With a median follow-up of 25 months (range 3-72 months) 2-year actuarial LC, DPFS, PFS, and OS were 96.7%, 58.1%, 58.1%, and 95.8%, respectively. Median and 2-year NEST-FS were 30 months (range 1-69 months) and 51.2%, respectively.

CONCLUSIONS

Data analysis showed few toxicity events, high local control rate and prolonged NEST-FS after linear accelerator-based radiosurgery of bone oligometastases from PCa. The possibility of postponing systemic treatments in patients with oligometastatic PCa by means of SRS should be taken into account. Further prospective studies on larger series are needed to confirm the reported results.

ESTRO ACROP guidelines for external beam radiotherapy of patients with uncomplicated bone metastases

After liver and lungs, bone is the third most common metastatic site (Nystrom et al., 1977). Almost all malignancies can metastasize to the skeleton but 80% of bone metastases originate from breast, prostate, lung, kidney and thyroid cancer (Mundy, 2002). Introduction of effective systemic treatment in many cancers has prolonged patients' survival, including those with bone metastases. Bone metastases may significantly reduce quality of life due to related symptoms and possible complications, such as pain and neurologic compromise. The most serious complications of bone metastases are skeletal-related events (SRE), defined as pathologic fracture, spinal cord compression, pain, or other symptoms requiring an urgent intervention such as surgery or radiotherapy. In turn, growing access to modern diagnostic tools allows early detection of asymptomatic bone metastases that could be successfully managed with local treatment avoiding development of SRE. The treatment for bone metastases should focus on relieving existing symptoms and preventing new ones. Radiotherapy is the standard of care for patients with symptomatic bone metastases, providing durable pain relief with minimal toxicity and reasonable cost-effectiveness. Historically, the dose was prescribed in one to five fractions and delivered using simple planning techniques. While 3D-conformal radiotherapy is still widely used for treating bone metastases, introduction of highlyconformal radiotherapy techniques such as stereotactic body radiotherapy (SBRT) have opened new therapeutic possibilities that should be considered in selected patients with bone metastases.

Stereotactic radiotherapy for bone oligometastases

About 60–90% of cancer patients are estimated to develop bone metastases, particularly in the spine.

Bone scintigraphy, computed tomography (CT ) and magnetic resonance imaging (MRI ) are currently used to assess metastatic bone disease; positron emission tomography/computed tomography (PET-CT ) has become more widespread in clinical practice because of its high sensitivity and specificity with about 95% diagnostic accuracy. The most common and well-known radiotracer is 18F-fluorodeoxyglucose (¹⁸FDG); several other PET-radiotracers are currently under investigation for different solid tumors, such as ¹¹C or ¹⁸FDG-choline and prostate specific membrane antigen (PSMA)-PET/CT for prostate cancer. In treatment planning, standard and investigational imaging modalities should be registered with the planning CT so as to best define the bone target volume. For target volume delineation of spine metastases, the International Spine Radiosurgery Consortium (ISRC ) of North American experts provided consensus guidelines. Single fraction stereotactic radiotherapy (SRT ) doses ranged from 12 to 24 Gy; fractionated SRT administered 21–27 Gy in 3 fractions or 20–35 Gy in 5 fractions. After spine SRT, less than 5% of patients experienced grade ≥ 3 acute toxicity. Late toxicity included the extremely rare radiation-induced myelopathy and a 14% risk of de novo vertebral compression fractures.

Predictive factors, preventive implications, and personalized surgical strategies for bone metastasis from lung cancer: population-based approach with a comprehensive cancer center-based study

Background

Bone metastasis (BM) and skeletal-related events (SREs) happen to advanced lung cancer (LC) patients without warning. LC-BM patients are often passive to BM diagnosis and surgical treatment. It is necessary to guide the diagnosis and treatment paradigm for LC-BM patients from reactive medicine toward predictive, preventive, and personalized medicine (PPPM) step by step.

Methods

Two independent study cohorts including LC-BM patients were analyzed, including the Surveillance, Epidemiology, and End Results (SEER) cohort (n = 203942) and the prospective Fudan University Shanghai Cancer Center (FUSCC) cohort (n = 59). The epidemiological trends of BM in LC patients were depicted. Risk factors for BM were identified using a multivariable logistic regression model. An individualized nomogram was developed for BM risk stratification. Personalized surgical strategies and perioperative care were described for FUSCC cohort.

Results

The BM incidence rate in LC patients grew (from 17.53% in 2010 to 19.05% in 2016). Liver metastasis was a significant risk factor for BM (OR = 4.53, 95% CI = 4.38-4.69) and poor prognosis (HR = 1.29, 95% CI = 1.25-1.32). The individualized nomogram exhibited good predictive performance for BM risk stratification (AUC = 0.784, 95%CI = 0.781-0.786). Younger patients, males, patients with high invasive LC, and patients with other distant site metastases should be prioritized for BM prevention. Spine is the most common site of BM, causing back pain (91.5%), pathological vertebral fracture (27.1%), and difficult walking (25.4%). Spinal surgery with personalized spinal reconstruction significantly relieved pain and improved daily activities. Perioperative inflammation, immune, and nutrition abnormities warrant personalized managements. Radiotherapy needs to be recommended for specific postoperative individuals.

Conclusions

The presence of liver metastasis is a strong predictor of LC-BM. It is recommended to take proactive measures to prevent BM and its SREs, particularly in young patients, males, high invasive LC, and LC with liver metastasis. BM surgery and perioperative management are personalized and required. In addition, adjuvant radiation following separation surgery must also be included in PPPM-guided management.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-022-00270-9.

Prognostic Factors Influencing Survival and a Treatment Pattern Analysis of Conventional Palliative Radiotherapy for Patients with Bone Metastases

BACKGROUND

Treatment indication for bone metastases is influenced by patient prognosis. Single-fraction radiotherapy (SFRT) was proven equally effective as multiple fractionation regimens (MFRT) but continues to be underused.

OBJECTIVE

Primary objectives: (a) to identify prognostic factors for overall survival and (b) to analyze treatment patterns of palliative radiotherapy (proportion of SFRT indication and predictive factors of radiotherapy regimen) for bone metastases.

METHODS

582 patients with bone metastases who underwent conventional radiotherapy between January 1st 2014-31 December 2017 were analyzed. The Cox proportional hazard model was used to identify predictors of overall survival. For the treatment pattern analysis, 677 radiotherapy courses were evaluated. The logistic regression model was used to identify potential predictors of radiotherapy regimen.

RESULTS

The 3-year overall survival was 15%. Prognostic factors associated with poor overall survival were multiple bone metastases [hazard ratio (HR = 5.4)], poor performance status (HR = 1.5) and brain metastases (HR = 1.37). SFRT prescription increased from 41% in 2017 to 51% in 2017. Predictors of SFRT prescription were a poor performance status [odds ratio (OR = 0.55)], lung (OR = 0.49) and urologic primaries (OR = 0.33) and the half-body lower site of irradiation (OR = 0.59). Spinal metastases were more likely to receive MFRT (OR = 2.09).

CONCLUSIONS

Based on the prognostic factors we identified, a selection protocol for patients candidates for palliative radiotherapy to bone metastases could be established, in order to further increase SFRT prescription in our institution.

International Multi-institutional Patterns of Contouring Practice and Clinical Target Volume Recommendations for Stereotactic Body Radiation Therapy for Non-Spine Bone Metastases

PURPOSE

Despite the increasing use of stereotactic body radiation therapy for non-spine bone metastases (NSBM), there is no established standard for target delineation. The objective of this study was to provide consensus recommendations on clinical target volume (CTV) delineation based on international expert contours.

METHODS AND MATERIALS

Eleven cases of NSBM were contoured by 9 international radiation oncologists. For each case, the gross tumor volume was provided on the simulation computed tomography scans with accompanying magnetic resonance imaging. Participants contoured the CTV and completed a clinical survey. Agreement between CTV contours were analyzed with simultaneous truth and performance level estimation using the kappa coefficient and the Dice similarity coefficient (DSC) and summarized to establish contouring recommendations. A direction-dependent analysis was applied to the consensus contours to quantify margins.

RESULTS

All CTV contours were completed. Six participants used a single-dose level, whereas 3 used a 2-dose level simultaneous integrated boost (SIB) technique. For the SIB cases, the largest volume receiving a stereotactic body radiation therapy (SBRT) dose was used for contour analysis. There was substantial agreement between contours across cases with a mean kappa of 0.72 (mean sensitivity 0.85, mean specificity 0.97). The mean DSC value was 0.77 (range, 0.67-0.87). Consensus CTV contouring recommendations were (1) an intraosseous CTV margin of 5 to 10 mm should be strongly considered within contiguous bone; (2) an extraosseous margin of 5 to 10 mm should be strongly considered where there is soft tissue disease or cortical bone disruption; (3) CTVs should be manually cropped to respect anatomic barriers to spread (eg, peritoneal cavity, pleura, uninvolved joint space and cortical bone).

CONCLUSIONS

CTV contouring recommendations for NSBM-SBRT were established based on analysis of international expert consensus contours with a high level of agreement. These principles may provide guidance to treating physicians and inform future study until prospective clinical data can provide further refinement.

An international pooled analysis of SBRT outcomes to oligometastatic spine and non-spine bone metastases

PURPOSE

There is a paucity of data on SBRT to non-spine bone (NSB) lesions compared to spine metastases. We report local recurrence (LR), widespread progression (WSP), and overall survival (OS) for oligometastatic patients treated to bone lesions with SBRT and investigate the hypothesis that outcomes are different between patients with spine and non-spine bone oligometastatic disease.

METHODS

Patients with oligometastatic disease (≤5 cumulative extracranial metastases) treated with bone SBRT at 6 international institutions from 2007 to 2016 were reviewed. Fine and Gray competing risks and Cox regressions were used to analyze univariable and multivariable relationships between disease/treatment factors and outcomes.

RESULTS

In total, 288 spine and 233 NSB lesions are reported in 356 patients. Cumulative incidence of LR across all bone lesions was 6.3%, 12.6% and 19.3% at 6 mo, 1 yr and 2 yrs. While univariable analysis suggested inferior LC and OS in spine patients, this did not hold true in multivariable analysis. The final regression model for LR in NSB lesions included PTV ≥ median of 31.8 cc (HR 5.02, p = 0.014) and primary histology, with RCC and NSCLC conferring a 10.8- and 6.5-fold increased risk of LR compared to prostate histology, respectively. The spine LR model included radioresistant histology (HR 2.11, p = 0.0051), PTV Dmin (BED10) ≥ median of 19.1 Gy (HR 0.46, p = 0.0085), and epidural disease (HR 1.99, p = 0.016).

CONCLUSION

This large multi-institutional series reports comparably excellent response to SBRT for a balanced distribution of oligometastatic NSB and spine lesions. Dose escalation for large and/or radioresistant NSB lesions should be explored, given the typical lack of an immediately adjacent dose-limiting critical structure.

Advances in radiotherapy in bone metastases in the context of new target therapies and ablative alternatives: A critical review

In patients with bone metastases (BM), radiotherapy (RT) is used to alleviate symptoms, reduce the risk of fracture, and improve quality of life (QoL). However, with the emergence of concepts like oligometastases, minimal invasive surgery, ablative therapies such as stereotactic ablative RT (SABR), radiosurgery (SRS), thermal ablation, and new systemic anticancer therapies, there have been a paradigm shift in the multidisciplinary approach to BM with the aim of preserving mobility and function survival. Despite guidelines on using single-dose RT in uncomplicated BM, its use remains relatively low. In uncomplicated BM, single-fraction RT produces similar overall and complete response rates to RT with multiple fractions, although it is associated with a higher retreatment rate of 20% versus 8%. Complicated BM can be characterised as the presence of impending or existing pathologic fracture, a major soft tissue component, existing spinal cord or cauda equina compression and neuropathic pain. The rate of complicated BM is around 35%. Unfortunately, there is a lack of prospective trials on RT in complicated BM and the best dose/fractionation regimen is not yet established. There are contradictory outcomes in studies reporting BM pain control rates and time to pain reduction when comparing SABR with Conventional RT. While some studies showed that SABR produces a faster reduction in pain and higher pain control rates than conventional RT, other studies did not show differences. Moreover, the local control rate for BM treated with SABR is higher than 80% in most studies, and the rate of grade 3 or 4 toxicity is very low. The use of SABR may be preferred in three circumstances: reirradiation, oligometastatic disease, and radioresistant tumours. Local ablative therapies like SABR can delay change or use of systemic therapy, preserve patients' Qol, and improve disease-free survival, progression-free survival and overall survival. Moreover, despite the potential benefit of SABR in oligometastatic disease, there is a need to establish the optial indication, RT dose fractionation, prognostic factors and optimal timing in combination with systemic therapies for SABR. This review evaluates the role of RT in BM considering these recent treatment advances. We consider the definition of complicated BM, use of single and multiple fractions RT for both complicated and uncomplicated BM, reirradiation, new treatment paradigms including local ablative treatments, oligometastatic disease, systemic therapy, physical activity and rehabilitation.

Creation of clinical algorithms for decision-making in oncology: an example with dose prescription in radiation oncology

In oncology, decision-making in individual situations is often very complex. To deal with such complexity, people tend to reduce it by relying on their initial intuition. The downside of this intuitive, subjective way of decision-making is that it is prone to cognitive and emotional biases such as overestimating the quality of its judgements or being influenced by one’s current mood. Hence, clinical predictions based on intuition often turn out to be wrong and to be outperformed by statistical predictions. Structuring and objectivizing oncological decision-making may thus overcome some of these issues and have advantages such as avoidance of unwarranted clinical practice variance or error-prevention. Even for uncertain situations with limited medical evidence available or controversies about the best treatment option, structured decision-making approaches like clinical algorithms could outperform intuitive decision-making. However, the idea of such algorithms is not to prescribe the clinician which decision to make nor to abolish medical judgement, but to support physicians in making decisions in a systematic and structured manner. An example for a use-case scenario where such an approach may be feasible is the selection of treatment dose in radiation oncology. In this paper, we will describe how a clinical algorithm for selection of a fractionation scheme for palliative irradiation of bone metastases can be created. We explain which steps in the creation process of a clinical algorithm for supporting decision-making need to be  performed and which challenges and limitations have to be considered.

Outcomes of extra-cranial stereotactic body radiotherapy for metastatic breast cancer: Treatment indication matters

BACKGROUND AND PURPOSE

To summarize the clinical outcomes of stereotactic body radiotherapy (SBRT) for metastatic breast cancer (mBC) from a large institution.

MATERIALS AND METHODS

Patients with mBC who received extra-cranial SBRT to metastatic lesions from 2011 to 2017 were identified. Treatment indications were: oligometastases, oligoprogression, and local control of dominant tumor (CDT). Endpoints included overall survival (OS), progression-free survival (PFS), local control (LC) and cumulative incidence of starting/changing chemo or hormonal therapy (SCT). Univariate and multivariate analyses were used to identify predictive factors.

RESULTS

We analyzed 120 patients (193 treated metastatic lesions) with a median follow up of 15.25 months. 1-and 2-year LC rates were 89% and 86.6%, respectively. 1-and 2-year OS rates were 83.5% and 70%, respectively, with treatment indication and molecular subtype being the predictive factors on MVA. 1-year OS was 91.0%, 78.5% and 63.9% for oligometastases, oligoprogression and CDT, respectively (p = 0.003). The worst OS was seen in basal subtype with 1-and 2-year OS rates of 59.2% and 39.5% (p = 0.01). Treatment indication was found to be predictive for PFS and lower rates of SCT on MVA. 1-and 2-year PFS rates were 45% and 32%, respectively. The 1-year PFS for oligometastases, oligoprogression, and CDT was 66%, 19.6%, and 14.3%, respectively (p < 0.001). The cumulative incidence of SCT at 1-year was 12% for oligometastases, 39.7% for oligoprogression and 53.3% for CDT (p < 0.001).

CONCLUSION

Patients treated for oligometastases have better OS and PFS than those treated for oligoprogression or CDT. SBRT may delay SCT in mBC patients, particularly those with oligometastases. SBRT provided an excellent LC in mBC patients.

Miniaturized scintillator dosimeter for small field radiation therapy

The concept of a miniaturized inorganic scintillator detector is demonstrated in the analysis of the small static photon fields used in external radiation therapy. Such a detector is constituted by a 0.25 mm diameter and 0.48 mm long inorganic scintillating cell (1.6 × 10^-5cm³detection volume) efficiently coupled to a narrow 125μm diameter silica optical fiber using a tiny photonic interface (an optical antenna). The response of our miniaturized scintillator detector (MSD) under 6 MV bremsstrahlung beam of various sizes (from 1 × 1 cm²to 4 × 4 cm²) is compared to that of two high resolution reference probes, namely, a micro-diamond detector and a dedicated silicon diode. The spurious Cerenkov signal transmitted through our bare detector is rejected with a basic spectral filtering. The MSD shows a linear response regarding the dose, a repeatability within 0.1% and a radial directional dependence of 0.36% (standard deviations). Beam profiling at 5 cm depth with the MSD and the micro-diamond detector shows a mismatch in the measurement of the full widths at 80% and 50% of the maximum which does not exceed 0.25 mm. The same difference range is found between the micro-diamond detector and a silicon diode. The deviation of the percentage depth dose between the MSD and micro-diamond detector remains below 2.3% within the first fifteen centimeters of the decay region for field sizes of 1 × 1 cm², 2 × 2 cm²and 3 × 3 cm²(0.76% between the silicon diode and the micro-diamond in the same field range). The 2D dose mapping of a 0.6 × 0.6 cm²photon field evidences the strong 3D character of the radiation-matter interaction in small photon field regime. From a beam-probe convolution theory, we predict that our probe overestimates the beam width by 0.06%, making our detector a right compromise between high resolution, compactness, flexibility and ease of use. The MSD overcomes problem of volume averaging, stem effects, and despite its water non-equivalence it is expected to minimize electron fluence perturbation due to its extreme compactness. Such a detector thus has the potential to become a valuable dose verification tool in small field radiation therapy, and by extension in Brachytherapy, FLASH-radiotherapy and microbeam radiation therapy.

Clinical and dosimetric risk factors for vertebral compression fracture after single-fraction stereotactic body radiation therapy for spine metastases

Objectives

This analysis was performed to evaluate the incidence of vertebral compression fracture (VCF) and determine the contributing factors for VCF in patients undergoing single-fraction stereotactic body radiotherapy (SBRT) for spinal bone metastases (SBM).

Methods

A retrospective review of medical records was conducted for patients undergoing SBRT for SBM at our institution between January 2010 and December 2018. Patients who had undergone neither pre-SBRT surgical excision nor post-SBRT prophylactic fixation were included. The effects of clinical and dosimetric parameters were analyzed with respect to VCF risk. The following dosimietric parameters of the planning target volume (PTV) were calculated: mean/minimum/maximum dose, radiation dose to 10-90% volume, and irradiated volume receiving more than 10-25 Gy (PTV_V_{10 - 25 Gy}).

Results

Among 163 patients (179 vertebrae), 21 (12.8%) experienced VCF. The 1-year and 2-year VCF rates were 12.1% and 13.2%, respectively. Among dosimetric parameters, PTV_V15 Gy was the most significant for VCF prediction. In a univariate analysis, breast or prostate primary, no vertebral body collapse, and PTV_V_{15 Gy} ≤42 cm³ were significantly associated with a lower incidence rate of VCF. In a multivariate analysis, PTV_V_{15 Gy} was the only significant factor for VCF risk. The 1-year VCF rate was 3.8% in patients with PTV_V_{15 Gy} ≤42 cm³, while it was 22.1% in those with PTV_V_{15 Gy} > 42 cm³ (p < 0.01).

Conclusions

SBRT-related VCF was found in 12% of patients in our institution. The PTV_V_{15 Gy} is a significant factor for VCF prediction.

Scrambler therapy for incident pain in bone metastases

Incident pain, described as pain induced by bone metastasis and produced by movement, can be devastating. The high doses of opioids needed to control such pain may sedate the patient and cause additional complications. Treatment of incident pain with pharmaceuticals has rarely been studied; only eight patients have been reported in the literature who did not receive additional opioids. We present the case of a 69 year old man with shoulder destruction due to bone metastases who was able to use his arm for normal activities without pain after three sessions of scrambler therapy, a noninvasive form of electrical neuromodulation that requires further study.

Stereotactic body radiation therapy for spinal metastases: a novel local control stratification by spinal region

OBJECTIVE

This study evaluated a large cohort of patients treated with stereotactic body radiation therapy for spinal metastases and investigated predictive factors for local control, local progression-free survival (LPFS), overall survival, and pain response between the different spinal regions.

METHODS

The study was undertaken via retrospective review at a single institution. Patients with a tumor metastatic to the spine were included, while patients with benign tumors or primary spinal cord cancers were excluded. Statistical analysis involved univariate analysis, Cox proportional hazards analysis, the Kaplan-Meier method, and machine learning techniques (decision-tree analysis).

RESULTS

A total of 165 patients with 190 distinct lesions met all inclusion criteria for the study. Lesions were distributed throughout the cervical (19%), thoracic (43%), lumbar (19%), and sacral (18%) spines. The most common treatment regimen was 24 Gy in 3 fractions (44%). Via the Kaplan-Meier method, the 24-month local control was 80%. Sacral spine lesions demonstrated decreased local control (p = 0.01) and LPFS (p < 0.005) compared with those of the thoracolumbar spine. The cervical spine cases had improved local control (p < 0.005) and LPFS (p < 0.005) compared with the sacral spine and trended toward improvement relative to the thoracolumbar spine. The 36-month local control rates for cervical, thoracolumbar, and sacral tumors were 86%, 73%, and 44%, respectively. Comparably, the 36-month LPFS rates for cervical, thoracolumbar, and sacral tumors were 85%, 67%, and 35%, respectively. A planning target volume (PTV) > 50 cm3 was also predictive of local failure (p = 0.04). Fewer cervical spine cases had disease with PTV > 50 cm3 than the thoracolumbar (p = 5.87 × 10-8) and sacral (p = 3.9 × 10-3) cases. Using decision-tree analysis, the highest-fidelity models for predicting pain-free status and local failure demonstrated the first splits as being cervical and sacral location, respectively.

CONCLUSIONS

This study presents a novel risk stratification for local failure and LPFS by spinal region. Patients with metastases to the sacral spine may have decreased local control due to increased PTV, especially with a PTV of > 50 cm3. Multidisciplinary care should be emphasized in these patients, and both surgical intervention and radiotherapy should be strongly considered.

Systematic review of stereotactic body radiotherapy for nodal metastases

The aim of this analysis was to assess the efficacy of stereotactic body radiotherapy (SBRT) in terms of local control (LC) and progression-free survival (PFS) in patients with lymph node metastases (NMs) from solid tumors. A systematic literature search from the earliest date to July 25th, 2019 was performed following PRISMA guidelines. Papers reporting LC and/or PFS of NMs using SBRT (< 10 fractions) were selected. The clinical outcomes rates were pooled by means of a random or fixed-effect model. Twenty-nine studies were eligible (969 patients: 938 (LC) and 698 (PFS)). LC and PFS results were reported in 28 and 18 papers, respectively. Heterogeneity was observed in terms of patient and treatment characteristics. Pooled 2-year LC reported in 11 studies was 79.3% (95%CI, 72.8%-85.7%) with substantial heterogeneity between studies (Q2 test: p = 0.0083; I2 = 57.9%), while pooled 2-year PFS reported in 8 studies was 35.9% (95%CI, 22.1%-49.7%) with very high heterogeneity between studies (Q2 test: p < 0.0001; I2 = 86.1%). Grade ≥ 3 and Grade 5 toxicity rates were 2.0% and 0.2%, respectively. SBRT of NMs seems to be safe and effective in terms of LC. However, due to the marked heterogeneity of the included series, prospective studies are required.

Pain Response After Stereotactic Body Radiation Therapy Versus Conventional Radiation Therapy in Patients With Bone Metastases-A Phase 2 Randomized Controlled Trial Within a Prospective Cohort

PURPOSE

Pain response after conventional external beam radiation therapy (cRT) in patients with painful bone metastases is observed in 60% to 70% of patients. The aim of the VERTICAL trial was to investigate whether stereotactic body radiation therapy (SBRT) improves pain response.

METHODS AND MATERIALS

This single-center, phase 2, randomized controlled trial was conducted within the PRESENT cohort, which consists of patients referred for radiation therapy of bone metastases to our tertiary center. Cohort participants with painful bone metastases who gave broad informed consent for randomization were randomly assigned to cRT or SBRT. Only patients in the intervention arm received information about the trial and were offered SBRT (1 × 18 Gy, 3 × 10 Gy, or 5 × 7 Gy), which they could accept or refuse. Patients who refused SBRT underwent standard cRT (1 × 8 Gy, 5 × 4 Gy, or 10 × 3 Gy). Patients in the control arm were not informed. Primary endpoint was pain response at 3 months after radiation therapy. Secondary outcomes were pain response at any point within 3 months, mean pain scores, and toxicity. Data were analyzed intention to treat (ITT) and per protocol (PP). This trial was registered with Clinicaltrials.gov, NCT02364115.

RESULTS

Between January 29, 2015, and March 20, 2019, 110 patients were randomized. ITT analysis included 44 patients in the cRT arm and 45 patients in the SBRT arm. In the intervention arm, 12 patients (27%) declined SBRT, and 7 patients (16%) were unable to complete the SBRT treatment. In ITT, 14 of 44 patients (32%; 95% confidence interval [CI], 18%-45%) in the control arm and 18 of 45 patients (40%; 95% CI, 26%-54%) in the SBRT arm reported a pain response at 3 months (P = .42). In PP, these proportions were 14 of 44 (32%; 95% CI, 18%-45%) and 12 of 23 patients (46%; 95% CI, 27%-66%), respectively (P = .55). In ITT, a pain response within 3 months was reported by 30 of 44 control patients (82%; 95% CI, 68%-90%) and 38 of 45 patients (84%; 95% CI, 71%-92%) in the SBRT arm (P = .12). In PP, these proportions were 36 of 44 (82%; 95% CI, 68%-90%) and 26 of 27 patients (96%; 95% CI; 81%-100%), respectively (P = .12). No grade 3 or 4 toxicity was observed in either arm.

CONCLUSIONS

SBRT did not significantly improve pain response in patients with painful bone metastases. One in 4 patients preferred to undergo cRT over SBRT, and 1 in 5 patients starting SBRT was unable to complete this treatment. Because of this selective dropout, which can be attributed to the character of the intervention, the trial was underpowered to detect the prespecified difference in pain response.

Mechanisms for Tuning Engineered Nanomaterials to Enhance Radiation Therapy of Cancer

Engineered nanomaterials that produce reactive oxygen species on exposure to X- and gamma-rays used in radiation therapy offer promise of novel cancer treatment strategies. Similar to photodynamic therapy but suitable for large and deep tumors, this new approach where nanomaterials acting as sensitizing agents are combined with clinical radiation can be effective at well-tolerated low radiation doses. Suitably engineered nanomaterials can enhance cancer radiotherapy by increasing the tumor selectivity and decreasing side effects. Additionally, the nanomaterial platform offers therapeutically valuable functionalities, including molecular targeting, drug/gene delivery, and adaptive responses to trigger drug release. The potential of such nanomaterials to be combined with radiotherapy is widely recognized. In order for further breakthroughs to be made, and to facilitate clinical translation, the applicable principles and fundamentals should be articulated. This review focuses on mechanisms underpinning rational nanomaterial design to enhance radiation therapy, the understanding of which will enable novel ways to optimize its therapeutic efficacy. A roadmap for designing nanomaterials with optimized anticancer performance is also shown and the potential clinical significance and future translation are discussed.

Trends in Radiation Therapy for Bone Metastases, 2015 to 2017: Choosing Wisely in the Era of Complex Radiation

PURPOSE

Guidelines recommend short-course (≤10 fractions) external-beam radiation therapy (EBRT) for bone metastases. Stereotactic body radiation therapy (SBRT) may also improve outcomes; however, routine use is not recommended outside clinical trials. We assessed national radiation therapy trends in complex techniques for bone metastases and associated expenditures.

METHODS AND MATERIALS

Using a claims-based Medicare data set covering 84% of beneficiaries, we assessed the relative proportion of all radiation episodes represented by bone metastases. We then evaluated use of short-course and long-course (>10 fractions) EBRT, intensity modulated radiation therapy (IMRT), and SBRT for bone metastases in hospital-affiliated outpatient (OPD) or freestanding (FREE) facilities. We assessed differences using χ²d or Wilcoxon rank sum tests for categorical and continuous variables, respectively. We identified associations with modality, fractionation, and expenditures using multivariable logistic/linear regression.

RESULTS

Among 467,781 radiation episodes for 17 cancer diagnoses, the overall proportion of episodes dedicated to bone metastases (9.4%) was stable from 2015 to 2017, although treatments were increasing in the hospital-affiliated outpatient setting (P < .005). We identified 40,993 episodes for bone metastases, of which 63% were short-course EBRT, 24% were long-course EBRT, 7% were SBRT, and 6% were IMRT. Techniques more common in the hospital-affiliated outpatient setting included short-course EBRT (OPD, 69%, vs FREE, 56%) and SBRT (OPD, 9%, vs FREE, 5%). Techniques more common among free-standing centers included long-course EBRT (OPD, 19%, vs FREE, 31%) and IMRT (OPD, 4%, vs FREE, 9%). From 2015 to 2017, long-course EBRT decreased by an absolute 8%; short-course EBRT, SBRT, and IMRT increased by 4%, 2.5%, and 1%, respectively. The SBRT/IMRT uptake did not differ by setting (P = .4). Differences in expenditures between SBRT and short-course EBRT decreased by a relative 8% in professional and 12% in technical fees.

CONCLUSIONS

Approximately 1 in 4 patients received long-course EBRT, with small reductions in use largely replaced by complex treatment modalities. However, expenditures for complex modalities also decreased over time. As alternative payment models take effect, quality metrics are needed to ensure appropriate, effective, and safe delivery of complex technologies.

Bone Metastases: Mechanisms of the Metastatic Process, Imaging and Therapy

The mechanisms by which tumors metastasize to bone are complex. Upon the successful establishment of metastatic deposits in the skeleton, detection of the disease becomes essential for therapeutic planning. The roles of CT, skeletal scintigraphy, SPECT/CT, MRI, PET/CT and PET/MRI will be reviewed. Therapeutic response criteria specifically designed to evaluate bone metastases (MD Anderson/MDA criteria) can guide image interpretation. Knowledge of therapeutic strategies such as systemic therapy with bisphosphonates or radiopharmaceuticals, radiation therapy, surgery, and percutaneous interventions such as vertebroplasty and radiofrequency ablation can help the radiologist produce reports that will provide maximum benefit to clinicians and patients.

Single-fraction stereotactic ablative body radiotherapy for sternal metastases in oligometastatic breast cancer: Technique and single institution experience

INTRODUCTION

Due to size and close proximity to skin, the sternum is a complicated target for stereotactic ablative body radiotherapy (SABR). This is a retrospective case series of single-fraction SABR to sternal metastasis in patients with oligometastatic breast cancer.

METHODS

Between June 2014 and June 2018, ten breast cancer patients received 20 Gy in 1 fraction to a solitary sternal metastasis. Eligible patients had Eastern Cooperative Oncology Group performance status of 0-2, oligometastatic disease (defined as 1-5 metastases) and a controlled primary site. Patients were treated with 3-dimensional conformal radiotherapy, each patient case comprising of> 6 coplanar beams and 2-6 non-coplanar beams. Local control, pain response and adverse events were retrospectively reviewed.

RESULTS

The median planned target volumes were 84.75cc (range, 14.4-197.8cc). The median conformity index was 1.29 (range, 1.2-1.49). At a median follow-up of 32 months, nine patients achieved in-field control. Two patients had triple negative disease, one of them developed marginal recurrence, and the other had in-field recurrence. Seven patients had sternal pain prior to SABR, and within 3 months after SABR treatment, the pain improved (n = 3) or resolved (n = 2). Four patients developed acute grade 1 and 2 skin reactions, and two patients had late grade 1 skin reactions. There were no grade 3 or 4 toxicities.

CONCLUSION

Our case series demonstrates safety of SABR with associated disease control and analgesic benefit in selected patients with oligometastatic breast cancer. The marginal recurrence observed in this cohort suggests wider margins could be beneficial to account for microscopic disease.

Metastatic disease in head & neck oncology

The head and neck district represents one of the most frequent sites of cancer, and the percentage of metastases is very high in both loco-regional and distant areas. Prognosis refers to several factors: a) stage of disease; b) loco-regional relapses; c) distant metastasis. At diagnosis, distant metastases of head and neck cancers are present in about 10% of cases with an additional 20-30% developing metastases during the course of their disease. Diagnosis of distant metastases is associated with unfavorable prognosis, with a median survival of about 10 months. The aim of the present review is to provide an update on distant metastasis in head and neck oncology. Recent achievements in molecular profiling, interaction between neoplastic tissue and the tumor microenvironment, oligometastatic disease concepts, and the role of immunotherapy have all deeply changed the therapeutic approach and disease control. Firstly, we approach topics such as natural history, epidemiology of distant metastases and relevant pathological and radiological aspects. Focus is then placed on the most relevant clinical aspects; particular attention is reserved to tumours with distant metastasis and positive for EBV and HPV, and the oligometastatic concept. A substantial part of the review is dedicated to different therapeutic approaches. We highlight the role of immunotherapy and the potential effects of innovative technologies. Lastly, we present ethical and clinical perspectives related to frailty in oncological patients and emerging difficulties in sustainable socio-economical governance.

Patient-Reported Outcomes of Oligometastatic Patients After Conventional or Stereotactic Radiation Therapy to Bone Metastases: An Analysis of the PRESENT Cohort

PURPOSE

Stereotactic body radiation therapy (SBRT) has become a widely adopted treatment for patients with oligometastatic disease, despite limited evidence of superiority. We compared pain response and quality of life (QoL) in patients with oligometastatic disease treated with conventionally fractionated 3-dimensional radiation therapy (3DCRT) or SBRT to bone metastases.

METHODS AND MATERIALS

We included patients with oligometastatic disease (≤5 lesions within ≤3 organs) treated within the prospective PRESENT cohort. Main outcomes were pain response, clinical local control, and QoL 2, 4, and 8 weeks and 3, 6, and 12 months after treatment. Pain response was assessed only in patients who reported pain at baseline and was defined according to international consensus criteria.

RESULTS

Of 131 patients with oligometastatic disease, 66 patients were treated with 3DCRT and 65 patients with SBRT. A pain response was achieved in 81% (3DCRT) versus 84% (SBRT) with a median duration of 23 weeks (range, 1-58) and 24 weeks (range, 0-50), respectively. Reirradiation was needed in 33% versus 5% of the patients, respectively. None of the QoL subscales were significantly different between both groups.

CONCLUSIONS

In patients with oligometastatic disease, SBRT to bone metastases did not improve pain response or QoL compared with 3DCRT. Reirradiation was less often needed in the SBRT group.

Predictive Analytics in Spine Oncology Research: First Steps, Limitations, and Future Directions

The potential of big data analytics to improve the quality of care for patients with spine tumors is significant. At this moment, the application of big data analytics to oncology and spine surgery is at a nascent stage. As such, efforts are underway to advance data-driven oncologic care, improve patient outcomes, and guide clinical decision making. This is both relevant and critical in the practice of spine oncology as clinical decision making is often made in isolation looking at select variables deemed relevant by the physician. With rapidly evolving therapeutics in surgery, radiation, interventional radiology, and oncology, there is a need to better develop decision-making algorithms utilizing the vast data available for each patient. The challenges and limitations inherent to big data analyses are presented with an eye towards future directions.