The biology and treatment of oligometastatic cancer

The relationship between the treatment course and prognosis of oligometastasis after esophageal squamous cell carcinoma resection

PURPOSE

The concept of oligometastasis, which represents limited metastatic disease, has recently gained interest, accompanied by a more detailed classification. This study aims to investigate the relationship between the treatment course and prognosis in patients with a recurrence of esophageal squamous cell carcinoma (ESCC) after curative esophagectomy.

METHODS

126 patients with ESCC recurrence after curative resection were enrolled in this study. Oligometastasis was defined as fewer than five recurrences in a single organ. Patients were classified as having oligometastatic recurrence (OLR) or polymetastatic recurrence (PLR). Patients were further classified into four subgroups according to lesion progression: persistent oligorecurrence (PER-OLR), converted polyrecurrence (CON-PLR), induced oligorecurrence (IND-OLR), and persistent polyrecurrence (PER-PLR). We analyzed the relationship between the recurrence patterns and prognosis according to the progression of oligometastatic lesions.

RESULTS

OLR was identified in 58 (46%) of 126 patients with recurrence. Patients with OLR had a significantly better prognosis than those with PLR (P < 0.0001). A further subgroup analysis revealed that patients who underwent IND-OLR had a similar prognosis to those who underwent PER-OLR.

CONCLUSIONS

This study suggests that OLR is a prognostic factor after recurrence following resection of ESCC and that PLR can be converted to OLR by therapeutic intervention to achieve a long-term survival.

Outcomes of Radiotherapy in Oligoprogressive Breast Cancer

INTRODUCTION

Radiotherapy (RT) shows potential for improving local control in cases of oligoprogressive metastatic breast cancer (mBC). This retrospective analysis aims to evaluate the advantages of RT in such a clinical scenario.

METHODS

We conducted a retrospective analysis including patients with mBC who received radiation therapy (RT) for up to three sites of oligoprogression while continuing systemic therapy. The study took place between January 2014 and December 2021. Our endpoints were progression-free survival after radiotherapy (PFS-AR), the rate of discontinuation of systemic therapy (RDT) at three months post-RT, and overall survival (OS). We used Cox regression analysis to perform multivariate analysis for PFS-AR.

RESULTS

Fifty-nine patients met the inclusion criteria. The PFS-AR was 13 months (95% CI 8.5-18.8 months). At three months, the RDT was 3% (two patients). A significant difference in median PFS-AR was observed between patients in the first + second-line group and those in the subsequent line group (p = 0.03). In the multivariate analysis conducted for PFS-AR, the biologically effective dose (BED) with α/β = 4 > 100 Gy emerged as the sole significant variable (p = 0.0017). The median overall survival (OS) was 24.4 months (95% CI 17-24.4 months).

CONCLUSIONS

This study is the first report on the outcomes of radiotherapy in a cohort of over 50 patients with oligoprogressive metastatic breast cancer (mBC). Our findings emphasize the significant relationship between PFS-AR, the number of ongoing lines of systemic therapy, and the BED of radiotherapy.

Ablative Radiation Therapy to Restrain Everything Safely Treatable (ARREST): A Phase 1 Study of Stereotactic Ablative Radiation Therapy for Polymetastatic Disease

PURPOSE

This phase 1 study aimed to assess the safety and feasibility of SABR therapy delivery to all sites of polymetastatic disease (>10 metastases).

METHODS AND MATERIALS

A 3 + 3 study design was used with 5 dose levels from 6 Gy (6 Gy × 1) to 30 Gy (6 Gy weekly × 5). Dose-limiting toxicity (DLT) was defined as any grade 4 or 5 toxicity or more than 3 grade 3 toxicities within 6 weeks of treatment. The primary endpoint was the maximal tolerated dose, defined as the dose level where ≥2/6 of patients experienced DLT. Secondary endpoints included quality of life (Functional Assessment of Cancer Therapy - General and European Quality of Life 5 Dimension 5 Level) at 6 weeks posttreatment, progression-free survival, and overall survival.

RESULTS

Thirteen patients were accrued: 12 Gy (n = 3), 18 Gy (n = 3), 24 Gy (n = 4), and 30 Gy (n = 3), and 207 lesions were treated. Nine patients (69%) had acute toxicity: grade 1 (n = 6, 46%), grade 2 (n = 2, 15%; n = 1 pneumonitis and n = 1 fatigue), and grade 3 (n = 1, 7.7% neutropenia). There were no grade 4 or 5 toxicities. Mean ± SD quality of life (Functional Assessment of Cancer Therapy - General and European Quality of Life 5 Dimension 5 Level health state) was 80.4 ± 21.9 and 77.4 ± 20.9 at baseline versus 76.4 ± 21.8 and 68.0 ± 24.2 at 6-week follow-up, respectively (p = .009 and p = .055, respectively). With a median follow-up of 8.7 months posttreatment (IQR, 2.4-24 months), 8 of 13 patients had disease progression (62%). The median and 12-month progression-free survival were 3.6 months and 11.3%, respectively. The median and 12-month overall survival were 13.8 months and 62%, respectively.

CONCLUSIONS

In this phase 1 trial, SABR therapy for polymetastatic disease was technically feasible with acceptable acute toxicity at dose levels up to 30 Gy (6 Gy weekly × 5). DLT was not observed.

Balancing Hormone Therapy: Mitigating Adverse Effects of Androgen-Deprivation Therapy and Exploring Alternatives in Prostate Cancer Management

Androgen-deprivation therapy (ADT) is well established as the standard of care in metastatic prostate cancer (PCa) management; however, ADT has significant adverse effects (AEs) that must be addressed. This review aims to highlight opportunities to mitigate AEs of ADT and explore alternatives in PCa management. Specifically, we discuss behavioral and pharmacologic strategies for mitigating ADT AEs as well as ADT-sparing approaches for hormone-sensitive and castration-resistant PCa. Equipped with effective mitigation strategies and possible alternatives, clinicians and researchers can optimize health-related quality of life for patients currently receiving ADT for PCa and consider treatments that spare patients from AEs of ADT.

Advances in the Surgical Management of Esophageal Cancer

Radical esophagectomy with two or three-field lymphadenectomy remains the mainstay of curative treatment for localized esophageal cancer, often in combination with systemic chemotherapy and/or radiotherapy. In this article, we describe notable advances in the surgical management of esophageal cancer over the past decade that have led to an improvement in both surgical and oncologic outcomes. In addition, we discuss new approaches to surgical management currently under investigation that have the potential to offer further benefits to appropriately selected patients. These incremental breakthroughs primarily include advances in endoscopic and minimally invasive techniques, perioperative management protocols, as well as the application of local therapies, including surgery, to oligometastatic disease.

Navigating Breast Cancer Oligometastasis and Oligoprogression: Current Landscape and Future Directions

PURPOSE

We examine the potential for curative approaches among metastatic breast cancer (MBC) patients by exploring the recent literature on local ablative therapies like surgery and stereotactic body radiation therapy (SBRT) in patients with oligometastatic (OM) breast cancer. We also cover therapies for MBC patients with oligoprogressive (OP) disease.

KEY FINDINGS

Surgery and SBRT have been studied for OM and OP breast cancer, mainly in retrospective or non-randomized trials. While many studies demonstrated favorable results, a cooperative study and single-institution trial found no support for surgery/SBRT in OM and OP cases, respectively.

CONCLUSION

While there is interest in applying local therapies to OM and OP breast cancer, the current randomized data does not back the routine use of surgery or SBRT, particularly when considering the potential for treatment-related toxicities. Future research should refine patient selection through advanced imaging and possibly explore these therapies specifically in patients with hormone receptor-positive or HER2-positive disease.

Definitions, outcomes and perspectives for oligometastatic bladder cancer: towards a standardized terminology

PURPOSE OF REVIEW

Oligometastatic (om) cancer is considered as a transitional state in between locally confined disease and widespread metastases, accessible to a multimodal treatment, combining systemic and local therapy. In urothelial bladder cancer (BCa), the definitions and the approaches to this condition are poorly standardised and mainly based on retrospective data. We aim to portray the framework for uro-oncologic terminology in omBCa and go through the latest evidence and the future perspectives.

RECENT FINDINGS

Retrospective and registry data support the potential benefits of multimodality treatment for carefully selected omBCa patients, especially following a good response to systemic treatment. In 2023, a Delphi consensus has defined omBCa, allowing maximum three metastatic lesions, theoretically amenable to radical local treatment. In de-novo omBCa, surgical treatment of primary tumour might improve overall survival (OS), according to a matched registry analysis; also, consolidative radiotherapy was associated with better OS in two recent cohorts. Furthermore, metastasis-directed therapy (MDT) has shown high local control rates and promising OS (14.9-51 months) in a meta-analysis; benefits might be more pronounced for single-site omBCa and nodal or lung lesions.

SUMMARY

From a clinical perspective, in de-novo omBCa, the local treatment of primary and metastatic sites might improve disease control and survival, in selected patients; in the oligorecurrent setting, MDT achieves good local symptom control with limited side effects; in selected cases, it could convey a survival benefit, too. From a research perspective, well designed prospective evidence is eagerly awaited, based on recently adopted shared definitions for omBCa.

A systematic review of cytoreductive prostatectomy outcomes and complications in oligometastatic disease

Objective

To analyze outcomes and complications of cytoreductive prostatectomy (CRP) for oligometastatic prostate cancer (PCa) in order to elucidate its role in this space.

Methods

We performed a systematic literature search using three databases (Medline, Scopus, and Web of Science). The primary endpoints were oncologic outcomes. The secondary endpoints were complication rates and functional results.

Results

In all studies, overall survival was better or at least comparable variable in the groups with CRP compared to no local treatment. The greatest benefit from CRP in 5-year overall survival in one study was 67.4% for CRP versus 22.5% for no local treatment. Cancer-specific survival (CSS) showed the same trend. Several authors found significant benefits from CSS in the CRP group: from 79% vs. 46% to 100% vs. 61%. CRP was a predictor of better CSS (hazard ratio 0.264, p=0.004). Positive surgical margin rates differed widely from 28.6% to 100.0%. Urinary continence in CRP versus RP for localized PCa was significantly lower (57.4% vs. 90.8%, p<0.0001). Severe incontinence occurred seldom (2.5%-18.6%). Total complication rates after CRP differed widely, from 7.0% to 43.6%. Rates of grades 1 and 2 events prevailed. Patients on ADT alone also showed a considerable number of complications varying from 5.9% to 57.7%.

Conclusion

CRP improves medium-term cancer control in patients with oligometastatic PCa. The morbidity and complication rates of this surgery are comparable with other approaches, but postoperative incontinence rate is higher compared with RP for localized disease.

Role of Interventional Radiology in Managing Primary and Metastatic Breast Cancer

Percutaneous image-guided locoregional therapies are emerging in the treatment of primary and metastatic breast cancer. Cryoablation has emerged as the dominant ablative approach as an alternative to surgery for primary breast cancer in patients who do not wish to have surgery or are poor surgical candidates. Cryoablation is well tolerated and provides excellent local control and cosmesis. Thermal ablation may also be used in the treatment of oligometastatic breast cancer, allowing patients to achieve long disease-free intervals. Transarterial therapies have been studied in the treatment of oligoprogressive hepatic metastasis, though further supportive data would be helpful to demonstrate its efficacy.

A Prospective Study Assessing the Efficacy and Toxicity of Stereotactic Body Radiation Therapy for Oligometastatic Bone Metastases

Purpose

Stereotactic body radiation therapy (SBRT) is a promising treatment for oligometastatic disease in bone because of its delivery of high dose to target tissue and minimal dose to surrounding tissue. The purpose of this study is to assess the efficacy and toxicity of this treatment in patients with previously unirradiated oligometastatic bony disease.

Methods and Materials

In this prospective phase II trial, patients with oligometastatic bone disease, defined as ≤3 active sites of disease, were treated with SBRT at Brigham and Women's Hospital/Dana Farber Cancer Center and Beth Israel Deaconess Medical Center between December 2016 and May 2019. SBRT dose and fractionation regimen were not protocol mandated. Local progression-free survival, progression-free survival, prostatic specific antigen progression, and overall survival were reported. Treatment-related toxicity was also reported.

Results

A total of 98 patients and 126 lesions arising from various tumor histologies were included in this study. The median age of patients enrolled was 72.8 years (80.6% male, 19.4% female). Median follow-up was 26.7 months. The most common histology was prostate cancer (68.4%, 67/98). The most common dose prescriptions were 27/30 Gy in 3 fractions (27.0%, 34/126), 30 Gy in 5 fractions (16.7%, 21/126), or 30/35 Gy in 5 fractions (16.7%, 21/126). Multiple doses per treatment regimen reflect dose painting employing the lower dose to the clinical target volume and higher dose to the gross tumor volume. Four patients (4.1%, 4/98) experienced local progression at 1 site for each patient (3.2%, 4/126). Among the entire cohort, 2-year local progression-free survival (including death without local progression) was 84.8%, 2-year progression-free survival (including deaths as well as local, distant, and prostatic specific antigen progression) was 47.5%, and 2-year overall survival was 87.3%. Twenty-six patients (26.5%, 26/98) developed treatment-related toxicities.

Conclusions

Our study supports existing literature in showing that SBRT is effective and tolerable in patients with oligometastatic bone disease. Larger phase III trials are necessary and reasonable to determine long-term efficacy and toxicities.

Stereotactic body radiation therapy for adrenal gland metastases: A multi-institutional outcome analysis

Aim

The adrenal gland is a common site of metastasis with a rate of up to 27% in autopsy series. The incidence of these metastases is increasing due to greater use of Positron Emission Tomography scans and improved overall survival of patients with metastatic cancers. Stereotactic body radiation therapy (SBRT) is a non-invasive treatment option for metastasis. The aim of this study is to assess prognostic factors influencing local control, progression-free and overall survival in oligometastatic patients treated with SBRT for an adrenal metastasis.

Methods

In this multicentric retrospective study, we included patients with adrenal metastases treated with SBRT between 2010 and 2021 in eleven french centers. All primary tumors were included.

Results

A total of 110 patients treated for 121 adrenal lesions were included. Non-small-cell lung cancer was the predominant histologic type (55.4 %). Eighty-two percent of patients had at least 2 metastatic sites. The median Planning Target Volume was 70 cm3 with a median prescription dose of 40 Gray (Gy). The mean Biologically Effective Dose (BED) 10 dose was 74.2 Gy. Local control at 1 and 2 years was 85.9 % and 72.5 % respectively. The median overall survival and progression-free survival were 31.6 and 8.5 months respectively. Local control was significantly improved by systemic treatment one month before or after SBRT (p = 0.009) and by a BED10 greater than or equal to 50 Gy (p = 0.003).In multivariate analysis, oligometastatic presentation (p = 0.009) and a metachronous metastatic presentation (p = 0.008) were independent factors for progression-free survival.Tolerance was excellent, no grade 3 and 4 toxicities were described due to SBRT.

Conclusion

Stereotactic radiotherapy of adrenal metastases makes possible a local control of more than 85% at one year and was well tolerated. The factors influencing survival in oligometastatic patients still need to be found in order to better select those who benefit the most from this type of treatment.

The role of radiation therapy for de novo metastatic bladder and renal cancers

Metastatic bladder and renal cancers account respectively for 2.1% and 1.8% of cancer deaths worldwide. The advent of immune checkpoint inhibitors has revolutionized the management of metastatic disease, by demonstrating considerable improvements in overall survival. However, despite initial sensitivity to immune checkpoint inhibitors for most patients, both bladder and renal cancer are associated with short progression-free survival and overall survival, raising the need for further strategies to improve their efficacy. Combining systemic therapies with local approaches is a longstanding concept in urological oncology, in clinical settings including both oligometastatic and polymetastatic disease. Radiation therapy has been increasingly studied with either cytoreductive, consolidative, ablative or immune boosting purposes, but the long-term impact of this strategy remains unclear. This review intends to address the impact of radiation therapy with either curative or palliative intent, for synchronous de novo metastatic bladder and renal cancers.

Magnetic resonance-guided focused ultrasound versus percutaneous thermal ablation in local control of bone oligometastases: a systematic review and meta-analysis

BACKGROUND

The percutaneous thermal ablation techniques (pTA) are radiofrequency ablation, cryoablation, and microwave ablation, suitable for the treatment of bone oligometastases. Magnetic resonance-guided focused ultrasound (MRgFUS) is a noninvasive ablation technique.

OBJECTIVES

To compare the effectiveness and safety of MRgFUS and pTA for treating bone oligometastases and their complications.

METHODS

Studies were selected with a PICO/PRISMA protocol: pTA or MRgFUS in patients with bone oligometastases; non-exclusive curative treatment. Exclusion criteria were: primary bone tumor; concurrent radiation therapy; palliative therapy; and absence of imaging at follow-up. PubMed, BioMed Central, and Scopus were searched. The modified Newcastle-Ottawa Scale assessed articles quality. For each treatment (pTA and MRgFUS), we conducted two separate random-effects meta-analyses to estimate the pooled effectiveness and safety. The effectiveness was assessed by combining the proportions of treated lesions achieving local tumor control (LTC); the safety by combining the complications rates of treated patients. Meta-regression analyses were performed to identify any outcome predictor.

RESULTS

A total of 24 articles were included. Pooled LTC rate for MRgFUS was 84% (N = 7, 95% CI 66-97%, I2 = 74.7%) compared to 65% of pTA (N = 17, 95% CI 51-78%, I2 = 89.3%). Pooled complications rate was similar, respectively, 13% (95% CI 1-32%, I2 = 81.0%) for MRgFUS and 12% (95% CI 8-18%, I2 = 39.9%) for pTA, but major complications were recorded with pTA only. The meta-regression analyses, including technique type, study design, tumor, and follow-up, found no significant predictors.

DISCUSSION

The effectiveness and safety of the two techniques were found comparable, even though MRgFUS is a noninvasive treatment that did not cause any major complication. Limited data availability on MRgFUS and the lack of direct comparisons with pTA may affect these findings.

CONCLUSIONS

MRgFUS can be a valid, safe, and noninvasive treatment for bone oligometastases. Direct comparison studies are needed to confirm its promising benefits.

Long-term outcomes of metastasis-directed stereotactic body radiation therapy in metastatic nasopharyngeal carcinoma

BACKGROUND

The study aims to evaluate the outcomes of metastasis-directed stereotactic body radiation therapy (SBRT) in metastatic nasopharyngeal carcinoma (mNPC).

METHODS

We reviewed all SBRT conducted in patients with mNPC in our institution between 2013 and 2022. Systemic therapy was performed with chemotherapy with or without anti-programmed death-1 (PD-1) therapy. Local treatment delivered with ablative purpose in stereotactic setting with dose/fraction ≥5 Gy was evaluated. Kaplan-Meier analyses were used to determine the rates of local control (LC), progression-free survival (PFS), and overall survival (OS). Univariate and multivariate analyses were performed by Cox regression.

RESULTS

A total of 54 patients with 76 metastatic sites receiving SBRT were analyzed. Median follow-up was 49 months. The 3-year LC, PFS, and OS rates were 89.1%, 29.4%, and 57.9%, respectively. Adding a PD-1 inhibitor to SBRT tended to prolong median OS (50.1 vs. 32.2 months, p = 0.068). Patients receiving a biological effective dose (BED, α/β = 10) ≥ 80 Gy had a significantly longer median OS compared to those who received a lower dose (not reached vs. 29.5 months, p = 0.004). Patients with oligometastases (1-5 metastases) had a better median OS (not reached vs. 29.5 months, p < 0.001) and PFS (34.3 vs. 4.6 months, p < 0.001). Pretreatment EBV-DNA and maintenance therapy were also significant predictors for OS.

CONCLUSIONS

Metastatic NPC patients could benefit from metastases-directed SBRT in combination with systemic therapy.

The diagnosis and treatment of castrate-sensitive oligometastatic prostate cancer: A review

BACKGROUND

Oligometastatic prostate cancer (OMPCa) is emerging as a transitional disease state between localized and polymetastatic disease. This review will assess the current knowledge of castrate-sensitive OMPCa.

METHODS

A review of the current literature was performed to summarize the definition and classification of OMPCa, assess the diagnostic methods and imaging modalities utilized, and to review the treatment options and outcomes. We further identify gaps in knowledge and areas for future research.

RESULTS

Currently there is no unified definition of OMPCa. National guidelines mostly recommend systemic therapies without distinguishing oligometastatic and polymetastatic disease. Next generation imaging is more sensitive than conventional imaging and has led to early detection of metastases at initial diagnosis or recurrence. While mostly retrospective in nature, recent studies suggest that treatment (surgical or radiation) of the primary tumor and/or metastatic sites might delay initiation of androgen deprivation therapy while increasing survival in selected patients.

CONCLUSIONS

Prospective data are required to better assess the incremental improvement in survival and quality of life achieved with various treatment strategies in patients with OMPCa.

Is there a role for radical prostatectomy in the management of oligometastatic prostate cancer? A systematic review

CONTEXT

There is a growing interest about the role of radical prostatectomy (RP) in local cancer control in oligometastatic prostate cancer (PCa).

PURPOSE

To evaluate the oncological and functional outcomes of RP in the management of oligometastatic PCa through a systematic review.

METHODS

A systematic review search was performed and the following bibliographic databases were accessed: PubMed, Scopus, Embase and the Cochrane central register of controlled trials were searched from January 2000 to November 2022. This was carried out by the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) guidelines.

RESULTS

Based on the literature search of 384 articles, 11 (511 patients) met the inclusion criteria (mean age: 65.5 yr.). Positive surgical margins were 59%. Median follow-up ranged from 13 to 64 months. Clinical progression-free survival ranged from 56% at 3 years to 45% at 7 years. Specific and overall survival rates ranged from 60 to 80.5% and 78 to 80% at 5 years, respectively. Clavien ≥3 complications ranged from 0 to 21%. The urinary incontinence rate was 14.5%.

CONCLUSIONS

Similar to published studies, RP of oligometastatic PCa appears to be safe with acceptable morbidity in selected patients. The lack of a consensual definition, the low level of evidence and the bias of the comparative and retrospective studies available do not allow practical recommendations to be made. There is currently no place for metastatic surgery outside of participation in a clinical trial.

Relationship Between Metabolic Activity, Cellularity, Histopathological Features of Primary Tumors and Distant Metastatic Potential in Breast Cancer

Objectives

The aim of this study was to evaluate the relationship between the types of distant metastatic spread, histopathological features, and imaging features of primary tumor on positron emission tomography/magnetic resonance imaging (PET/MRI) for primary staging in newly diagnosed breast invasive ductal carcinoma (IDC) patients.

Methods

Data from 289 female patients were retrospectively evaluated. Maximum standardized uptake value, metabolic tumor volume (MTV), total lesion glycolysis (TLG), and minimum apparent diffusion coefficient (ADCmin) values of primary tumors were obtained from PET/MRI. The patients were grouped as non-metastatic, oligometastatic (1-5 metastatic lesions) and multimetastatic (>5 metastatic lesions) disease according to the number of distant metastases, and divided into two groups as isolated bone metastasis (IBM) and mixed/soft tissue metastasis (M-SM) groups according to the sites of metastatic spread.

Results

Metabolic parameters had higher values and ADCmin had lower values in the multimetastatic and oligometastatic groups than in the non-metastatic group. MTV was the only parameter that showed significant difference between the multimetastatic and oligometastatic groups. MTV and TLG were significantly higher in the M-SM group than in the IBM group. 18F-fluorodeoxyglucose PET parameters had significantly higher values in grade 3, hormone receptor negative, human epidermal growth factor receptor 2 positive, triple negative, and highly proliferative (Ki-67 ≥14%) tumors. The prediction models that included imaging parameters to predict the presence of distant metastasis had higher discriminatory powers than the prediction models that included only histopathological parameters.

Conclusion

Primary tumors with higher metabolic-glycolytic activity and higher cellularity were more aggressive and had higher metastatic potential in breast IDC. Compared with histopathological parameters alone, the combination of imaging parameters and histopathological features of primary tumors may help to better understand tumor biology and behavior.

RIFLE: a Phase II trial of stereotactic ablative radiotherapy combined with fruquintinib and tislelizumab in metastatic colorectal cancer

Background

Currently, the prognosis for metastatic colorectal cancer (mCRC) still remains poor. The management of mCRC has become manifold because of the varied advances in the systemic and topical treatment approaches. For patients with limited number of metastases, radical local therapy plus systemic therapy can be a good choice to achieve long-term tumor control. In this study, we aimed to explore the efficacy and safety of the combination of fruquintinib, tislelizumab, and stereotactic ablative radiotherapy (SABR) in mCRC (RIFLE study).

Methods

RIFLE was designed as a single-center, single-arm, prospective Phase II clinical trial. A total of 68 mCRC patients who have failed the first-line standard treatment will be recruited in the safety run-in phase (n = 6) and the expansion phase (n = 62), respectively. Eligible patients will receive SABR followed by fruquintinib (5 mg, d1-14, once every day) and tislelizumab (200 mg, d1, once every 3 weeks) within 2 weeks from completion of radiation. The expansion phase starts when the safety of the treatment is determined (dose limiting toxicity occur in no more than one-sixth of patients in the run-in phase). The primary end point is the objective response rate. The secondary end points include the disease control rate, duration of response, 3-year progression-free survival rate, 3-year overall survival rate, and toxicity.

Conclusions

The results of this trial will provide a novel insight into SABR in combination with PD-1 antibody and vascular endothelial growth factor receptor inhibitor in the systematic treatment of metastatic colorectal cancer, which is expected to provide new therapeutic strategies and improve the prognosis for mCRC patients.

Trial registration

NCT04948034 (ClinicalTrials.gov).

Case Report: Stereotactic body radiation treatment for immunotherapy escaped oligometastatic progression in cutaneous melanoma and merkel cell carcinoma

Oligometastatic progression represents a unique manifestation of tumor immune-escape that can lead to disease progression during treatment with immune checkpoint inhibitor (ICI). The diagnosis and further optimal management of oligometastatic progression through ICI remains unclear. Diagnostic challenges include practical limitations due to the anatomical sites of oligometastatic progression, such as the para-aortic region, where traditional tissue biopsy carries high risk, and circulating-tumor DNA (ctDNA) could aid in diagnosis and disease monitoring as a supplement to surveillance imaging. In this report, we describe two cases of one patient with metastatic melanoma and the other with metastatic Merkel cell carcinoma (MCC) who were treated with ICI and later developed localized resistance due to oligometastatic progression. We further highlight our experience using stereotactic body radiation therapy (SBRT) as a salvage approach to treat the oligometastatic progression. In addition, we describe the temporal and dynamic relationship of circulating-tumor DNA (ctDNA) prior to, during and after SBRT, which highly suggested the diagnosis without obtaining a histological specimen. Our cases highlight a potential role for SBRT in the management of oligometastatic progression. However, large prospective trials are essential to confirm the utility of this approach.

An Environmental Scan of Advanced Practice Radiation Therapy in the United States: A PESTEL Analysis

PURPOSE

In 2021, the Advanced Practice Radiation Therapy Working Group (APRTWG) was established in the United States as a grassroots alliance of multidisciplinary radiation oncology professionals-radiation therapists, physicians, dosimetrists, and administrators-located across the country, interested in studying and establishing the Advanced Practice Radiation Therapist (APRT) level of practice in the United States. The APRT model has shown success in the United Kingdom, Canada, Australia, Singapore, and other countries, documenting the value of the APRT to the quality and advancement of clinical care. In the United States, the APRTWG seeks to coordinate activities, align resources, and drive the national agenda to collectively develop and define novel models of care using APRT in line with the evolving needs of patients and the radiation therapy profession. This environmental scan aims to examine the context of radiation oncology medical practice in the United States to inform pathways ahead for a proposed APRT model through a Political, Economic, Social, Technological, Environmental, and Legal (PESTEL) analysis.

METHODS AND MATERIALS

A literature search was conducted to understand the chronological timeline of the development of APRT during the past 25 years. Items that included the activities, scope of practice, and implementation of APRT nationally and internationally were identified. Papers describing advanced practitioner roles that are commonly found in the multidisciplinary team in radiation oncology both in the United States and internationally, such as physician assistants and nurse practitioners, were excluded.

RESULTS

Despite the environmental scan outcome, it is acknowledged that data collation and analysis was not as robust as that anticipated by undertaking a systematic review. Papers were identified by the lead author that aligned with each of the PESTEL factors. Defined broadly, a new care model can adjust how health services are delivered by incorporating best practices in patient care for a specific population, person, or patient cohort. As patients enter different stages of their disease, the purpose of a new model is to provide individuals with the right care, at the right time, by the right team, in the right place. It is clear that the opportunity for positive change and impact on the current state of practice in radiation oncology exists.

CONCLUSION

The environmental scan findings demonstrate the complexities associated with implementing APRT in the United States, with multifactorial political, environmental, societal, technological, economic, and legal aspects to consider. The APRTWG will continue to lead and participate in such activities to demonstrate and identify APRT role opportunities in the United States and drive the nationwide implementation of the APRT level of practice in this country.

Defining Oligometastatic Bladder Cancer: A Systematic Review

Context

Unlike other cancers, the concept of oligometastatic disease (OMD) in bladder cancer (BC) has not been systematically investigated. There is therefore a need to develop universally accepted definitions and guidelines for the management of oligometastatic BC (OMBC).

Objective

To conduct a systematic review to assist a European consensus group in producing a definition of OMBC and to provide recommendations on staging and local therapies.

Evidence acquisition

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. Abstracts for articles focused on BC that addressed the issue of OMBC and provided a definition of oligometastatic status were selected. We collected data on the number of metastases, the number of metastases per organ, the number of organs involved, and metastatic sites that were excluded.

Evidence synthesis

Sixteen eligible articles were retrieved (9 retrospective series involving 330 patients, 4 reviews, 1 consensus statement, 1 guideline paper, and 1 ongoing prospective phase 2 trial). A maximum of three to five metastatic lesions were compatible with the definition of OMBC. The number of organs involved and lesion size were not universally included in the OMBC definitions. OMD categories studied included synchronous OMBC, oligorecurrence, and oligoprogression. 18F-Fluorodeoxyglucose positron emission tomography combined with computed tomography was used in addition to conventional imaging for OMD detection. Surgery and radiotherapy were both used. Systemic chemotherapy was also used in all studies.

Conclusions

There is little information on OMBC in the literature. Our systematic review revealed that only three to five metastatic sites amenable to surgery or radiotherapy that respond to systemic therapy is the setting most frequently chosen for a combination of systemic treatment and metastases-directed therapy. This setting could represent a basis for future prospective studies on OMBC.

Patient summary

Oligometastatic bladder cancer is a disease state in which favorable outcomes can be expected after a treatment combination of systemic therapy, plus surgery and/or radiotherapy for sites of bladder cancer metastasis. Our systematic review showed a lack of meaningful evidence to define this disease state. There is an urgent need to develop organized research in this field.

Characterization of the Tumor Microenvironment of De Novo Oligometastatic Breast Cancer in a Nationwide Cohort

PURPOSE

Oligometastatic breast cancer (OMBC) has a more favorable outcome than widespread metastatic breast cancer. Some patients with OMBC achieve long-term remission if treated with multimodality therapy, including systemic and locally ablative therapies. However, not all patients with OMBC benefit from such treatment, while all experience toxicity. To explore biomarkers identifying patients with OMBC and potential long-term survival, we compared tumor-immune characteristics of patients with OMBC and long-term versus shorter-term survival.

MATERIALS AND METHODS

We collected tumor tissue of 97 patients with de novo OMBC (≤5 metastases) via the Dutch nationwide cancer and pathology registries using a case-control design. Long-term survivors (LTS) were defined as patients alive ≥10 years since OMBC diagnosis. Fifty-five LTS and 42 shorter-term survivors (STS) were included. Median follow-up was 15 years (IQR, 14-16). Tumor characteristics and infiltrating immune cells were assessed by immunohistochemistry and next-generation RNA-sequencing. Association of the resulting 52 biomarkers with long-term survival was assessed using logistic regression. Associations with survival within LTS were assessed using Cox-proportional hazards modeling. P values were adjusted for multiple hypothesis testing.

RESULTS

Most patients had estrogen receptor (ER)-positive OMBC (n = 86; 89%) and 23 (24%) had human epidermal growth factor receptor 2-positive disease. ER positivity in primary tumors distinguished LTS from STS. In addition, extracellular matrix (ECM)2-low and ECM4-high distinguished between long-term and shorter-term survival. Immune levels in the primary tumor did not associate with LTS. However, within the LTS subset, higher immune levels associated with improved progression-free survival.

CONCLUSION

We identified tumor and ECM features in the primary tumor of patients with de novo OMBC that were associated with long-term survival. Our data should be validated in other patients with OMBC before they can be used in clinical practice.

Metastatic renal cell carcinoma to the small bowel 6 years postnephrectomy

Renal cell carcinoma (RCC) is an unpredictable malignancy, with 25%-30% of patients developing metastatic disease. The most common sites of metastasis are the lung, bones, liver and brain, with small intestine metastasis being minimally reported in the literature. This report describes a case of small bowel obstruction caused by metastatic RCC in a male patient in his 60 s who had previously undergone a radical nephrectomy with adjuvant pembrolizumab therapy 6 years prior. The patient underwent a diagnostic laparoscopy converted to a laparotomy due to the complexity of the case. During surgical exploration, an enterectomy and end-to-end anastomosis were performed. This case emphasises the possibility of RCC metastasising to the small intestine, which may present with small bowel obstruction, while highlighting the importance of patient education for early detection to improve prognosis. Additionally, this report discusses treatment options for managing RCC metastasis to the small intestine.

Impact of 18F-fluciclovine PET/CT on plans for androgen deprivation therapy in patients with biochemical recurrence of prostate cancer: data analysis from two prospective clinical trials

INTRODUCTION

Despite early detection and primary therapy improvements, biochemical recurrence (BCR) of prostate cancer remains common. The advent of highly sensitive molecular imaging has facilitated identification of men with limited metastatic disease burden that might be more optimally treated with metastases-directed therapy than with androgen deprivation therapy (ADT). The LOCATE (NCT02680041) and FALCON (NCT02578940) trials assessed the impact of 18F-fluciclovine PET/CT on the management of patients with BCR after curative-intent primary therapy. We performed a secondary analysis of LOCATE and FALCON data to characterize sites of recurrence and management decisions for BCR patients who had an intended management plan including ADT prior to undergoing 18F-fluciclovine PET/CT.

METHODS

Data from 317 LOCATE/FALCON patients who underwent 18F-fluciclovine PET/CT were analyzed and those with a prescan plan for ADT (± another treatment) were selected. 18F-Fluciclovine detection rates were determined at the patient level and for the prostate/prostate bed region, pelvic and extra-pelvic lymph nodes (LN), soft tissues, and bones. The patients' pre- and postscan treatment plans were compared and were stratified by imaging results.

RESULTS

A total of 146 patients had a prescan plan for ADT (60 as monotherapy and 86 in combination with another modality). 18F-Fluciclovine detected lesions in 85 of 146 (58%) patients planned for ADT. Detection rates in the prostate/bed, pelvic LN, extra-pelvic LN, soft tissues and bone were 30%, 25%, 13%, 2.1%, and 13%, respectively. Twenty-five (17%) patients had positivity confined to the prostate/bed, 21 (14%) had 18F-fluciclovine-positive pelvic LN (±prostate/bed) but no other involvement and 39 (27%) had involvement outside the prostate/bed and pelvic LN. Postscan, 93 of 146 (64%) patients had a management change, 55 (59%) of which were to abort ADT. Only 25% of the patients originally planned for ADT monotherapy still had an unaltered plan for ADT monotherapy postscan. Patients with a postscan plan for ADT monotherapy had the most disseminated disease. Disease in the prostate/bed only was most common in those whose plan was altered to abort ADT.

CONCLUSIONS

18F-Fluciclovine-PET/CT influenced management plans for the majority of patients with a prescan plan for ADT. Plans were commonly amended to target salvage therapy for lesions identified with 18F-fluciclovine PET/CT, and consequently likely spared/delayed patients the morbidity associated with ADT.

Clinical and pathological characterization of 158 consecutive and unselected oligometastatic breast cancers in a single institution

PURPOSE

Data about incidence, biological, and clinical characteristics of oligometastatic breast cancer (OMBC) are scarce. However, these data are essential in determining optimal treatment strategy. Gaining knowledge of these elements means observing and describing large, recent, and consecutive series of OMBC in their natural history.

METHODS

We collected data retrospectively at our institution from 998 consecutive patients diagnosed and treated with synchronous or metachronous metastatic breast cancer (MBC) between January 2014 and December 2018. The only criterion used to define OMBC was the presence of one to five metastases at diagnosis.

RESULTS

Of 998 MBC, 15.8% were classified OMBC. Among these, 88% had one to three metastases, and 86.7% had only one organ involved. Bone metastases were present in 52.5% of cases, 20.9% had progression to lymph nodes, 14.6% to the liver, 13.3% to the brain, 8.2% to the lungs, and 3.8% had other metastases. 55.7% had HR+/HER2- OMBC, 25.3% had HER2+OMBC, and 19% had HR-/HER2- OMBC. The HR+/HER2- subtype statistically correlated with bone metastases (p = 0.001), the HER2+subtype with brain lesions (p = 0.001), and the HR-/HER2- subtype with lymph node metastases (p = 0.008). Visceral metastases were not statistically associated with any OMBC subtypes (p = 0.186). OMBC-SBR grade III was proportionally higher than in the ESME series of 22,109 MBC (49.4% vs. 35.1%, p < 0.001).

CONCLUSION

OMBC is a heterogeneous entity whose incidence is higher than has commonly been published. Not an indolent disease, each subgroup, with its biological and anatomical characteristics, merits specific management.

Retrospective Analysis of a Cohort of Patients with Metastatic Bladder Cancer with Metastatic Sites Limited to the Pelvis and Retroperitoneum Treated at a Single Institution between 2009 and 2020

Bladder cancer (BC) presenting with pelvic and retroperitoneal lymph nodes presents a therapeutic challenge. The impact of chemoradiotherapy on pelvic and retroperitoneal lymph node metastasis as a consolidation treatment has not been established. Between 2009 and 2020, 502 patients who were treated with first-line chemotherapy for BC in our center, were retrospectively identified. Patients who received chemoradiotherapy or radiotherapy with an equivalent radiation dose superior to 30 Gy were included in the RTCT group, and other patients were included in the control group (CT group). We performed an analysis of progression-free survival (PFS) and overall survival (OS) for these two cohorts using the Kaplan–Meier method. A total of 89 patients were included, 24 in the RTCT group and 65 in the CT group. Chemoradiotherapy improved both OS (p = 0.034) and PFS (p = 0.009) in comparison with chemotherapy alone: 26.3 months (95% IC 0.0–52.9) and 19.4 months (95% IC 5.0–33.7), respectively, in the RTCT group versus 17.2 months (95% IC 13.7–20.6) and 11.2 months (95% IC 8.6–13.8), respectively, in the CT group. Grade 3/4 toxicity was related to chemotherapy and to chemoradiotherapy at levels of 31% and 24%, respectively. For mBC with metastatic regional or retroperitoneal lymph nodes, chemoradiotherapy seems to confer benefits for both OS and PFS.

Proposal for a Two-Tier Re-classification of Stage IV/M1 domain of Renal Cell Carcinoma into M1 (“Oligometastatic”) and M2 (“Polymetastatic”) subdomains: Analysis of the Registry for Metastatic Renal Cell Carcinoma (REMARCC)

Purpose

We hypothesized that two-tier re-classification of the “M” (metastasis) domain of the Tumor-Node-Metastasis (TNM) staging of Renal Cell Carcinoma (RCC) may improve staging accuracy than the current monolithic classification, as advancements in the understanding of tumor biology have led to increased recognition of the heterogeneous potential of metastatic RCC (mRCC).

Methods

Multicenter retrospective analysis of patients from the REMARCC (REgistry of MetAstatic RCC) database. Patients were stratified by number of metastases into two groups, M1 (≤3, “Oligometastatic”) and M2 (&gt;3, “Polymetastatic”). Primary outcome was overall survival (OS). Secondary outcomes were cancer-specific survival (CSS). Cox-regression and Kaplan-Meier (KMA) analysis were utilized for outcomes, and receiver operating characteristic analysis (ROC) was utilized to assess diagnostic accuracy compared to current “M” staging.

Results

429 patients were stratified into proposed M1 and M2 groups (M1 = 286/M2 = 143; median follow-up 19.2 months). Cox-regression revealed M2 classification as an independent risk factor for worsened all-cause mortality (HR=1.67, p=0.001) and cancer-specific mortality (HR=1.74, p&lt;0.001). Comparing M1-oligometastatic vs. M2-polymetastatic groups, KMA revealed significantly higher 5-year OS (36% vs. 21%, p&lt;0.001) and 5-year CSS (39% vs. 17%, p&lt;0.001). ROC analyses comparing OS and CSS, for M1/M2 reclassification versus unitary M designation currently in use demonstrated improved c-index for OS (M1/M2 0.635 vs. unitary M 0.500) and CSS (M1/M2 0.627 vs. unitary M 0.500).

Conclusion

Subclassification of Stage “M” domain of mRCC into two clinical substage categories based on metastatic burden corresponds to distinctive tumor groups whose oncological potential varies significantly and result in improved predictive capability compared to current staging.

Outcome of patients with biochemical recurrence of prostate cancer after PSMA PET/CT-directed radiotherapy or surgery without systemic therapy

BACKGROUND

Radiotherapy (RT) and surgery are potential treatment options in patients with biochemical recurrence (BCR) following primary prostate cancer treatment. This study examines the value of prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT)-informed surgery and RT in patients with BCR treated without systemic therapy.

METHODS

This is a post-hoc subgroup analysis of a prospective clinical trial. Inclusion criteria were: histologically proven prostate cancer at initial curative-intent treatment, BCR after primary treatment with curative intent, having five or fewer lesions identified on [¹⁸F]DCFPyL PET/CT, and treatment with either PET/CT-directed RT or surgery without systemic therapy. The biochemical progression-free survival after PSMA ligand PET/CT-directed RT and surgery was determined. Uni- and multivariate Cox regression analyses were performed for the association of patients' characteristics, tumor-specific variables, and PSMA PET/CT imaging results with biochemical progression at the last follow-up.

RESULTS

Fifty-eight patients (30 in surgery and 28 in radiotherapy groups) met the inclusion criteria. A total of 87 PSMA-positive lesions were detected: 16 local recurrences (18.4%), 54 regional lymph nodes (62.1%), 6 distant lymph nodes (6,8%), and 11 osseous lesions (12.7%). A total of 85.7% (24 of 28) and 70.0% (21 of 30) of patients showed a ≥ 50% decrease in prostate-specific antigen (PSA) levels after RT and surgery, respectively. At a median follow-up time of 21 months (range, 6-32 months), the median biochemical progression-free survival was 19 months (range, 4 to 23 months) in the radiotherapy group, as compared with 16.5 months (range, 4 to 28 months) in the surgery group. On multivariate Cox regression analysis, the number of PSMA positive lesions (2-5 lesions compared to one lesion), and the anatomic location of the detected lesions (distant metastasis vs. local relapse and pelvic nodal relapse) significantly correlated with biochemical progression at the last follow-up, whereas other clinical, tumor-specific, and imaging parameters did not.

CONCLUSIONS

This study suggests that RT or surgery based on [¹⁸F]DCFPyL PET/CT are associated with high PSA response rates. The number and site of lesions detected on the PSMA PET/CT were predictive of biochemical progression on follow-up. Further studies are needed to assess the impact of targeting these sites on patient relevant outcomes.

TRIAL REGISTRATION

Registered September 14, 2016; NCT02899312; https://clinicaltrials.gov/ct2/show/NCT02899312.

Yttrium-90 Radiation Segmentectomy in Oligometastatic Secondary Hepatic Malignancies

PURPOSE

To evaluate the safety and efficacy of yttrium-90 (⁹⁰Y) radiation segmentectomy (RS) in the treatment of oligometastatic secondary hepatic malignancies.

MATERIALS AND METHODS

This institutional review board-approved retrospective study evaluated 16 patients with oligometastatic secondary hepatic malignancies who were treated with RS. The median patient age was 61.9 years (range, 38.6-85.7 years). Of the 16 patients, 11 (68.8%) presented with solitary lesions. The median index tumor size was 3.1 cm (95% CI, 2.3-3.9). Primary outcomes were evaluation of clinical and biochemical toxicities using National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.0, and imaging response using Response Evaluation Criteria in Solid Tumors, version 1.1. Secondary outcomes were time to progression (TTP) and overall survival (OS) as estimated by the Kaplan-Meier method.

RESULTS

Clinical Grade 3 toxicities were limited to 1 (6.7%) patient who experienced fatigue, abdominal pain, nausea, and vomiting. Biochemical Grade 3 toxicities occurred in 1 (6.7%) patient who experienced lymphopenia. No Grade 4 clinical or biochemical toxicities were identified. Disease control was achieved in 14 (93.3%) of 15 patients. The median TTP of the treated tumor was 72.9 months (95% CI, 11.2 to no estimate). The median OS was 60.9 months (95% CI, 24.7 to no estimate).

CONCLUSIONS

⁹⁰Y RS displayed an excellent safety profile and was effective in achieving a high disease control rate in the treatment of oligometastatic secondary hepatic malignancies.

Evaluation of HyperArc™ using film and portal dosimetry quality assurance

HyperArc™ is a stereotactic radiotherapy modality designed for targeting multiple brain metastases using a single isocenter with multiple non-coplanar arcs. This study aimed to assess the efficacy of two patient-specific quality assurance methods, film and the Varian Portal Dosimetry System with Varian's HyperArc™ technique and raise important considerations in the customisation of patient-specific quality assurance to accommodate HyperArc™ delivery. Assessment criteria included gamma analysis and mean dose at full width half maximum. The minimum metastasis size, maximum off-axis distance and suitable energy were identified and validated. Patient-specific quality assurance procedures were applied to a range of clinically relevant brain metastasis plans. Initial investigation into energy selection showed no significant differences in gamma pass rates using 6MV, 6MV FFF, or 10MV FFF for metastasis sizes greater than 15 mm diameter at the isocenter. Gamma pass rates (2%/2mm) for 15 mm metastases at the isocenter for all energies were greater than 96.0% for portal dosimetry and greater than 98.7% for film. Fields of size 15 mm placed at various distances (10-70 mm) from the isocenter resulted in a maximum mean dose difference of 1.5% between film and planned. Clinically relevant plans resulted in a maximum mean dose difference for selected metastases of 1.0% between film and plan and a maximum point dose difference of 2.9% between portal dose and plan. Portal dose image prediction was a quick and convenient quality assurance tool for metastases larger than 15 mm near the isocenter but provided diminished geometrical relevance for off-axis metastases. Film QA required exacting procedures but offered the ability to assess the accuracy of geometrical targeting for off-axis metastases and provided dosimetric accuracy for metastases to well below 15 mm diameter.

Characteristics of Radiopharmaceutical Uptake in Primary Tumor and Metastatic Lesions of Prostate Carcinoma: Comparison of Oligometastatic with Multimetastatic Disease

Objectives

Oligometastases may generate secondary to indolent tumor biology. In this study, we investigated whether semiquantitative measures of ¹⁸F-fluorodeoxyglucose (FDG) and gallium-68 (⁶⁸Ga) prostate-specific membrane antigen (PSMA) uptake of metastatic lesions and prostatic sites are different between oligometastatic (OM) and multimetastatic (MM) disease of prostate carcinoma (PC).

Methods

Patients with PC, who underwent positron emission tomography/computed tomography (PET/CT) from October 2012 to February 2020 were retrospectively reviewed. Patients, whose reports were consistent with metastatic diseases were selected. Patients classified as with MM or OM disease. Maximum standardized uptake values (SUV_max) were calculated from metastatic lesions and the prostatic site. The median of the SUV_max results between patients with OM and MM disease were compared.

Results

A totally 145 patients with a mean age of 71.46±9.26, were evaluated. In 59 of 145 patients, ¹⁸F-FDG PET/CT was performed;86 patients had gone through ⁶⁸Ga PSMA PET/CT. Thirty-seven of 145 patients were OM, whereas 108 patients were MM. The median of the SUV_max of metastatic lesions in patients with OM and MM disease in the ¹⁸F-FDG group were 5.60 and 9.51, respectively. The results of the calculated median SUV_max values in OM and MM disease in the Ga-68 PSMA group were 13.44 and 29.84, respectively. A significant difference was observed in the median SUV_max results of metastatic lesions between OM and MM disease (p<0.05). Median values of SUV_max calculated from the prostatic site in OM and MM disease were 7.83 and 12.29 respectively in ¹⁸F-FDG; 26.23 and 26.74 in the ⁶⁸Ga PSMA group. No significant difference was found in the SUV_max results of the prostatic site between OM and MM disease (p>0.05).

Conclusion

SUV_max results of metastatic lesions are significantly higher in patients with MM than in patients with OM disease in patients with PC, which may be secondary to their different biological contents in terms of aggressiveness.

Prognostic factors in endometrial cancer patients with bone metastasis

OBJECTIVES

This study aims to examine the pattern and prognosis of osseous involvement and the role of orthopedic surgery in patients with endometrial cancer (EC) and to evaluate the quality of life, local tumor control, and survival of patients.

PATIENTS AND METHODS

Between January 2011 and December 2018, a total of 14 patients (median age: 60.5 years; range, 55 to 73 years) who were surgically treated for osseous metastasis of EC and followed for minimum 12 months were retrospectively analyzed. All patients were evaluated for their primary malignancy, characteristics of bone metastasis, and type of treatment related to musculoskeletal involvement. For evaluating the functional outcomes, the Visual Analog Scale (VAS) for pain and Eastern Cooperative Oncology Group (ECOG) performance status scale were used in the pre- and postoperative period.

RESULTS

The median follow-up was 34.5 (range, 9 to 89) months. All patients had advanced-stage disease (FIGO Stage III-IV). Four patients had solitary and 10 patients had multiple bone metastases. The mean VAS score and ECOG performance status grades improved (p<0.001 and p<0.05, respectively). The median survival after detection of bone metastasis was 61 (range, 41 to 82) months.

CONCLUSION

Endometrial cancer patients with musculoskeletal pain should be investigated for the possibility of bone metastasis to tailor a prompt treatment and to achieve a better prognosis. Appropriate surgical treatment of bone metastasis may improve both pain and performance status in carefully selected patients.

Long-term Surgical Outcomes in Oligometastatic Non-small Cell Lung Cancer: A Single-Center Study

Background

We reviewed the clinical outcomes of patients with oligometastatic (OM) non-small cell lung cancer (NSCLC) who received multimodal therapy including lung surgery.

Methods

We retrospectively analyzed 117 patients with OM NSCLC who underwent complete resection of the primary tumor from 2014 to 2017.

Results

The median follow-up duration was 2.91 years (95% confidence interval, 1.48-5.84 years). The patients included 73 men (62.4%), and 76 patients (64.9%) were under the age of 65 years. Based on histology, 97 adenocarcinomas and 14 squamous cell carcinomas were included. Biomarker analysis revealed that 53 patients tested positive for epidermal growth factor receptor, anaplastic lymphoma kinase, or ROS1 mutations, while 36 patients tested negative. Metastases were detected in the brain in 74 patients, the adrenal glands in 12 patients, bone in 5 patients, vertebrae in 4 patients, and other locations in 12 patients. Radiation therapy for organ metastasis was performed in 81 patients and surgical resection in 27 patients. The 1-year overall survival (OS) rate in these patients was 82.8%, and the 3- and 5-year OS rates were 52.6% and 37.2%, respectively. Patients with positive biomarker test results had 1-, 3-, and 5-year OS rates of 98%, 64%, and 42.7%, respectively. These patients had better OS than those with negative biomarker test results (p=0.031). Patients aged ≤65 years and those with pT1-2 cancers also showed better survival (both p=0.008).

Conclusion

Surgical resection of primary lung cancer is a viable treatment option for selected patients with OM NSCLC in the context of multimodal therapy.

Stereotactic body radiation therapy in the treatment of cancer patients with oligometastatic disease: a real world study

PURPOSE

Stereotactic body radiation therapy (SBRT) is a treatment modality with curative intent for oligometastatic cancer patients, commonly defined by a low-burden metastatic disease with 1-5 systemic metastases. Better knowledge of the clinical profile and prognostic factors in oligometastatic cancer patients could help to improve the selection of candidates who may obtain most benefits from SBRT. The objective of this study was to describe the clinical data and outcome in term of overall survival (OS) of patients with oligometastatic disease treated with SBRT over a 6-year period.

METHODS

From 2013 to 2018, 284 solid tumor cancer patients with 1-5 oligometastases underwent SBRT at a large university-affiliated oncological center in Barcelona, Spain. Variables related to the patient profile, tumor, oligometastatic disease, and treatment were evaluated.

RESULTS

A total of 327 metastatic tumors were treated with SBRT. In 65.5% of cases, metachronous tumors were diagnosed at least 1 year after diagnosis of the primary tumor. The median age of the patients was 73.9 years and 66.5% were males. The median follow-up was 37.5 months. The most common primary tumors were lung and colorectal cancer, with lung and bone as the most commonly treated metastatic sites. Ninety-three percent of patients showed a Karnofsky score (KPS) between 80 and 100. Adenocarcinoma was the most common histological type. The median overall survival was 53.4 months, with 1-, 2- and 5-year survival rates of 90.5%, 73.9% and 43.4%, respectively. Overall survival rates of breast (67.6 months, 95% CI 56.4-78.9), urological (63.3 months, 95% CI 55.8-70.8), and colorectal (50.8 months, 95% CI 44.2-57.4) tumors were higher as compared with other malignancies (20 months, 95% CI 11.2-28.8 months) (p < 0.001). Patients with Karnofsky score (KPS) of 90 and 100 showed a significantly better survival than those with impaired performance status (p = 0.001).

CONCLUSION

SBRT appears to be well tolerated and safe approach in oligometastatic patients. Patients with good performance status and with primary breast, urological and colorectal cancer have higher OS compared with other malignancies. More studies are necessary to evaluate the prognostic factors in oligometastatic disease (OMD) in order to select patients who could benefit more from this therapeutic approach.

Oligometastatic Prostate Cancer: Current Status and Future Challenges

In accordance with the spectrum theory of metastatic disease, an oligometastatic clinical state has been proposed as an intermediary step along the natural history of cancer with few (typically 1-3) metastatic lesions identifiable on imaging that may be amenable to metastasis-directed therapy. Effective therapy of oligometastatic disease is anticipated to impact cancer evolution by delaying progression and improving patient outcome at a minimal or acceptable cost of toxicity. There has been increasing recognition of oligometastatic disease in prostate cancer with the advent of new-generation imaging agents, most notably the recently approved PET radiotracers based on targeting prostate-specific membrane antigen. Early clinical trials with metastasis-directed therapy of oligometastases have provided evidence for delaying the employment of systematic therapy and improving outcome in selected patients. Despite these encouraging results, much needs to be investigated and learned about the underlying biology of the oligometastatic state along the evolutionary clinical course of prostate cancer, the identification of relevant imaging and nonimaging predictive and prognostic biomarkers, and the development of treatment strategies to optimize short-term and long-term patient outcome. We provide a review of the current status and the lingering challenges of this rapidly evolving clinical space in prostate cancer.

Perspectives on the Management of Oligometastatic Disease in Esophago-Gastric Cancer

Gastric adenocarcinoma and esophageal cancer are the fifth and seventh most common cancer types worldwide. At the time of initial diagnosis, up to 50% of esophagogastric cancers present with distant metastatic lesions and are candidates for chemotherapy. Curative surgery in this stage is still an experimental approach. Only a small number of these metastatic patients show an oligometastatic disease with no uniform definition of what oligometastatic means in gastric cancer. Nevertheless, the question remains unanswered as to whether these patients are still candidates for curative concepts. Some studies have attempted to answer this question but have not been adequately designed to address the role of a curative-intended multimodal therapy in this setting. The current FLOT-5 is designed to potentially provide a definitive answer to the question of whether curatively intended surgery plays a role or is a disadvantage in this setting.

Clinical significance of the neutrophil-to-lymphocyte ratio in oligometastatic breast cancer

Purpose

This study investigated the clinical impact of pretreatment neutrophil-to-lymphocyte ratio (NLR) on survival in patients with oligometastatic breast cancer.

Patients and methods

We collected data from 397 patients who underwent primary breast surgery from 2004 to 2015 and developed recurrence during the follow-up. We reviewed the images and clinical information and defined OMD according to the European Society for Medical Oncology advanced breast cancer guidelines. The NLR was calculated using pretreatment data of primary breast cancer. The cutoff value of the NLR was determined by receiver operating characteristic curve with Youden Index.

Results

Among 397 patients, 131 had OMD at recurrence. The low-NLR group included patients of significantly older age at primary cancer than those in the high-NLR group. A low NLR indicated a better overall survival (p = 0.023) after adjusting for relevant factors, including estrogen receptor status, surgical resection of metastatic disease, metastatic organ number, disease-free interval, and liver metastasis than did the high-NLR group. We developed prognostic models for OMD using six independent prognostic factors, including the NLR. The number of factors was associated with overall survival; patients with all six favorable factors showed a good overall survival of 90.9% at 8 years and those with four or more factors showed 70.4%.

Conclusions

The NLR was an independent prognostic factor for overall survival in OMD. The number of favorable prognostic factors was associated with overall survival. A prognostic model, including the NLR, will help identify patients with a favorable prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-022-06726-w.

Clinical application of radiotherapy in patients with oligometastatic ovarian cancer: a sharp tool to prolong the interval of systemic treatment

BACKGROUND

With the advances of radiation technology, treatment of oligometastatic disease, with limited metastatic burden, have more chances to achieve long-term local control. Here we aim to evaluate the efficacy and safety of radiotherapy (RT) in oligometastatic ovarian cancer patients.

METHODS

A retrospective analysis collecting 142 patients (189 lesions) with oligometastatic ovarian cancer were included in the study. All pateints received radiotherapy and the curative effect and response rate were evaluated by diagnostic imaging after 1-3 months of radiotherapy with RECIST. Endpoints were the rate of complete response (CR), chemotherapy-free interval (CFI), local control (LC) rate and overall survival (OS) rate. Toxicity was evaluated by the Radiation Therapy Oncology Group (RTOG). Logistic and Cox regression were used for the uni- and multivariate analysis of factors influencing survival outcomes.

RESULTS

From 2013.1.1 to 2020.12.30, a total of 142 ovarian cancer patients (189 oligometastasis lesions) were included in the analysis. Prescribed doses to an average GTV of 3.10 cm were 1.8-8 Gy/fraction, median BED (28-115, a/b = 10 Gy), 5-28 fractions. For 179 evaluable lesions, the cases of CR, partial response (PR), stable disease (SD) and progressive disease (PD) after radiotherapy were 22,39,38 and 80 respectively. The disease control rate (DCR): CR + PR + SD was 55.31%, and the objective response rate (ORR): CR + PR was 34.08%. No patient developed grade 3 or higher side effect. The median CFI was 14 months (1-99 months), and the LC rate was 69.7%, 54.3% and 40.9% in 1 year, 2 years and 5 years respectively. GTV < 3 cm before treatment, platinum sensitivity, time from the last treatment ≥ 6 months, single lesion and BED(a/b = 10 Gy) ≥ 60 are the factors of good LC (p < 0.05). The total OS of 1 year, 2 years and 5 years were 67.1%, 52.6% and 30.3%, respectively. Single lesion (HR 0.598, 95%CI 0.405-0.884), DCR (HR 0.640, 95% CI 0.448-0.918) and ORR(HR 0.466, 95% CI 0.308-0.707) were the significant factors influencing 5-year OS.

CONCLUSION

For patients with oligometastatic ovarian cancer, radiotherapy has high LC, long chemotherapy-free interval, and survival benefits. Subgroup analysis shows that patients with single lesion and good local treatment results have higher overall survival rate, suggesting that active treatment is also beneficial for oligometastatic ovarian cancer patients.

Oligometastatic Head and Neck Cancer: Challenges and Perspectives

Simple Summary

Oligometastasis represents a disease state and an opportunity for cure when metastases emerge. Emerging evidence supports that most head and neck cancer patients with oligometastatic disease are likely to benefit from curative intent local ablative therapy if appropriate selection criteria are applied. Biomarkers to predict development of oligometastasis, as well as to identify which patients could benefit from a radical intent approach, are under investigation. This review summarizes recent knowledge about the characteristics, investigational efforts, and evidence for local ablation regarding oligometastasis in head and neck cancer. We also describe the challenges and opportunities in patient selection and discuss the role of radiotherapy and immunotherapy combinations to enhance anti-tumor immunity.

Abstract

A minority of patients with metastatic head and neck squamous cell carcinoma (HNSCC) present with oligometastatic disease. Oligometastasis not only reflects a disease state, but might also present an opportunity for cure in the metastatic setting. Radical ablation of all oligometastatic sites may confer prolonged survival and possibly achieve cure in some patients. However, substantial debate remains about whether patients with oligometastatic disease could benefit from curative intent therapy or whether aggressive treatments expose some patients to futile toxicity. Optimal selection of patients, carefully balancing the currently known prognostic factors against the risks of toxicity is critical. Emerging evidence suggests that patients with a limited burden of disease, viral-related pharyngeal cancer, metachronous metastasis and lung-only metastasis may benefit most from this approach. Efforts are underway to identify biomarkers that can detect oligometastasis and better select patients who would derive the maximum benefit from an aggressive radical approach. The combination of radiotherapy and immunotherapy promises to enhance the anti-tumoral immune response and help overcome resistance. However, optimization of management algorithms, including patient selection, radiation dose and sequencing, will be critical in upcoming clinical trials. This review summarizes recent knowledge about the characteristics and investigational efforts regarding oligometastasis in HNSCC.

Metastasectomy or Stereotactic Body Radiation Therapy With or Without Systemic Therapy for Oligometastatic Esophagogastric Cancer

BACKGROUND

The primary goal of this study was to determine overall survival (OS) in patients who underwent local treatment (metastasectomy or stereotactic body radiotherapy [SBRT]) or systemic therapy (chemotherapy or targeted therapy) for oligometastatic esophagogastric cancer. The secondary goal was to determine prognostic factors for OS.

METHODS

Patients with synchronous or metachronous oligometastatic esophagogastric cancer who underwent local treatment or systemic therapy were included in this single-center, retrospective cohort study. Oligometastatic disease (OMD) included 1 organ or 1 extraregional lymph node station with ≤ 3 lesions. OS was determined after OMD detection. Treatment for OMD was categorized as (1) local treatment, (2) local plus systemic, (3) systemic therapy. The primary tumor was controlled after resection or definitive chemoradiotherapy.

RESULTS

In total, 85 patients were included. Treatment for OMD was local treatment (58%), local plus systemic (14%), or systemic therapy (28%). The primary tumor was controlled in 68% of patients. Most patients were diagnosed with distal esophageal cancer (61%), with adenocarcinoma histology (76%), and presented with synchronous OMD (51%). OS after local treatment was 17 months (95% confidence interval [CI] 12-40), after local plus systemic therapy 35 months (95% CI 29-NA), and after systemic therapy 16 months (95% CI 11-NA). Better OS was independently associated with local plus systemic compared with local treatment (hazard ratio [HR] 2.11, 95% CI 1.05-5.07) or systemic therapy (HR 2.28, 95% CI 1.04-6.07).

CONCLUSIONS

Local plus systemic therapy for oligometastatic esophagogastric cancer was independently associated with improved OS and better OS compared with either systemic therapy or local treatment.

MRI-guided Radiotherapy (MRgRT) for treatment of Oligometastases: Review of clinical applications and challenges

PURPOSE

Early clinical results on the application of magnetic resonance imaging (MRI) coupled with a linear accelerator to deliver MR-guided radiation therapy (MRgRT) have demonstrated feasibility for safe delivery of stereotactic body radiotherapy (SBRT) in treatment of oligometastatic disease. Here we set out to review the clinical evidence and challenges associated with MRgRT in this setting.

METHODS AND MATERIALS

We performed a systematic review of the literature pertaining to clinical experiences and trials on the use of MRgRT primarily for the treatment of oligometastatic cancers. We reviewed the opportunities and challenges associated with the use of MRgRT.

RESULTS

Benefits of MRgRT pertaining to superior soft-tissue contrast, real-time imaging and gating, and online adaptive radiotherapy facilitate safe and effective dose escalation to oligometastatic tumors while simultaneously sparing surrounding healthy tissues. Challenges concerning further need for clinical evidence and technical considerations related to planning, delivery, quality assurance (QA) of hypofractionated doses, and safety in the MRI environment must be considered.

CONCLUSIONS

The promising early indications of safety and effectiveness of MRgRT for SBRT-based treatment of oligometastatic disease in multiple treatment locations should lead to further clinical evidence to demonstrate the benefit of this technology.

Impact of the extent of lung resection on postoperative outcomes of pulmonary metastasectomy for colorectal cancer metastases: an exploratory systematic review

Background

Pulmonary metastasectomy (PM) with curative intent has become a widely accepted treatment for lung metastases from solid tumours in selected patients, with low perioperative morbidity and mortality. In particular, PM is strongly recommended in selected patients with secondary lesions from colorectal cancer (CRC), due to its excellent postoperative prognosis. Nevertheless, the impact of the extent of PM on recurrence and survival remains controversial. This review aimed at assessing differences in short- and long-term postoperative outcomes depending on the extent of lung resection for lung metastases.

Methods

A systematic literature review of studies comparing anatomical and non-anatomical resections of lung metastases was performed (Prospective Register of Systematic Reviews Registration: 254931). A literature search for articles published in English between the date of database inception and January 31, 2021 was performed in EMBASE (via Ovid), MEDLINE (via PubMed) and Cochrane CENTRAL. Retrospective studies, randomised and non-randomised controlled trials were included. The Cochrane Collaboration tool was used to determine the risk of bias for the primary outcome for included studies.

Results

Out of 432 papers, three retrospective non-randomised studies (1,342 patients) were selected for systematic reviewing. Although our search design did not exclude any primary tumour histology, all selected studies investigated surgical resection of lung metastases from CRC. Because of variations in the compared surgical approaches to pulmonary metastases, a meta-analysis proved unfeasible. There was a tendency to perform anatomical resections for larger metastases. Multivariate analyses revealed that anatomical resections were protective for recurrence-free survival (RFS), while the impact of such procedures on overall survival (OS) remained uncertain. A significantly higher incidence of resection-margin recurrences was observed in patients who underwent non-anatomical resections.

Discussion

Anatomical resections of lung metastases from CRC seem to be associated with improved RFS. However, well-constructed comparative clinical trials focusing on the extent of PM are needed.

Stratification of Oligometastatic Prostate Cancer Patients by Liquid Biopsy: Clinical Insights from a Pilot Study

We propose a pilot, prospective, translational study with the aim of identifying possible molecular markers underlying metastatic prostate cancer (PC) evolution with the use of liquid biopsy. Twenty-eight castrate sensitive, oligometastatic PC patients undergoing bone and/or nodal stereotactic body radiotherapy (SBRT) were recruited. Peripheral blood samples were collected before the commencement of SBRT, then they were processed for circulating cell free DNA (cfDNA) extraction. Deep targeted sequencing was performed using a custom gene panel. The primary endpoint was to identify differences in the molecular contribution between the oligometastatic and polymetastatic evolution of PC to same-first oligo-recurrent disease presentation. Seventy-seven mutations were detected in 25/28 cfDNA samples: ATM in 14 (50%) cases, BRCA2 11 (39%), BRCA1 6 (21%), AR 13 (46%), ETV4, and ETV6 2 (7%). SBRT failure was associated with an increased risk of harboring the BRCA1 mutation (OR 10.5) (p = 0.043). The median cfDNA concentration was 24.02 ng/mL for ATM mutation carriers vs. 40.04 ng/mL for non-carriers (p = 0.039). Real-time molecular characterization of oligometastatic PC may allow for the identification of a true oligometastatic phenotype, with a stable disease over a long time being more likely to benefit from local, curative treatments or the achievement of long-term disease control. A prospective validation of our promising findings is desirable for a better understanding of the real impact of liquid biopsy in detecting tumor aggressiveness and clonal evolution.

The Value of Radiotherapy for Advanced Non-Small Cell Lung Cancer With Oncogene Driver-Mutation

Due to the widespread use of tyrosine kinase inhibitors (TKIs), which have largely supplanted cytotoxic chemotherapy as the first-line therapeutic choice for patients with advanced non-small cell lung cancer (NSCLC) who have oncogene driver mutations, advanced NSCLC patients with oncogene driver mutations had much long median survival. However, TKIs’ long-term efficacy is harmed by resistance to them. TKIs proved to have a limited potential to permeate cerebrospinal fluid (CSF) as well. Only a small percentage of plasma levels could be found in CSF at usual doses. Therefore, TKIs monotherapy may have a limited efficacy in individuals with brain metastases. Radiation has been demonstrated to reduce TKIs resistance and disrupt the blood-brain barrier (BBB). Previous trials have shown that local irradiation for bone metastases might improve symptoms, in addition, continuous administration of TKIs combined with radiotherapy was linked with beneficial progression-free survival (PFS) and overall survival (OS) for oligometastasis or bone metastasis NSCLC with oncogene driver mutations. The above implied that radiotherapy combined with targeted therapy may have a synergistic impact in patients with advanced oncogene driver-mutated NSCLC. The objective of this article is to discuss the value of radiotherapy in the treatment of those specific individuals.

Predictive preoperative clinical score for patients with liver-only oligometastatic colorectal cancer

Background

Resection of liver metastases from colorectal cancer (CRC) in the oligometastatic stage improves survival and is a potentially curative treatment. Thus, predictive scores that reliably identify those patients who especially benefit from surgery are essential.

Patients and methods

In this multicenter analysis, 512 patients had undergone surgery for liver metastases from CRC. We investigated distinct cancer-specific risk factors that are routinely available in clinical practice and developed a predictive preoperative score using a training cohort (TC), which was thereafter tested in a validation cohort (VC).

Results

Inflammatory response to the tumor, a right-sided primary tumor, multiple liver metastases, and node-positive primary tumor were significant adverse variables for overall survival (OS). Patients were stratified in five groups according to the cumulative score given by the presence of these risk factors. Median OS for patients without risk factors was 133.8 months [95% confidence interval (CI) 81.2-not reached (nr)] in the TC and was not reached in the VC. OS decreased significantly for each subsequent group with increasing number of risk factors. Median OS was significantly shorter (P < 0.0001) for patients presenting all four risk factors: 14.3 months (95% CI 10.5 months-nr) in the TC and 16.6 months (95% CI 14.6 months-nr) in the VC.

Conclusions

Including easily obtainable variables, this preoperative score identifies oligometastatic CRC patients with prolonged survival rates that may be cured, and harbors potential to be implemented in daily clinical practice.

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We identified four variables of adverse outcome for patients treated with surgical resection of liver metastases from CRC.

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Adverse variables were inflammatory response to the tumor, multiple metastases, right-sided primary tumor, node-positive primary tumor.

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We developed a preoperative clinical score according to the number of risk factors present.

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Using easily obtainable variables, this score identified patients with oligometastatic CRC with good prognosis.

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Patients without risk factors should strongly be considered for surgical resection of their metastases.

Where Do We Stand in the Management of Oligometastatic Prostate Cancer? A Comprehensive Review

Simple Summary

Oligometastatic prostate cancer is an intermediate stage between localised and metastatic disease. Today, there are many advances in the diagnosis of this stage of the disease, with the appearance of new imaging techniques and treatments, thanks to the development of new modalities, both local and systemic therapies, the emergence of personalised medicine, and theragnostics.

Abstract

Oligometastatic prostate cancer (OMPC) is an intermediate state between localised disease and widespread metastases that includes a spectrum of disease biology and clinical behaviours. This narrative review will cover the current OMPC scenario. We conducted comprehensive English language literature research for original and review articles using the Medline database and grey literature through December 2021. OMPC is a unique clinical state with inherently more indolent tumour biology susceptible to multidisciplinary treatment (MDT). With the development of new imaging techniques, patients with OMPC are likely to be identified at an earlier stage, and the paradigm for treatment is shifting towards a more aggressive approach to treating potentially curable patients. Multimodal management is necessary to improve patient outcomes due to the combination of available therapies, such as local therapy of primary tumour, metastasis directed therapy or systemic therapy, to reduce tumour load and prevent further disease progression. Additional prospective data are needed to select patients most likely to benefit from a given therapeutic approach.

Oligometastatic disease in biochemical recurrence of prostate cancer: Prevalence on PSMA PET/CT and consecutive metastasis-directed therapy - Experience at a tertiary referral center

AIM

The aim of our study was to address the prevalence of oligometastatic recurrent prostate cancer (PCa) on PSMA-PET and the associated practice of metastasis-directed therapy (MDT). Next, we aimed to determine a PSA threshold below which most patients had local and/or oligometastatic recurrence on PSMA-PET.

METHODS

One hundred and ten consecutive patients with biochemical recurrence (BCR) after radical prostatectomy (RP) ± radiation were referred for ⁶⁸Ga-PSMA-11 or ¹⁸F-DCFPyL PET/CT. We correlated the location and number of PSMA-positive lesions against the treatment choice after imaging. Detection rates were stratified by PSA levels at the time of PET/CT. The study design was monocentric retrospective.

RESULTS

Thirty-four patients (30.9%) had a PSMA-negative scan, while 17 (15.5%) had local recurrence and 59 (53.6%) had metastatic recurrence on PSMA-PET. ROC analysis revealed a cut-off of ≤3 metastatic lesions on PSMA-PET for the steering of treatment decisions towards MDT rather than solely systemic therapy (AUC: 0.88). Defined as 3 or fewer metastatic lesions, oligometastatic recurrent PCa was found in up to 30% (33/110) of all patients. At PSA levels below 3.5 ng/ml, the rate of PSMA-positive disease that was locally confined or oligometastatic was 76% (45/59), dropping significantly to 29.4% (5/17) above this threshold (p<0.001) as polymetastatic findings became more frequent.

CONCLUSION

The detection of ≤3 oligometastases on PSMA-PET encouraged the consecutive pursuit of MDT instead of systemic therapy alone. PSMA-PET predominantly captured patients at recurrence stages amenable to localized treatment when initiated at PSA levels below 3.5 ng/ml.

Cost-effectiveness of treatment strategies for spinal metastases

PURPOSE

We analyze the cost-effectiveness of standard palliative external beam radiation (EBRT, 8 Gy in 1 fraction), stereotactic body radiation therapy (SBRT, 24 Gy in 2 fractions), and radiofrequency ablation (RFA) for painful spinal metastases. Single-fraction SBRT (delivering 24 Gy) is also assessed.

METHODS AND MATERIALS

A Markov state transition model was constructed. Key model parameters were derived from prospective clinical trial data. Strategies were compared using the incremental cost-effectiveness ratio (ICER), with effectiveness in quality-adjusted life years (QALYs) and a willingness-to-pay (WTP) threshold of $100,000 per QALY gained. Costs included both hospital and professional costs using 2020 Medicare reimbursement.

RESULTS

The base case demonstrated that 2-fraction SBRT was not cost-effective compared to single-fraction EBRT, with an ICER of $194,145/QALY gained. RFA was a dominated treatment strategy (more costly and less effective) in this model. Probabilistic sensitivity analysis demonstrated that EBRT was favored in 66% of model iterations. If median survival were improved after SBRT, two-fraction SBRT became cost-effective, with ICER of $80,394, $57,062, and $47,038 for 3, 6, and 9-month improvements in survival. Because two-fraction SBRT data reported 18% of patients with indeterminant pain response at 3 months, and two-fraction SBRT is infrequently used in clinical practice, single-fraction SBRT data was also assessed. Single-fraction SBRT delivering 24 Gy was cost-effective compared to single-fraction EBRT, with an ICER of $92,833/QALY gained.

CONCLUSIONS

For appropriately chosen patients, single-fraction SBRT is more cost-effective than conventional EBRT or RFA. Conventional EBRT remains a cost-effective treatment for patients with poor expected survival.

Recent Advances in the Management of Hormone-Sensitive Oligometastatic Prostate Cancer

After primary treatment for prostate cancer with either radical prostatectomy or radiotherapy, a significant proportion of patients are at risk of developing metastases. In recent years, a deeper understanding of the underlying biology together with improved imaging techniques and the advent of new therapeutic options including metastases-directed therapies and new drugs have revolutionized the management of low-burden metastatic disease, also known as oligometastatic state. The purpose of this narrative review is to report the recent developments in the management of hormone-sensitive oligometastatic prostate cancer patients.