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

Systematic review of the efficacy of stereotactic ablative radiotherapy for oligoprogressive disease in metastatic cancer

BACKGROUND

Stereotactic Ablative Radiotherapy (SABR) for the treatment of oligometastatic disease can improve survival and delay the requirement for systemic therapy. The benefits of SABR in oligoprogressive disease are less well-defined. Here, we evaluate the available evidence investigating the efficacy of SABR in the treatment of oligoprogressive disease.

METHODS

A systematic review was carried out following PRISMA guidelines. Medline and Embase databases were searched using the terms "stereotactic radiotherapy" OR "SABR" OR "Stereotactic Ablative Body Radiotherapy" OR "SBRT" OR "SRT" AND "oligoprogression" in May 2022, June 2023, and February 2024. Studies were excluded where: SABR was used as a radical treatment, a specific oligoprogressive cohort could not be identified, publication was as a conference abstract or where fewer than 10 patients were recruited. Studies treating only brain metastases were also excluded. The site of primary tumour, oligoprogressive sites, rates of overall survival (OS), progression free survival (PFS), local control (LC) and time to next systemic therapy were collected.

RESULTS

Thirty-three full text studies were included. These consisted of single centre and multi-institutional observational studies, case series and phase II trials. Twenty-two studies were related to a specific tumour type: 12 urological cancer (9 prostate, 3 renal cancer), 6 non-small cell lung cancer, 2 colorectal cancer, 2 breast cancer and 11 were studies covering multiple tumour sites (5 studies involving SABR to a single organ and 6 studies involving SABR to multi-organ). Median PFS was >6 months in patients with oligoprogressive prostate, non-small cell lung cancer and renal cancer patients.

CONCLUSIONS

SABR appears to have clinical benefit in oligoprogresssive prostate, lung, and renal patients. However, the optimal management of patients with oligoprogressive disease is still somewhat uncertain due to lack of prospective data. This will hopefully become clearer in the near future with the publication of further randomised trials.

Treatment Outcomes of Stereotactic Ablative Body Radiotherapy on Extra-cranial Oligometastatic and Oligoprogressive Breast Cancer: Mature Results from a Single Institution Experience

AIMS

Evidence shows stereotactic ablative body radiotherapy (SABR) is used as a non-invasive ablative therapy in the treatment of multisite oligometastatic (OM) and oligoprogressive (OP) diseases originating from metastatic breast cancer. This study aims to report the treatment outcomes and to investigate what factors that are prognostic in terms of local control, progression-free survival (PFS) and overall survival (OS) in patients receiving SABR for extracranial OM and OP diseases originating from metastatic breast cancer.

MATERIALS AND METHODS

A retrospective review on treatment records of patients with OM and OP from metastatic breast cancer who underwent SABR at a single was carried out. SABR was performed with daily image-guided radiotherapy (IGRT) using a dedicated robotic SABR machine. Local control, PFS and OS were calculated using Kaplan-Meier statistics and the post-treatment toxicity data was scored following the CTCAE v4.0 protocol. Univariate and multivariate Cox regression tests were used in the subgroup analysis of prognostic factors on PFS and OS including patients' age, types of follow-up imaging (staging CT only vs whole-body MR/PET), metastases status (OM vs OP), primary breast cancer tumour grade, hormone receptors (ER/PR/HER2) status, change of systemic treatments at SABR, number of metastases, SABR treatment sites and doses.

RESULTS

56 metastatic breast cancer patients (38 patients with OM and 18 patients with OP) were involved in this retrospective review. The median follow-up was 35.6 months (range 4.0-132.9 months). The estimated local control at 1 , 2 and 5 years were 90.9%, 88.7% and 88.7%, respectively. The estimated median PFS was 19.2 months (95%CI 10.3-28.1 months); the PFS at 1, 2 and 5 years were 63.3%, 44.4% and 33.2%. The estimated OS at 1, 2 and 5 years were 98.0%, 91.9% and 74.3%, respectively with the estimated median OS of 105.1 months (95%CI 51.5-158.7 months). The vast majority of patients tolerated the treatment well with the commonest acute side effects as grade 1 fatigue. There were no statistically significant factors found in OS regression analysis. The types of follow-up imaging, metastases status, oestrogen receptor status, and number of metastases for SABR were statistically significant factors (p < 0.05) in the multivariate Cox regression analysis on PFS.

CONCLUSION

There are limited studies published on the efficacy and post-treatment toxicities of metastatic breast cancer OM and OP SABR with adequate length of follow-up. This study confirmed that SABR was a safe, non-invasive treatment option for patients with extracranial OM and OP diseases originated from primary breast cancer in terms of the acceptable post-treatment toxicities.

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.

Local Control Following Stereotactic Body Radiation Therapy for Liver Oligometastases: Lessons from a Quarter Century

The utilization of stereotactic body radiation therapy for the treatment of liver metastasis has been widely studied and has demonstrated favorable local control outcomes. However, several predictive factors play a crucial role in the efficacy of stereotactic body radiation therapy, such as the number and size (volume) of metastatic liver lesions, the primary tumor site (histology), molecular biomarkers (e.g., KRAS and TP53 mutation), the use of systemic therapy prior to SBRT, the radiation dose, and the use of advanced technology and organ motion management during SBRT. These prognostic factors need to be considered when clinical trials are designed to evaluate the efficacy of SBRT for liver metastases.

Local treatment in oligometastasis from breast cancer: an overview

Oligometastasic breast cancer (OMBC) consists of breast cancer patient with a limited number of systemic metastases (≤ 5), all of them candidates for local ablative treatment with the intention of achieving long-term control of the metastasis and, eventually, an increase in survival The first consensus for the management of patients with oligometastatic breast cancer (OMBC) was published in 2007, establishing that a more aggressive multidisciplinary strategy is recommended in order to increase the survival while maintaining a good quality of life. The current scientific evidence is based on observational studies, mainly retrospective, systematic reviews and meta-analyses, and only a randomized nonexclusive study of oligometastatic (OM) published. All trials with Stereotactic Body Radiation Therapy (SBRT) in OM cancer have shown excellent tolerance and good local control, although first trials on Lung SBRT did not prove so excellent tolerance and had some deaths due to bronchus irradiation and secondary hemoptysis. There are multiple ongoing studies researching the benefit of SBRT in oligometastatic breast cancer. Despite the lack of impact on survival seen in the NRG BR-002 Trial, SBRT probably allows the delay of the systemic treatment until progression, and so, improves the quality of life of patients. We have to wait for the results of the ongoing and future studies for clarification of the role of local treatment in OMBC.

The Effectiveness and Safety of Stereotactic Body Radiation Therapy (SBRT) in the Treatment of Oligoprogressive Breast Cancer: A Systematic Review

Stereotactic body radiotherapy (SBRT) has emerged as a technique to treat oligoprogressive sites among patients with breast cancer who are otherwise doing well on systemic therapy. This study systematically reviewed the efficacy and safety of SBRT in the setting of oligoprogressive breast cancer. A literature search was conducted in the MEDLINE database. Studies regarding SBRT and oligoprogressive breast cancer were included. Key outcomes of interest were toxicity, local control, progression, and overall survival. From 863 references, five retrospective single-center cohort studies were identified. All studies included patients with both oligometastatic and oligoprogressive disease; 112 patients with oligoprogressive breast cancer were identified across these studies. Patient age ranged from 22 to 84, with a median of 55 years of age. Most patients had hormone-receptor-positive and HER2-negative disease. SBRT doses varied from 24 to 60 Gy in 1-10 fractions based on the location/size of the lesion. Forty toxicity events were reported, of which the majority (n = 25, 62.5%) were grade 1-2 events. Among 15 patients who received SBRT concurrently with a CDK4/6 inhibitor, 37.5% of patients experienced grade 3-5 toxicities. Progression-free and overall survival ranged from 17 to 57% and 62 to 91%, respectively. There are limited data on the role of SBRT in oligoprogressive breast cancer, and prospective evaluation of this strategy is awaited to inform its safety and efficacy.

Clinical Outcomes of Patients with Metastatic Breast Cancer Treated with Hypo-Fractionated Liver Radiotherapy

PURPOSE

To retrospectively review the clinical outcomes of patients with metastatic breast cancer (MBCa) following liver directed ablative intent radiotherapy (RT).

METHODS

Demographics, disease and treatment characteristics of patients with MBCa who received liver metastasis (LM) directed ablative RT between 2004-2020 were analysed. The primary outcome was local control (LC), secondary outcomes included overall survival (OS) and progression-free survival (PFS) analyzed by univariate (UVA) and multi-variable analysis (MVA).

RESULTS

Thirty MBCa patients with 50 LM treated with 5-10 fraction RT were identified. Median follow-up was 14.6 (range 0.9-156.2) months. Class of metastatic disease was described as induced (12 patients, 40%), repeat (15 patients, 50%) and de novo (three patients, 10%). Median size of treated LM was 3.1 cm (range 1-8.8 cm) and median biologically effective dose delivered was 122 (Q1-Q3; 98-174) Gy₃. One-year LC rate was 100%. One year and two-year survival was 89% and 63%, respectively, with size of treated LM predictive of OS (HR 1.35, p = 0.023) on UVA. Patients with induced OMD had a significantly higher rate of progression (HR 4.77, p = 0.01) on UVA, trending to significance on MVA (HR 3.23, p = 0.051).

CONCLUSIONS

Hypo-fractionated ablative liver RT in patients with MBCa provides safe, tolerable treatment with excellent LC.

Systemic treatment with or without ablative therapies in oligometastatic breast cancer: A single institution analysis of patient outcomes

PURPOSE

Local ablative treatment (LAT) is increasingly combined with systemic therapy in oligometastatic breast cancer (OMBC), without a high-level evidence to support this strategy. We evaluated the addition of LAT to systemic treatment in terms of progression-free survival (PFS) and overall survival (OS). Secondary endpoints were local control (LC) and toxicity. We sought to identify prognostic factors associated with longer OS and PFS.

METHODS AND MATERIALS

We identified consecutive patients treated between 2014 and 2018 for synchronous or metachronous OMBC (defined as ≤ 5 metastases). LAT included stereotactic body radiation therapy (SBRT) and volumetric modulated arc therapy (VMAT), surgery, cryotherapy and percutaneous radiofrequency ablation (PRA). PFS and OS were calculated, and Cox regression models analyzed for potential predictors of survival.

RESULTS

One hundred two patients were included (no-LAT, n = 62; LAT, n = 40). Sixty-four metastases received LAT. Median follow-up was 50.4 months (95% CI [44.4; 53.4]). One patient experienced grade 3 toxicity in the LAT group. Five-year PFS and OS were 34.75% (95% CI [24.42-45.26]) and 63.21% (95% CI [50.69-73.37]) respectively. Patients receiving both LAT and systemic therapy had longer PFS and OS than those with no-LAT ([HR 0.39, p = 0.002]) and ([HR 0.31, p = 0.01]). The use of LAT, HER2-positive status and hormone-receptor positivity were associated with longer PFS and OS whereas liver metastases led to worse PFS.

CONCLUSIONS

LAT was associated with improved outcomes in OMBC when added to systemic treatment, without significantly increasing toxicity. The prognostic factors identified to extend PFS and OS may help guide clinicians in selecting patients for LAT.

Emergence of MR-Linac in Radiation Oncology: Successes and Challenges of Riding on the MRgRT Bandwagon

The special issue of JCM on “Advances of MRI in Radiation Oncology” provides a unique forum for scientific literature related to MR imaging in radiation oncology. This issue covered many aspects, such as MR technology, motion management, economics, soft-tissue–air interface issues, and disease sites such as the pancreas, spine, sarcoma, prostate, head and neck, and rectum from both camps—the Unity and MRIdian systems. This paper provides additional information on the success and challenges of the two systems. A challenging aspect of this technology is low throughput and the monumental task of education and training that hinders its use for the majority of therapy centers. Additionally, the cost of this technology is too high for most institutions, and hence widespread use is still limited. This article highlights some of the difficulties and how to resolve them.

Oligometastasis in breast cancer—current status and treatment options from a radiation oncology perspective

Evidence from a few small randomized trials and retrospective cohorts mostly including various tumor entities indicates a prolongation of disease free survival (DFS) and overall survival (OS) from local ablative therapies in oligometastatic disease (OMD). However, it is still unclear which patients benefit most from this approach. We give an overview of the several aspects of stereotactic body radiotherapy (SBRT) in extracranial OMD in breast cancer from a radiation oncology perspective. A PubMed search referring to this was conducted. An attempt was made to relate the therapeutic efficacy of SBRT to various prognostic factors. Data from approximately 500 breast cancer patients treated with SBRT for OMD in mostly in small cohort studies have been published, consistently indicating high local tumor control rates and favorable progression-free (PFS) and overall survival (OS). Predictors for a good prognosis after SBRT are favorable biological subtype (hormone receptor positive, HER2 negative), solitary metastasis, bone-only metastasis, and long metastasis-free interval. However, definitive proof that SBRT in OMD breast cancer prolongs DFS or OS is lacking, since, with the exception of one small randomized trial (n = 22 in the SBRT arm), none of the cohort studies had an adequate control group. Further studies are needed to prove the benefit of SBRT in OMD breast cancer and to define adequate selection criteria. Currently, the use of local ablative SBRT should always be discussed in a multidisciplinary tumor board.

Stereotactic body radiotherapy (SBRT) and concomitant systemic therapy in oligoprogressive breast cancer patients

Breast cancer is a heterogenous disease with a deep tailoring level. Evidence is accumulating on the role of stereotactic body radiotherapy (SBRT) in the management of oligometastatic disease, however this is limited in breast cancer. The aim of the present study is to show the effectiveness of SBRT in delaying the switch to a subsequent systemic treatment in oligoprogressive breast cancer patients. Retrospective analysis from two Institutions. Primary endpoint: time to next systemic treatment (NEST). Secondary endpoints: freedom from local progression (FLP), time to the polymetastatic conversion (tPMC) and overall survival (OS). One-hundred fifty-three (153) metastases in 79 oligoprogressive breast cancer patients were treated with SBRT. Median follow-up 24 months. Median NEST 8 months. Predictive factor of NEST at the multivariate analysis (MVA) was the number of treated oligometastases (HR 1.765, 95%CI 1.322-2.355; p = < 0.01). Systemic treatment after SBRT was changed in 29 patients for polymetastatic progression and in 10 patients for oligometastatic progression < 6 months after SBRT. The 2-year FLP in the overall population was 86.7%. A biological effective dose (BED) > 70Gy₁₀ was associated with improved FLP (90% versus 74.2%). The median tPMC was 10 months. At the MVA the only factors significantly associated with tPMC were the number of oligometastases (HR 1.172, 95%CI 1.000-1.368; p = 0.03), and the local control of the treated metastases (HR 2.726, CI95% 1.108-6.706; p = 0.02). SBRT can delay the switch to a subsequent systemic treatment, however patient selection is necessary. Several predictive factors for treatment tailoring have been identified.

Stereotactic radiotherapy for soft tissue and bone sarcomas: real-world evidence

Introduction:

Selected patients with locally advanced or metastatic soft tissue and bone sarcomas (STBS) may benefit from intensive local treatment, such as stereotactic radiotherapy (SRT). This study aimed to summarize the utilization and outcomes of SRT in STBS and to identify predictive factors for progression and survival.

Materials and methods:

Consecutive patients with advanced STBS who underwent STBS in a sarcoma tertiary center were identified. We collected tumor- and treatment-related factors. Endpoints comprised time to local progression (TTLP), local progression-free survival (LPFS), time to progression, progression-free survival, and overall survival (OS). The Cox proportional-hazards model was used to identify prognostic factors.

Results:

We identified 141 patients who underwent 233 SRTs. Median follow-up was 21 months. Local and distant progression occurred after 19 and 163 SRTs, respectively. SRT for lung metastases was predictive for better TTLP and LPFS (hazard ratio, HR = 0.12, p = 0.007 and HR = 0.42, p = 0.002, respectively). Bone sarcoma (HR for TTLP = 3.18, p = 0.043; HR for LPFS = 1.99, p = 0.028) and lower administered dose (HR for TTLP = 0.98, p = 0.007; HR for LPFS = 0.99, p = 0.012) were predictive for worse TTLP and LPFS. SRT for oligometastases (HR = 0.46, p = 0.021) and lung metastases (HR = 0.55, p = 0.046) was predictive for better OS, whereas diagnosis of bone sarcoma (HR = 2.05, p = 0.029) was predictive for worse OS.

Conclusion:

SRT provides excellent local control in STBS patients without significant toxicity. Patients with oligometastatic disease, lung metastases, and soft tissue sarcomas benefit the most from SRT. The dose escalation moderately enhances local control; however, it does not translate into better survival.

Evaluation of patterns of progression on poly (ADP-ribose) polymerase inhibitor (PARPi) maintenance in ovarian cancer: a cross-sectional study

INTRODUCTION

Despite improvement in progression-free survival with poly (ADP-ribose) polymerase inhibitors (PARPi) as maintenance therapy for ovarian cancer, many patients will eventually progress on therapy. Oligoprogression is uniquely suited to considerations of local consolidation therapy in this setting, but not commonly used in ovarian cancer. In this study we evaluated the proportion of patients on PARPi maintenance who developed limited sites of disease, the location of progression, and their natural history.

METHODS

From January 2006 to December 2020, natural language processing software (DEEP6AI) was used to identify 58 patients with ovarian cancer treated with PARPi maintenance after complete or partial response after surgery and platinum-based chemotherapy at our institution. Patients were assessed for presence and location of recurrence based on radiologic findings.

RESULTS

The median patient age was 65 (IQR 57-71) years. Patients had a median of two lines of chemotherapy prior to starting PARPi. With a median follow-up of 48 (range 12-149) months, 32 (55%) patients had a recurrence on maintenance olaparib and 11 (34%) patients developed oligoprogression (≤3 sites). For the 11 patients with oligoprogression, three patients developed recurrence in one site, five in two sites, and three in three sites. The sites of oligoprogression were pelvic/periaortic nodal (27%), peritoneal (27%), liver (27%), lung/mediastinal (14%), and brain (5%). The median progression-free survival for the entire cohort was 6.0 months (95% CI 4.2 to 7.8); median overall survival was not met. There were no significant differences in overall survival (p=0.81) or progression-free survival (p=0.95) between patients with and without oligoprogression.

CONCLUSIONS

One-third of patients on PARPi maintenance experienced oligoprogression defined as limited to ≤3 sites. These patients may benefit from local consolidation therapy. A larger dataset is needed to validate these findings to assess if trials investigating local therapy for these patients is of value.

Stereotactic body radiotherapy to treat breast cancer oligometastases: A systematic review with meta-analysis

OBJECTIVES

Stereotactic ablative radiotherapy (SABR) has been reported to be an effective treatment for oligometastatic disease from different primary cancer sites. Here we assess the effectiveness and safety of SABR for oligometastatic breast cancer patients by performing a meta-analysis.

METHODS

Following PRISMA and MOOSE guidelines, a systematic review and meta-analysis was performed. Eligible studies were identified on Medline, Embase, Cochrane Library, and annual meetings proceedings from 1990 to June 2021. A meta-regression analysis was performed to assess if there was a correlation between moderator variables and outcomes, and a p-value <0.05 was considered significant.

RESULTS

Ten studies met criteria for inclusion, comprising 467 patients and 653 treated metastases. The 1- and 2-year local control rates were 97% (95% CI 95-99%), and 90% (95% CI 84-94%), respectively. Overall survival (OS) was 93% (95% CI 89-96%) at 1 year, 81% (95% CI 72-88%) at 2 years. The rate of any grade 2 or 3 toxicity was 4.1 % (95% CI 0.1-5%), and 0.7% (0-1%), respectively. In the meta-regression analysis, only prospective design (p = 0.001) and bone-only metastases (p = 0.01) were significantly associated with better OS. In the subgroup analysis, the OS at 2y were significantly different comparing HER2+, HR+/HER2(-) and triple negative breast cancer 100%, 86% and 32%, p = 0.001. For local control outcomes, hormone receptor status (p = 0.01) was significantly associated on meta-regression analysis.

CONCLUSION

SABR for oligometastatic breast cancer is safe and associated with high rates of local control. Longer follow-up of existing data and ongoing prospective trials will help further define the role of this management strategy.