Stereotactic Body Radiotherapy for Oligometastases Confined to the Para-Aortic Region: Clinical Outcomes and the Significance of Radiotherapy Field and Dose

Stereotactic Ablative Radiotherapy for Gynecological Oligometastatic and Oligoprogessive Tumors

Importance

The role of stereotactic ablative radiotherapy (SABR) for gynecologic malignant tumors has yet to be clearly defined despite recent clinical uptake.

Objective

To evaluate the outcomes of SABR in patients with oligometastatic and oligoprogressive gynecologic cancers.

Design, Setting, and Participants

In this retrospective pooled analysis, patients with oligometastatic and oligoprogressive gynecologic cancers receiving SABR at 5 institutions from Canada and the US were studied. Data were collected from January 2011 to December 2020, and data were analyzed from January to December 2023.

Exposure

Stereotactic ablative radiotherapy.

Main Outcomes and Measures

Cumulative incidence of local and distant recurrence, chemotherapy-free survival (CFS), and overall survival (OS) probabilities after SABR were calculated using Kaplan-Meier methods. Univariable and multivariable analysis was conducted using Cox regression methods.

Results

A total of 215 patients with 320 lesions meeting criteria were included in the analysis; the median (range) age at primary diagnosis was 59 (23-86) years. The median (range) follow-up from SABR was 18.5 (0.1-124.5) months. The primary site included the endometrium (n = 107), ovary (n = 64), cervix (n = 30), and vulva or vagina (n = 14). Local cumulative incidence of recurrence was 13.7% (95% CI, 9.4-18.9) and 18.5% (95% CI, 13.2-24.5) at 1 and 5 years, respectively. Distant cumulative incidence of recurrence was 48.5% (95% CI, 41.4-55.1) and 73.1% (95% CI, 66.0-79.0) at 1 and 5 years, respectively. OS was 75.7% (95% CI, 69.2-81.1) and 33.1% (95% CI, 25.3-41.1) at 1 and 5 years, respectively. The median CFS was 21.7 months (95% CI, 15.4-29.9). On multivariable analysis, local recurrence was significantly associated with nodal metastasis, lesion size, biologically effective dose, treatment indication, institution, and primary disease type. Distant progression-free survival was associated with nodal targets and lesion size. OS and CFS were significantly associated with lesion size.

Conclusions and Relevance

In this study, SABR appeared to have excellent local control with minimal toxic effects in this large patient group, and certain patients may achieve durable distant control and OS as well. It may be possible to delay time to chemotherapy in select patient subtypes and therefore reduce associated toxic effects. Prospective multicenter trials will be critical to establish which characteristics procure the greatest benefit from SABR use and to define the ideal time to implement SABR with other oncologic treatments.

Stereotactic body radiation therapy for the treatment of lymph node metastases: a retrospective mono-institutional study in a large cohort of patients

Introduction

Lymph node metastases (NMs) are a common site of tumor spread that can occur at different times of the disease. Stereotactic body radiation therapy (SBRT) can be a therapeutic option for the treatment of NMs in the setting of oligometastatic disease (OMD). The aim of this study was to evaluate as primary end points the local control (LC) and secondary end points the locoregional nodal control (LRNC), distant nodal control (DNC), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS), and concurrently to assess the predictive factors of response.

Methods

This is a retrospective study that analyzes a group of patients treated with SBRT on NMs from different primary tumors, with a of maximum five metastasis. Treated lesions were divided into four groups: oligometastatics, oligorecurrents, oligoprogressives, and oligopersistents.

Results

From 2007 to 2021, 229 NMs were treated in 174 patients with different primary tumor. The schedule most represented was 30 Gy in five fractions. The LC was obtained in 90% of NMs treated by SBRT with rates at 1, 3, and 5 years of 93%, 86%, and 86%, respectively. The LRNC was reached in 84% of cases with rates at 1, 3, and 5 years of 88%, 83%, and 77%, respectively. The DNC was obtained in 87% of cases with rates at 1, 3, and 5 years of 92%, 82%, and 78%, respectively. The DMFS was obtained in 38% of cases with rates at 1, 3, and 5 years of 57%, 40%, and 30%, respectively. The rate of PFS were 44%, 23%, and 13% at 1, 3, and 5 years, respectively. The rates at 1, 3, and 5 years of OS were 78%, 48%, and 36%, respectively.

Conclusion

SBRT is an option for the treatment of NMS, with high rates of LC, improving survival, and with a good safety and tolerance. Tumor volume, tumor burden, lesion site, and doses can be predictive factors of response; however, multi-institutional studies with a greater number of patients could be helpful to better select patients and understand the right integrations between ablative treatment and systemic therapies.

Role of stereotactic body radiotherapy in gynecologic radiation oncology

Stereotactic body radiotherapy (SBRT, also referred to as stereotactic ablative radiotherapy (SABR)) has been used in the treatment of primary and metastatic solid tumors, and increasingly so in gynecologic oncology. This review article aims to summarize the current literature describing the utility of SBRT in the primary, recurrent, and limited metastatic settings for gynecologic malignancies. The use of SBRT in both retrospective and prospective reports has been associated with adequate control of the treated site, particularly in the setting of oligometastatic disease. It is not, however, recommended as an alternative to brachytherapy for intact disease unless all efforts to use brachytherapy are exhausted. While phase I and II trials have established the relative safety and potential toxicities of SBRT, there remains a dearth of phase III randomized evidence, including the use of immunotherapy, in order to better establish the role of this technique as a method of improving more global outcomes for our patients with gynecologic cancers.

Long-term survival following definitive radiation therapy for recurrence or oligometastases in gynecological malignancies: A landmark analysis

OBJECTIVE

Radiation therapy (RT) may improve outcomes for patients with oligometastatic cancer. We sought to determine if there are long-term survivors treated with definitive RT for recurrent or oligometastatic gynecological cancer (ROMGC), and to evaluate the clinical and disease characteristics of these patients.

METHODS

We performed a landmark analysis in 48 patients with ROMGC who survived for ≥5 years following definitive RT of their metastasis. Patient characteristics were extracted from the medical record. DFS was modeled using the Kaplan-Meier method.

RESULTS

This cohort included 20 patients (42%) with ovarian cancer, 16 (33%) with endometrial cancer, 11 (23%) with cervical cancer, and one (2%) with vaginal cancer. The sites of ROMGC were the pelvic (46%), para-aortic (44%), supraclavicular (7%), mediastinal (4%), axillary (4%) lymph nodes and the lung (5.5%). Median total RT dose and fractionation were 62.1 Gy and 2.1 Gy/fraction; one patient was treated with SBRT. 32 patients (67%) received chemoradiation; these patients had higher rates of median DFS than those treated with RT alone (93 vs. 34 months, P = 0.05). At median follow-up of 11.7 years, 11 (23%) patients had progression of disease. 20 (42%) patients had died, 9 (19%) died from non-gynecologic cancer and 8 (17%) from gynecologic cancer (three were unknown). 25 (52%) patients were alive and disease-free (10 initially had endometrial cancer [63% of these patients], eight had cervical cancer [73%], six had ovarian cancer [30%], one had vaginal cancer [100%]).

CONCLUSIONS

Long-term survival is possible for patients treated with definitive RT for ROMG, however randomized data are needed to identify which patients derive the most benefit.

CARE‑compliant stereotactic radiotherapy of urothelial nodal metastases: A case report

The aim of the present study was to report the case of a 58-year-old male patient with ureteral carcinoma who underwent ureteroileostomy treatment. At 2 years following surgery, six lymph node metastases (LNMs) were detected in the patient's para-aortic and pelvic regions using ¹⁸F-labeled fluoro-2-deoxyglucose (FDG) positron emission tomography (PET)/CT. All LNMs were treated using stereotactic body radiotherapy (SBRT; 35-40 Gy/5 fractions). At 3 months after radiotherapy, ¹⁸F-FDG-PET/CT examination revealed a complete radiological and metabolic response of all targeted treatment sites in the patient. In the 2 years following radiotherapy, another three same-dose SBRT treatments were performed on single or multiple LNMs, which were all detected in the abdomen and pelvis of the patient. Overall, a total of 11 LNMs were targeted in the patient and all exhibited complete radiological and metabolic response following treatment. The only treatment side effect reported by the patient was a slight and temporary loss of appetite. In patients with lymph node oligometastases there are two options for radiotherapy: i) Irradiation focusing on LNMs alone; and ii) prophylactic irradiation of the entire lymph node area combined with a boost on macroscopic lesions. In the patient discussed in the present study, the choice of irradiation focusing on LNMs alone made it possible to postpone systemic therapies and instead use an optimally tolerated treatment. The treatment outcome in this patient indicated that there was no radioresistance of urothelial LNMs.

Systematic review of stereotactic body radiotherapy for nodal metastases

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

Management of oligo-metastatic and oligo-recurrent cervical cancer: A pattern of care survey within the EMBRACE research network

BACKGROUND

In the metastatic or recurrent cervical cancer, systemic chemotherapy constitutes the main treatment. Though there is an increasing use of high dose external radiation and brachytherapy in the metastatic setting, no consensus exists.

METHODS

A 17-item survey was designed with additional case-based questions to explore present management of oligo-metastatic and oligo-recurrent cervix cancer within EMBRACE research group participating sites. The questions were designed to elicit prevailing practices in the management of de-novo oligo-metastasis and oligo-recurrent setting after completing the primary treatment of cervix cancer. The survey was sent electronically with two rounds of email reminders to respond over a 2-week survey period. The online survey was designed such that it was mandatory to complete all questions. The responses were recorded and results were summarized as proportions and summary statistics were generated.

RESULTS

Twenty-two centers responded to this survey. A majority (90%) of respondents reported a low incidence of de-novo oligo-metastatic cervical cancer in their practice (<5%), with a higher proportion of patients with oligo-recurrence after completing primary treatment (5-10%). All responding sites preferred to treat pelvic disease in the de-novo oligo-metastatic setting albeit with different fractionation regimens. While 68.2% of respondents recommended chemo-radiation and brachytherapy, 31.8% considered additional systemic therapy. Overall 77.3% centers recommended the use of stereotactic ablative radiation therapy to oligo-metastasis. For out-of-field nodal recurrences, 63.7% of respondents considered treating with curative intent, while 59% preferred treating in-field recurrence with palliative intent. A vast majority of the participating centers (90%) have stereotactic radiation therapy capacity and would consider a clinical trial addressing oligo-metastatic and oligo-recurrent cervical cancer.

CONCLUSION

Although contemporary practice is variable, a substantial proportion of EMBRACE centers consider high dose radiation in de-novo metastatic and oligo-recurrence settings. However, there is clear need for a joint clinical protocol and prospective studies to address the role of high dose radiation within oligo-recurrent and oligo-metastatic scenarios.

Stereotactic body radiation therapy for oligometastatic gynecologic malignancies: A systematic review

OBJECTIVE

To assess the efficacy and safety of stereotactic body radiation therapy (SBRT) for oligometastatic gynecologic malignancies.

METHOD

A comprehensive search of the PubMed, Medline, and EMBASE databases was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. "Oligometastatic" was defined as a limited number of uncontrolled/untreated metastatic lesions (typically ≤ 5), including regional nodal metastases. Primary outcomes were response rate (complete response or partial response), local control of oligometastatic lesions, and toxicity.

RESULTS

Of 716 screened records, 17 studies (13 full length articles, 4 conference abstracts) were selected and analyzed as 16 unique studies. A total of 667 patients were treated with ~1071 metastatic lesions identified. Primary sites included ovarian (57.6%), cervical (27.1%), uterine (11.1%), vaginal (0.4%), vulvar (0.3%), and other/unspecified (3.4%). Most patients (65.4%) presented with a single metastatic lesion. Metastatic lesion sites included the abdomen (44.2%), pelvis (18.8%), thorax (15.5%), neck (4.6%), central nervous system (4.3%), bone (1.6%), and other/unspecified (11%). Of the lesions, 64% were nodal. Response rate (among 8 studies) ranged from 49% to 97%, with 7/8 studies reporting > 75% response rate. Local control ranged from 71% to 100%, with 14/16 studies reporting ≥ 80% local control. No grade ≥ 3 toxicities were observed in 9/16 (56%) studies. Median progression-free survival (PFS) (among 10 studies) ranged from 3.3 months to 21.7 months. Disease progression most commonly occurred outside of the SBRT radiation field (79% to 100% of failures).

CONCLUSIONS

SBRT for oligometastatic gynecologic malignancies is associated with favorable response and local control rates but a high rate of out-of-field progression and heterogeneous PFS. Additional study into rational combinations of SBRT and systemic therapy appears warranted to further improve patient outcomes.

Survey of current practices from an international task force for gynecological stereotactic ablative radiotherapy

Background

Stereotactic Ablative Radiotherapy (SABR) is an effective treatment that improves local control for many tumours. However, the role of SABR in gynecological cancers (GYN) has not been well-established. We hypothesize that there exists considerable variation in GYN-SABR practice and technique. The goal of this study is to describe clinical and technical factors in utilization of GYN-SABR among 11 experienced radiation oncologists.

Materials and methods

A 63 question survey on GYN-SABR was sent to 11 radiation oncologists (5 countries) who have published original research, conducted trials or have an established program at their institutions. Responses were combined and analyzed at a central institution.

Results

Most respondents indicated that salvage therapy (non-irradiated or re-irradiated field) for nodal (81%) and primary recurrent disease (91%) could be considered standard options for SABR in the setting of inability to administer brachytherapy. All other indications should be considered on clinical trials. Most would not offer SABR as a boost in primary treatment off-trial without absolute contraindications to brachytherapy. Multi-modality imaging is often (91%) used for planning including PET, CT contrast and MRI. There is a wide variation for OAR tolerances however small bowel is considered the dose-limiting structure for most experts (91%). Fractionation schedules range from 3 to 6 fractions for nodal/primary definitive and boost SABR.

Conclusions

Although SABR has become increasingly standard in other oncology disease sites, there remains a wide variation in both clinical and technical factors when treating GYN cancers. Nodal and recurrent disease is considered a potential indication for SABR whereas other indications should be offered on clinical trials. This study summarizes SABR practices among GYN radiation oncologists while further studies are needed to establish consensus guidelines for GYN-SABR treatment.

Feasibility of split-course stereotactic ablative radiotherapy for oligometastases

Background

There is growing interest in the use of stereotactic ablative radiotherapy (SABR) for oligometastases. However, extreme caution should be exercised in treating tumors closely located to organs at risk (OARs) with SABR. To reduce complications, we have applied split-course SABR to oligometastases closely located to OARs or to those being retreated with radiotherapy.

Methods

We retrospectively reviewed the records of patients with oligometastases who were treated with planned split-course SABR between January 2012 and December 2016.

Results

A total of 23 patients with 29 oligometastatic lesions were enrolled. The primary diagnoses were bone and soft tissue cancers in 13 lesions, liver cancers in 12 lesions, and colorectal cancers in four lesions. The median tumor volume was 78 cm3 (range, 4-1781 cm3). The lesions were treated with 1-3 fractions in the first stage of SABR (first SABR), and one or two fractions in the second stage of SABR (second SABR). The time interval between the two stages was about 4 weeks. A partial response was noted in 16 lesions (55%) after the first SABR, and practical reductions in the doses to OARs were observed in the second SABR compared with the first SABR. The 1-, 2- and 3-year local control rates were 92%, 65% and 43%, respectively. No Grade 4 or 5 toxicities were observed during or after treatment.

Conclusion

Split-course SABR appeared to be feasible for the treatment of oligometastases closely located to OARs.

An atlas to aid delineation of para-aortic lymph node region in cervical cancer: Design and validation of contouring guidelines

INTRODUCTION

Previous studies have investigated the anatomical distribution of para-aortic lymph nodes (PAN) in patients with cervical cancer. However, an atlas for accurate clinical target volume (CTV) delineation has yet to be defined. The purpose of this study was to design and verify a computerized tomography (CT) atlas to provide guidance for contouring the PAN CTV in patients with cervical cancer.

MATERIALS AND METHODS

This prospective study included 21 cervical cancer patients (design cohort) with 39 pathological PAN identified on (18)F-FDG PET-CT. PAN [left lateral para-aortic (LLPA), aorto-caval (AC), right para-caval (RPC) nodes] were delineated on CT simulation scans. Measurements were taken from the volumetric centre of the nodes to the edge of aorta and inferior vena-cava (IVC). Initially the aorta and IVC were expanded by the mean distance to the lymph node centre to create a CTV. Expansion margins were then increased asymmetrically until the CTV resulted in a clinically acceptable number of PAN included. The CTV was validated on a further 10 patients (validation cohort) with 29 PAN. A detailed contouring guide and accompanying visual atlas for elective PAN CTV delineation was created based on the validated margins.

RESULTS

For the design cohort (n = 21 patients, 39 PAN), the mean distance from the centre of the node to the aorta was 8 mm (range 4-17) for both LLPA (range 4-17) and AC (range 4-15) regions. Mean distance from the IVC to the centre of the nodes was 5 mm (range 4-6) in the RPC region and 6 mm (range 3-15) in the AC region. No PAN was superior to the T12-L1 interspace or the left renal vein or inferior to the L5-S1 interspace. For validation cohort (n = 10 patients, 29 PAN), mean distance from centre of the node to the aorta was 9 mm (range 5-15) in the LLPA region, 7 mm (range 6.5-14) in the AC region. Mean distance from the ICV to the centre of the nodes was 3 mm (range 2.5-4) in the RPC region and 5 mm (range 3-10) in the AC region. A CTV expansion from the aorta of 10 mm circumferentially and 15 mm laterally, and from the IVC of 8 mm anteromedially and 6 mm posterolaterally resulted in coverage of 97% (38/39) of PAN in the design cohort. On prospective validation, the described CTV included 97% (28/29) of PAN in the validation cohort.

CONCLUSION

We propose the following PAN CTV; expansion from aorta of 10 mm circumferentially except 15 mm laterally, expansion from the IVC of 8 mm anteromedial and 6 mm posterolaterally. The suggested CTV includes 97% (28/29) PAN in a validated patient cohort. A detailed guide and accompanying visual atlas is provided to aid delineation of the PAN CTV in patients with cervical cancer.

A multinational report of technical factors on stereotactic body radiotherapy for oligometastases

AIM

Oligometastatic cancer is being increasingly managed with aggressive local therapy using stereotactic body radiation therapy (SBRT). However, few guidelines exist. We summarize the results of an international survey reviewing technical factors for extracranial SBRT for oligometastatic disease to guide safe management.

MATERIALS & METHODS

Seven high-volume centers contributed. Levels of agreement were categorized as strong (6-7 common responses), moderate (4-5), low (2-3) or no agreement.

RESULTS & CONCLUSION

We present the results of a multi-national and multi-institutional survey of technical factors of SBRT for extracranial oligometastases. Key methods including target delineation, prescription doses, normal tissue constraints, imaging and set-up for safe implementation and practice of SBRT for oligometastasis have been identified. This manuscript will serve as a foundation for future clinical evaluations.

CT-guided permanent 125I seed interstitial brachytherapy for recurrent retroperitoneal lymph node metastases after external beam radiotherapy

PURPOSE

To evaluate the feasibility, efficacy, and safety of permanent (125)I seed interstitial brachytherapy reirradiation in patients with retroperitoneal lymph node recurrence under CT guidance.

METHODS AND MATERIALS

Seventeen patients with 19 retroperitoneal lymph node recurrence after external beam radiotherapy underwent CT-guided (125)I seed implant brachytherapy from October 2007 to August 2014. Treatment for all patients was preplanned using a three-dimensional radiation therapy planning system 3-5 days before brachytherapy; dosimetry verification was performed immediately after brachytherapy.

RESULTS

The actuarial D90 (dose delivered to 90% of the target volume) was 100-198 Gy (median, 126.5 Gy). In 9 patients, pain intensity decreased to mild pain 1-3 weeks after brachytherapy. Pain-free survival ranged 2-15 months (median, 5 months; 95% confidence interval [CI]: 0.1, 9.9). The overall response rate was 19 of 19 (100%). The median local control time was 15 months (95% CI: 2.3, 27.7). The 6-, 12-, and 24-month local control rate was 88.0%, 63.2%, and 42.1%, respectively. Twelve patients (70.6%) developed distant metastases and died. Two patients (11.8%) are alive with distant metastases but no evidence of local recurrence. Three patients (17.6%) are alive with no evidence of local recurrence. Median overall survival was 10 months (95% CI: 5.7, 14.3); the 1- and 2-year survival rates were 38.1% and 15.3%, respectively. No major complications related to the procedure occurred during or after brachytherapy.

CONCLUSIONS

Reirradiation with CT-guided permanent (125)I seed interstitial brachytherapy is feasible, safe, and effective as pain relief or salvage treatment for patients with recurrent retroperitoneal lymph nodes.