[This corrects the article DOI: 10.3389/fonc.2024.1368926.].

(1) Background: Recent publications foster stereotactic body radiotherapy (SBRT) in patients with adrenal oligometastases or oligoprogression. However, local control (LC) after non-adaptive SBRT shows the potential for improvement. Online adaptive MR-guided SBRT (MRgSBRT) improves tumor coverage and organ-at-risk (OAR) sparing. Long-term results of adaptive MRgSBRT are still sparse. (2) Methods: Adaptive MRgSBRT was performed on a 0.35 T MR-Linac. LC, overall survival (OS), progression-free survival (PFS), overall response rate (ORR), and toxicity were assessed. (3) Results: 35 patients with 40 adrenal metastases were analyzed. The median gross tumor volume was 30.6 cc. The most common regimen was 10 fractions at 5 Gy. The median biologically effective dose (BED10) was 75.0 Gy. Plan adaptation was performed in 98% of all fractions. The median follow-up was 7.9 months. One local failure occurred after 16.6 months, resulting in estimated LC rates of 100% at one year and 90% at two years. ORR was 67.5%. The median OS was 22.4 months, and the median PFS was 5.1 months. No toxicity > CTCAE grade 2 occurred. (4) Conclusions: LC and ORR after adrenal adaptive MRgSBRT were excellent, even in a cohort with comparably large metastases. A BED10 of 75 Gy seems sufficient for improved LC in comparison to non-adaptive SBRT.

BACKGROUND: Interest in the oligometastatic prostate cancer (OMPC) is increasing, and various clinical studies have reported the benefits of metastasis-directed radiation therapy (MDRT) in OMPC. However, the recognition regarding the adopted definitions, methodologies of assessment, and therapeutic approaches is diverse among radiation oncologists. This study aims to evaluate the level of agreement for issues in OMPC among radiation oncologists.
METHODS: We generated 15 key questions (KQs) for OMPC relevant to definition, diagnosis, local therapies, and endpoints. Additionally, three clinical scenarios representing synchronous metastatic prostate cancer (mPC) (case 1), metachronous mPC with visceral metastasis (case 2), and metachronous mPC with castration-resistance and history of polymetastasis (case 3) were developed. The 15 KQs were adapted according to each scenario and transformed into 23 questions with 6-9 per scenario. The survey was distributed to 80 radiation oncologists throughout the Republic of Korea. Answer options with 0.0-29.9%, 30-49.9%, 50-69.9%, 70-79.9%, 80-89.9%, and 90-100% agreements were considered as no, minimal, weak, moderate, strong, and near perfect agreement, respectively.
RESULTS: Forty-five candidates voluntarily participated in this study. Among 23 questions, near perfect (n = 4), strong (n = 3), or moderate (n = 2) agreements were shown in nine. For the case recognized as OMPC with agreements of 93% (case 1), near perfect agreements on the application of definitive radiation therapy (RT) for whole metastatic lesions were achieved. While ≥70% agreements regarding optimal dose-fractionation for metastasis-directed RT (MDRT) has not been achieved, stereotactic body RT (SBRT) is favored by clinicians with higher clinical volume.
CONCLUSIONS: For the case recognized as OMPC, near perfect agreement for the application of definitive RT for whole metastatic lesions was reached. SBRT was more favored as a MDRT by clinicians with a higher clinical volume.

OBJECTIVE: We aimed to identify factors associated with the extent of brain metastases in patients with breast cancer to help distinguish brain oligometastases (1-4 brain metastases) from extensive metastases (5 or more brain metastases).
METHODS: This retrospective observational study included 100 female patients diagnosed with brain metastases from breast cancer at a single institution between January 2011 and April 2022. Patient demographics and tumor characteristics were compared between the brain oligometastases group and the extensive metastases group. Multivariable logistic regression analysis was performed to determine the independent factors, including age at initial diagnosis, initial stage, breast cancer subtype, detection time of brain metastases, and de novo or recurrent status of the metastatic disease. In a subgroup analysis of patients with brain oligometastases, demographic and tumor characteristics were compared between patients with single and two-four brain metastases.
RESULTS: Of the 100 patients, 56 had brain oligometastases, while 44 had extensive brain metastases. The multivariable logistic regression analysis revealed that only the de novo/recurrent status of metastatic breast cancer was significantly associated with the extent of brain metastasis (p = 0.023). In the subgroup analysis of 56 patients with brain oligometastases, those diagnosed at an earlier stage were more likely to have a single brain metastasis (p = 0.008).
CONCLUSIONS: Patients with de novo metastatic breast cancer are more likely to develop extensive brain metastases than those with recurrent metastatic breast cancer. This insight could influence the development of tailored approaches for monitoring and treating brain metastases, supporting the potential advantages of routine brain screening for patients newly diagnosed with stage IV breast cancer.

OBJECTIVE: Current radiotherapy guidelines rely heavily on imaging-based monitoring. Liquid biopsy monitoring promises to complement imaging by providing frequent systemic information about the tumor. In particular, cell-free DNA (cfDNA) sequencing offers a tumor-agnostic approach, which lends itself to monitoring heterogeneous cohorts of cancer patients.
METHODS: We collected plasma cfDNA from oligometastatic patients (OMD) and head-and-neck cancer patients (SCCHN) at six time points before, during, and after radiotherapy, and compared them to the plasma samples of healthy and polymetastatic volunteers. We performed low-pass (on average 7x) whole-genome sequencing on 93 plasma cfDNA samples and correlated copy number alterations and fragment length distributions to clinical and imaging findings.
RESULTS: We observed copy number alterations in 4/7 polymetastatic cancer patients, 1/7 OMD and 1/7 SCCHN patients, these patients\' imaging showed progression following radiotherapy. Using unsupervised learning, we identified cancer-specific fragment length features that showed a strong correlation with copy number-based tumor fraction estimates. In 4/4 HPV-positive SCCHN patient samples, we detected viral DNA that enabled the monitoring of very low tumor fraction samples.
CONCLUSIONS: Our results indicate that an elevated tumor fraction is associated with tumor aggressiveness and systemic tumor spread. This information may be used to adapt treatment strategies. Further, we show that by detecting specific sequences such as viral DNA, the sensitivity of detecting cancer from cell-free DNA sequencing data can be greatly increased.

UNASSIGNED: Stereotactic body radiotherapy (SBRT) is increasingly applied for pelvic lymph node recurrence. Thus far, knowledge on pelvic lymph node motion during CBCT-guided SBRT is lacking and the applied margins vary between institutions. This study evaluated pelvic lymph node motion during CBCT-guided SBRT and assessed the currently applied PTV margins of 3 and 5 mm.
UNASSIGNED: In total, 45 pelvic lymph node metastases were included. One observer delineated 45 GTVs on planning CT, 224 GTVs on pre-fraction and 216 on post-fraction CBCT. The GTV centroid coordinates were derived from all images for inter- and intrafraction motion analysis. Additionally, we assessed the influence of treatment time and lesion location on lesion motion. The expected coverage of a 3-mm and 5-mm PTV margin was assessed using the inclusiveness index for GTVs on pre- and post-fraction CBCT.
UNASSIGNED: Lymph node interfraction motion was limited to 5 mm in 96-97 % of fractions for all translational directions and intrafraction lesion motion was limited to 3 mm in 97-100 % of fractions. Para-rectal lesions (11 %) were associated with significantly larger inter- and intrafraction motion compared to other pelvic locations and treatment duration showed no correlation with lesion motion. The mean (sd) lesion inclusiveness index was 99 % (5 %) for the 5-mm PTV margin and 96 % (9 %) for the 3-mm margin.
UNASSIGNED: Pelvic lymph node motion during CBCT-guided stereotactic radiotherapy was within the widely applied PTV margin of 5 mm, providing an opportunity to reduce this margin for pelvic lymph node SBRT.

This case report describes a rare example of a solitary abdominal wall metastasis in a middle-aged endometrial cancer (EC) survivor 3 years following disease-free status. Following induction chemotherapy, she had a margin-negative surgical excision of the abdominal tumor. Surprisingly, the patient has been disease-free for more than 3 years after the operation. This emphasizes the necessity of addressing single metastasis amenable to surgical resection, as well as the need for diligent monitoring to discover recurrences sooner. Understanding rare locations of recurrence, such as the abdominal wall, is critical for optimum EC therapy and care. The data given in this article adds to the existing body of information on atypical presentations and recurrent EC therapy. Additional research is required to develop evidence-based guidance.

OBJECTIVE: Stereotactic body radiotherapy (SBRT) and/or single fraction stereotactic body radiosurgery (SRS) are effective treatment options for the treatment of oligometastatic disease of lymph nodes. Despite the encouraging local control rate, progression-free survival remains unfair due to relapses that might occur in the same district or at other sites. The recurrence pattern analysis after nodal local ablative RT (laRT) in oligometastatic patients is presented in this study.
METHODS: The pattern of failure of patients with nodal metastases who were recruited and treated with SBRT in the Destroy-1 or SRS in the Destroy-2 trials was investigated in this single-institution, retrospective analysis. The different relapsed sites following laRT were recorded.
RESULTS: Data on 190 patients who received SBRT or SRS on 269 nodal lesions were reviewed. A relapse rate of 57.2% (154 out of 269 nodal lesions) was registered. The pattern of failure was distant in 88 (57.4%) and loco-regional in 66 (42.6%) patients, respectively. The most frequent primary malignancies among patients experiencing loco-regional failure were genitourinary and gynaecological cancers. Furthermore, the predominant site of loco-regional relapse (62%) was the pelvic area. Only 26% of locoregional relapses occurred contra laterally, with 74% occurring ipsilaterally.
CONCLUSIONS: The recurrence rates after laRT for nodal disease were more frequent in distant regions compared to locoregional sites. The most common scenarios for locoregional relapse appear to be genitourinary cancer and the pelvic site. In addition, recurrences often occur in the same nodal station or in a nodal station contiguous to the irradiated nodal site.
CONCLUSIONS: Local ablative radiotherapy is an effective treatment in managing nodal oligometastasis. Despite the high local control rate, the progression free survival remains dismal with recurrences that can occur both loco-regionally or at distance. To understand the pattern of failure could aid the physicians to choose the best treatment strategy. This is the first study that reports the recurrence pattern of a significant number of nodal lesions treated with laRT.

BACKGROUND: The present study aimed to evaluate proton beam therapy (PBT) for stage IV pancreatic adenocarcinoma and its metastases and define the criteria for eligibility. Materials and methods: We retrospectively evaluated the patients who had a histopathological diagnosis of pancreatic adenocarcinoma, had progressed to stage IV, and underwent PBT for both the primary and some metastatic lesions between 2017 and 2022. PBT was performed using the passive scattering technique.
RESULTS: Sixteen patients (median age, 72 years; range, 55-85 years) were enrolled. All patients had stage IV pancreatic cancer at the initiation of PBT. The median duration from the date of stage IV diagnosis to the initiation of PBT was 5.8 (range, 0.4-13.5) months. Three patients had been diagnosed as having recurrent stage IV cancer at other institutions before their referral to our hospital because they had local recurrence and distant metastases after the resection of the primary tumor. Chemotherapy was as follows: pre-PBT, 0, 1, 2, and 3 lines in 4, 7, 4, and 1 patients, respectively; concurrent with PBT, 0 and 1 line in 11 and 5 patients, respectively; post-PBT, 0 and 1 line in 5 and 5 patients, respectively; and unknown, 6 patients. The median survival times (MSTs) from the date of stage IV diagnosis for the with or without non-irradiated active metastatic tumor were 11.4 and 20.1 months, respectively. Univariate analysis revealed that the performance status (PS) levels (p < 0.01), the carbohydrate antigen (CA) 19-9 tumor marker levels (p < 0.01), active tumors not treated with irradiation (p = 0.02), and with or without post-PBT chemotherapy (p < 0.01) were statistically significant factors. Multivariate analysis revealed that the CA 19-9 tumor marker levels (p= 0.04), the number of metastatic lesions (p = 0.049), and with or without non-irradiated active metastatic tumors (p = 0.02) were significant factors.
CONCLUSIONS: PBT is indicated when the number of metastases is limited to ≤ 4 lesions and all tumors can be irradiated within the smallest possible number of irradiation fields that can be performed within the patient\'s tolerable time, which is a subjective duration that depends on the patient\'s reaction during each session. It may be a viable treatment option for patients with oligometastatic pancreatic cancer.

UNASSIGNED: Whether surgical intervention for patients with oligometastatic recurrence can improve their post-recurrent prognosis is unclear. In this study, we introduce a novel concept of oligometastasis in post-surgical pancreatic ductal adenocarcinoma (PDAC) patients with hepatic recurrence, which we call \"oligo-like liver metastasis (OLLM).\" Patients with OLLM have better post-recurrence prognosis and could therefore be eligible for surgical intervention.
UNASSIGNED: A total of 121 PDAC patients who underwent radical resection, and who had an initial and single-organ metastasis to the liver, were analyzed. Independent prognostic factors for overall survival after recurrence (OSAR) were examined, and patients with all of these factors were defined as OLLM. The clinicopathological features and post-recurrent prognosis of OLLM patients were evaluated. In addition, a detailed analysis using the oligo-score, which was based on the prognostic factors, was performed.
UNASSIGNED: The prognostic analysis revealed that short recurrence-free interval (RFI) (<6 months), short stable disease interval (SDI) (≤3 months), and four or more recurrent tumors were independent poor prognostic factors. OLLM patients were defined as those with all three conditions: long RFI (≥6 months), long SDI (>3 months), and three or less recurrent tumors. OLLM patients had a significantly better prognosis for OSAR than non-OLLM patients (HR = 0.272, p < 0.001). Further analysis demonstrated that the OSAR of patients could be stratified using the oligo-score, which was calculated based on the prognostic factors.
UNASSIGNED: We recommend that OLLM should be used to predict which patients are most likely to experience better post-recurrent prognosis after surgery with curative intent.