Tumor Control Rate Research Articles

A retrospective cohort study of stereotactic radiosurgery for vestibular schwannomas: Comparison of two age groups (75 years or older vs. 65-74 years).

Treatment outcome data of stereotactic radiosurgery (SRS) for vestibular schwannomas (VS) in patients ≥75 years (late elderly) are lacking. Approximately 39% of patients ≥75 years with VS were reported to experience severe facial palsy after surgical removal. This study compared the treatment outcomes post-SRS for VS between patients ≥75 and 65-74 years (early elderly). Of 453 patients who underwent gamma knife SRS for VS, 156 were ≥65 years old. The late and early elderly groups comprised 35 and 121 patients, respectively. The median tumor volume was 4.4 cc, and the median radiation dose was 12.0 Gy. The median follow-up periods were 37 and 56 months in the late and early elderly groups, respectively. Tumor volume control was observed in 27 (88%) and 95 (83%) patients (P = 0.78), while additional procedures were required in 2 (6%) and 6 (6%) patients (P = 1.00) in the late and early elderly groups, respectively. At the 60th and 120th months post-SRS, the cumulative tumor control rates were 87%, 75%, 85%, and 73% (P = 0.81), while the cumulative clinical control rates were 93% and 87%, 95%, and 89% (P = 0.80), in the late and early elderly groups, respectively. In the early elderly group, two patients experienced facial pain, and one experienced facial palsy post-SRS; there were no adverse effects in the late elderly group (both P = 1.00). SRS is effective for VS and beneficial in patients ≥75 years old as it preserves the facial nerve.

Comparison of the efficacy of Cf-252 neutron intracavitary brachytherapy monotherapy with neutron intracavitary brachytherapy plus external beam radiotherapy in stage IB1 cervical cancer

ObjectiveWe aimed to compare the efficacy of californium (Cf)-252 neutron intracavitary brachytherapy (NIBT) monotherapy with NIBT plus external beam radiotherapy (ERBT) in the treatment of stage IB1 cervical cancer. MethodsFrom May 2006 to March 2014, 38 patients with stage IB1 cervical cancer with negative pelvic lymph node metastasis (NPLNM) who were treated at our hospital were enrolled in this retrospective study. A matched-pair design based on age, hemoglobin level, and tumor histology was used for the analysis. The status of all patients was assessed by the positron emission tomography - computer tomography (PET-CT) scan or the contrast enhancement pelvic CT scan. Cf-252 NIBT was administered for four times, and the total dose at point A was 42–44 Gy. ResultsThe local tumor control rate, overall survival rate, tumor-free survival rate, and late complication incidence rate in the NIBT group were 94.7%, 100%, 94.7% and 0%, respectively, which in the EBRT + NIBT group were 94.7%, 89.5%, 89.5% and 5.26%, respectively. The return of menstruation incidence rate was 36.8% in the NIBT group and 0% in the EBRT + NIBT group. ConclusionThe treatment outcomes in the NIBT group were similar to those in the EBRT + NIBT group for patients with stage IB1 cervical cancer with NPLNM, regular menstruation and at least 3 years of follow-up data. The additional advantage of NIBT monotherapy is the potential preservation of ovarian and endometrial function and hence fertility.

Commentary on relevant issues in surgical treatment of spinal metastatic tumors

The multidisciplinary treatment model led by surgery has become a comprehensive strategy and overall concept for the treatment of spinal metastatic tumors. But the surgical treatment of spinal metastatic tumors is different from primary malignant tumors of the spine. Surgery is only a part of the multidisciplinary comprehensive treatment. Therefore, the following aspects need to be evaluated comprehensively based on the survival assessment, evaluation of spinal stability damage, nerve dysfunction, and oncological characteristics of the metastatic tumors with a reasonable surgical intervention. The attention should be paid to the minimally invasive treatment of spinal metastases, progress of new radiotherapy technology, neoadjuvant chemotherapy, targeted drug therapy and other medical treatment to make a comprehensive and individualization decision which is benefit to relieve patients ' pain, reconstruct spinal stability and avoid paralysis. While improving patient survival, increasing local tumor control rate and possibly prolonging survival time, avoiding excessive surgery as much as possible.

Management of sporadic intracanalicular vestibular schwannomas: A critical review and International Stereotactic Radiosurgery Society (ISRS) practice guidelines.

The choice of an appropriate strategy for intracanalicular vestibular schwannoma (ICVS) is still debated. We conducted a systematic review and meta-analysis with the aim to compare treatment outcomes amongst management strategies (conservative surveillance (CS), microsurgical resection (MR), or stereotactic radiosurgery (SRS)) aiming to inform guideline recommendations on behalf of the International Stereotactic Radiosurgery Society (ISRS). Using PRISMA guidelines, we reviewed manuscripts published between January 1990 and October 2021 referenced in PubMed or Embase. Inclusion criteria were peer-reviewed clinical studies or case series reporting a cohort of ICVS managed with CS, MR, or SRS. Primary outcome measures included tumor control, the need for additional treatment, hearing outcomes, and posttreatment neurological deficits. These were pooled using meta-analytical techniques and compared using meta-regression with random effect. Forty studies were included (2371 patients). The weighted pooled estimates for tumor control were 96% and 65% in SRS and CS series, respectively (P < .001). Need for further treatment was reported in 1%, 2%, and 25% for SRS, MR, and CS, respectively (P = .001). Hearing preservation was reported in 67%, 68%, and 55% for SRS, MR, and CS, respectively (P = .21). Persistent facial nerve deficit was reported in 0.1% and 10% for SRS and MR series, respectively (P = .01). SRS is a noninvasive treatment with at least equivalent rates of tumor control and hearing preservation as compared to MR, with the caveat of better facial nerve preservation. As compared to CS, upfront SRS is an effective treatment in achieving tumor control with similar rates of hearing preservation.

Advances in the treatment of Adamantinomatous craniopharyngioma: How to balance tumor control and quality of life in the current environment: a narrative review.

Adamantinomatous craniopharyngioma (ACP) presents a significant challenge to neurosurgeons despite its benign histology due to its aggressive behavior and unique growth patterns. This narrative review explores the evolving landscape of ACP treatments and their efficacy, highlighting the continuous development in therapeutic approaches in recent years. Traditionally, complete resection was the primary treatment for ACP, but surgical -related morbidity have led to a shift. The invasive nature of the finger-like protrusions in the histological structure results in a higher recurrence rate for ACP compared to papillary craniopharyngioma (PCP), even after complete macroscopic resection. Given this, combining subtotal resection with adjuvant radiotherapy has shown potential for achieving similar tumor control rates and potentially positive endocrine effects. Simultaneously, adjuvant treatments (such as radiotherapy, intracystic treatment, and catheter implantation) following limited surgery offer alternative approaches for sustained disease control while minimizing morbidity and alleviating clinical symptoms. Additionally, advances in understanding the molecular pathways of ACP have paved the way for targeted drugs, showing promise for therapy. There is a diversity of treatment models for ACP, and determining the optimal approach remains a subject of ongoing debate in the present context. In order to achieve a good-term quality of life (QOL), the main goal of the cyst disappearance or reduction of surgical treatment is still the main. Additionally, there should be a greater emphasis on personalized treatment at this particular stage and the consideration of ACP as a potentially chronic neurosurgical condition. This review navigates the evolving landscape of ACP therapies, fostering ongoing discussions in this complex field.

Radiotherapy intensification for atypical and malignant meningiomas: A systematic review.

The outcomes of nonbenign (WHO Grades 2 and 3 [G2, G3]) meningiomas are suboptimal and radiotherapy (RT) dose intensification strategies have been investigated. The purpose of this review is to report on clinical practice and outcomes with particular attention to RT doses and techniques. The PICO criteria (Population, Intervention, Comparison, and Outcomes) were used to frame the research question, directed at outlining the clinical outcomes in patients with G2-3 meningiomas treated with RT. The same search strategy was run in Embase and MEDLINE and, after deduplication, returned 1 807 records. These were manually screened for relevance and 25 were included. Tumor outcomes and toxicities are not uniformly reported in the selected studies since different endpoints and time points have been used by different authors. Many risk factors for worse outcomes are described, the most common being suboptimal RT. This includes no or delayed RT, low doses, and older techniques. A positive association between RT dose and progression-free survival (PFS) has been highlighted by analyzing the studies in this review (10/25) that report the same endpoint (5y-PFS). This literature review has shown that standard practice RT leads to suboptimal tumor control rates in G2-3 meningiomas, with a significant proportion of disease recurring after a relatively short follow-up. Randomized controlled trials are needed in this setting to define the optimal RT approach. Given the increasing data to suggest a benefit of higher RT doses for high-risk meningiomas, novel RT technologies with highly conformal dose distributions are preferential to achieve optimal target coverage and organs at risk sparing.

Concomitant radiosurgical and targeted oncological treatment improves the outcome of patients with brain metastases from gastrointestinal cancer

BackgroundSo far, only limited studies exist that evaluate patients with brain metastases (BM) from GI cancer and associated primary cancers who were treated by Gamma Knife Radiosurgery (GKRS) and concomitant immunotherapy (IT) or targeted therapy (TT).MethodsSurvival after GKRS was compared to the general and specific Graded Prognostic Assessment (GPA) and Score Index for Radiosurgery (SIR). Further, the influence of age, sex, Karnofsky Performance Status Scale (KPS), extracranial metastases (ECM) status at BM diagnosis, number of BM, the Recursive Partitioning Analysis (RPA) classes, GKRS1 treatment mode and concomitant treatment with IT or TT on the survival after GKRS was analyzed. Moreover, complication rates after concomitant GKRS and mainly TT treatment are reported.ResultsMultivariate Cox regression analysis revealed IT or TT at or after the first Gamma Knife Radiosurgery (GKRS1) treatment as the only significant predictor for overall survival after GKRS1, even after adjusting for sex, KPS group, age group, number of BM at GKRS1, RPA class, ECM status at BM diagnosis and GKRS treatment mode. Concomitant treatment with IT or TT did not increase the rate of adverse radiation effects. There was no significant difference in local BM progression after GKRS between patients who received IT or TT and patients without IT or TT.ConclusionGood local tumor control rates and low rates of side effects demonstrate the safety and efficacy of GKRS in patients with BM from GI cancers. The concomitant radiosurgical and targeted oncological treatment significantly improves the survival after GKRS without increasing the rate of adverse radiation effects. To provide local tumor control, radiosurgery remains of utmost importance in modern GI BM management.

Stereotactic intensity-modulated radiotherapy for skull base meningioma using the HybridArc with Novalis STx system.

Skull base meningiomas are often difficult to remove completely with preserved nerve function and may require radiation therapy. However, the Gamma Knife is unsuitable for large tumor volume or the optic nerve, which is difficult to identify on imaging. We report the results of stereotactic radiotherapy with HybridArc using Novalis STx for skull base meningiomas. We retrospectively examined 28 patients with skull base meningioma who underwent stereotactic radiotherapy (54 Gy/30 fractions) with HybridArc. The 28 patients, nine males and 19 females, were aged 31-83 years (mean 58.4 years), and the tumor volume was 2.6-97.1 mL (mean 29.7 mL). HybridArc irradiation was performed with D95 54 Gy/30 fractions for all patients with a median follow-up period of 36.0 months (range: 12-78 months). Tumor control rates at 1, 2, and 5 years after radiotherapy were 92.6%, 89.1%, and 82.8%, respectively. Only one non-atypical meningioma remained uncontrolled; thus, the tumor control rate for non-atypical meningioma at 1, 2, and 5 years was 94.1%. Tumor control rates for atypical meningioma at 1, 2, and 5 years were 85.7%, 71.4%, and 53.6%, respectively, significantly worse than for non-atypical meningiomas (P = 0.0395). Radiation injury was observed in two cases (7.1%). Visual field defects were observed in 16 patients, and diplopia in 6. Visual field and diplopia improvements were achieved in 5 and 2 patients, respectively (with overlap). Stereotactic radiotherapy (54 Gy/30 fractions) with HybridArc using Novalis STx is a safe and effective approach for relatively large skull base meningiomas.

Long-term tumor control in Koos grade IV vestibular schwannomas without the need for gross-total resection.

The modern management of patients with Koos grade IV vestibular schwannomas (VSs) aims at functional preservation and long-term tumor control. Gross-total resection (GTR) leads to optimal tumor control but frequently also results in permanent facial nerve (FN) palsy. Subtotal resection (STR) or near-total resection (NTR) followed by a wait-and-scan protocol and second-line radiation therapy (RT) in case of progressive residuals yields excellent tumor control rates with less permanent morbidity. The authors present the results of their prospective cohort of Koos grade IV VS patients who underwent less-than-total resection followed by a wait-and-scan protocol between January 2009 and December 2019 and discuss the latest evidence on this controversial subject. The cohort was followed up with annual clinical and volumetric outcome analyses after standardized MRI. Forty-eight patients were included in the analysis. The mean extent of resection was 87% (median 91%, range 45%-100%), best fitting into the definition of STR rather than NTR. In 2 cases, the proximal portion of the FN at the brainstem could not be reliably identified and monitored during the initial operation, and a second-stage resection was necessary. At 4.4 years after surgery, 81% (39/48) of the tumor residuals regressed or were stable in size. The percentage of regressive tumor residuals increased over time. Nineteen percent (9/48) of the tumor residuals displayed volumetric progression within a mean time of 35 months (median 36 months, range 14-72 months), resulting in a Kaplan-Meier estimate for progression-free survival of 79% after 4 years; higher postoperative volume showed a linear correlation with higher volumetric progression (factor 1.96, 95% CI 1.67-2.30; p < 0.001). Thirty-four of the 48 (71%) patients continue to undergo a wait-and-scan protocol. Second-line RT was performed in 14 patients (29%) within a mean time of 25 months (median 23 months, range 5-54 months), 12 (86%) of whom responded with post-RT pseudoprogression, resulting in an overall tumor control rate of 96%. At the 4.4-year follow-up from the initial resection, 92% of the patients had a good facial outcome (House-Brackmann [HB] grade I or II), 6% had a fair facial outcome (HB grade III), and 2% had a poor facial outcome (HB grades IV-VI). So far, there has been no need for salvage surgery after RT. STR followed by observation and second-line RT in cases of progression leads to good facial outcome and an excellent tumor control rate in the longer term.

Randomized Trial of FOLFOX 4 and FOLFIRI in The Treatment of Advance Colorectal Cancer

Colorectal cancer is a major global health concern, ranking third in prevalence and second in mortality. Developed countries have high incidence rates, while Pakistan is considered a low-risk region. Metastatic colorectal cancer requires targeted therapies like FOLFIRI and FOLFOX4, but their effectiveness in Pakistan is unknown. This study aims to provide insights, guide treatment decisions, and expand global understanding in the field. Objective: To compare therapeutic effects of FOLFOX4 and FOLFIRI for advanced colorectal cancer patients. Methods: The Medical Oncology Department of Jinnah Postgraduate and Medical Centre conducted a randomized controlled trial research from May 2022 to February 2023. Hundred patients of advanced colorectal cancer with a confirmed diagnosis of age 18 to 80 years, of either gender, were included. Randomly, 50 of these patients were in FOLFIRI group, and 50 in FOLFOX4 group. Both groups were compared for the treatment outcomes. Results: In the FOLFIRI group, the total response rate was 66%, whereas in the FOLFOX 4 group, it was 78%. In the FOLFIRI group, the median time to progression was 8 months, but in the FOLFOX 4 group, it was 9 months (p=0.06). In the FOLFIRI group, the total median survival time was 13 months, whereas in the FOLFOX 4 group, it was 14 months (p=0.280). Conclusions: The response rates between the two groups were similar, while FOLFOX 4 had a little higher rate of tumor control. FOLFIRI had a lower incidence of neutropenia, whereas FOLFOX 4 had a lower incidence of nausea and vomiting.

Disinhibition of T Cell Activation Via CD5 Knockout Is a Universal Strategy to Enhance Adoptive T Cell Immunotherapies

Introduction: Adoptive cell therapies (ACT) are currently revolutionizing cancer treatment. In particular, chimeric antigen receptor (CAR) T cells have demonstrated unprecedented responses against aggressive B cell malignancies with six FDA-approved products either targeting CD19 or BCMA. Other strategies for solid cancers such as T cell receptor (TCR)-redirected or tumor infiltrating T cells will soon become commercially available for melanoma and other cancers. However, despite this exciting new wave of ACT, the majority of patients will ultimately fail treatment, even in the most potent products such as CART19. One key mechanism of failure is the inability of adoptively transferred T cells to fully activate and function in the tumor bed. Thus, there is a dire need to develop effective strategies to enhance T cell activation to improve long-term responses in patients. Most of the current strategies are focused on reducing T cells' exhaustion, but another avenue is to study early T cell activation as a key step for long-term efficacy. We sought to define a broadly applicable strategy to disinhibit T cell activation by focusing on CD5, a transmembrane protein shown to negatively regulate T cell activation and proliferation through mediators such as SHP-1, CBL, and CBL-B ( Fig. 1A). We previously presented the preliminary preclinical results of CD5 knocked out (KO) anti-CD19 CAR T cells (CART19) ( Blood (2020) 136 (Supplement 1): 51-52.) and demonstrated how CD5 KO dramatically increased T cell proliferation and enhanced tumor control. Here, we translate this effect to enhance ACT in multiple models including CAR T and TCR-redirected cells. We also compared early disinhibition of T cell activation (CD5 KO) compares with the highly studied PD1 KO to assess the translational potential of this strategy. Methods and Results: We initially tested CD5 KO CAR T cells in a model of pancreatic ductal cancer adenocarcinoma (PDAC; AsPC1 cell line). We deleted CD5 in anti-mesothelin CART cells (CARTmeso) using a clinically relevant CAR construct (M5 clone) (NCT03054298). CD5 KO CARTmeso cells demonstrated enhanced tumor control (by both tumor volume and bioluminescence) and prolonged overall survival ( Fig. 1B). As observed in the CART19 model, CD5 KO T cells showed increased expansion and persistence. Furthermore, CD5 KO CARTmeso cells established prolonged immune memory, as long-term surviving mice cleared rechallenged tumors (day 74). To study the effects of CD5 KO in TCR-redirected cells, we generated TCR α constant (TRAC) KO T cells further transduced with TCR-GP100 lentivirus and compared these to cells with a double KO of both TRAC and CD5 using the GP100+ melanoma cell line DM6. TRAC CD5 KO TCR-GP100 cells showed significantly reduced GP100+ DM6 tumor growth in vitro when compared to TRAC KO TCR-GP100 cells using a live imaging system, suggesting that CD5 KO could enhance the efficacy of adoptive T cell therapies as a whole. Immune checkpoint inhibitors targeting the PD1:PDL1 axis are routinely used in the clinic. More recently, deletion of PD1 in adoptively transferred T cells has shown feasibility in the clinic and there are currently over 30 clinical trials testing PD1 KO or inhibition in CART therapy for cancer. We, therefore, aimed to compare this established strategy to reduce T cell exhaustion with the disinhibition of early CART activation with CD5 deletion. To this goal, we used a clinically relevant sgRNA to knock out PD1 from CART19 cells and compared this to Mock and CD5 KO CART19 cells against CD19+ Nalm6 B-ALL cells in vivo. In a challenge dose model, PD1 KO CART19 were unable to enhance CART efficacy, while CD5 KO CART19 cells maintained strong tumor control that correlated with increased overall survival. We further compared CD5 versus PD1 KO CARTmeso in an in vivo solid tumor model of mesothelin+ PDAC. CD5 KO CARTmeso cells demonstrated enhanced tumor control and stronger response rates as determined by tumor volume and bioluminescence imaging. This increased tumor control allowed for enhanced survival that is likely explained by the significantly increased T cell count in CD5 KO CARTmeso-treated mice. Conclusion: In conclusion, this study demonstrates that CD5 is a negative regulator and possible novel immune checkpoint for adoptive T cell immunotherapies. We show that CD5 deletion leads to the enhancement of ACT anti-tumor function in several clinically relevant models of liquid and solid tumors.

RADT-39. CYBERKNIFE: THE CURRENT STATE OF LINAC AS TREATMENT FOR VESTIBULAR SCHWANNOMAS

Abstract INTRODUCTION In the present study, we systematically review the extant literature describing CyberKnife radiosurgery (CKRS) as treatment for vestibular schwannoma (VS). We then perform pooled meta-analysis of long-term tumor control and hearing preservation rates reported across all retrospective observational series describing the efficacy of CKRS. METHODS We queried three databases to identify all primary retrospective studies reporting local tumor control and hearing preservation rates following CKRS for treatment of vestibular schwannoma. All studies returned across the three databases were subject to systematic screen according to pre-defined inclusion and exclusion criteria in a multi-step process performed by two investigators. RESULTS Following a comprehensive systematic search, a total of 15 studies comprising 2018 vestibular schwannoma patients were included. The proportion of females ranged from 30% to 60.3%, and the mean age of all 2,018 patients was 60.2 years. There were 64 patients who had neurofibromatosis type 2 (NF-2). Additionally, 309 patients had previously undergone surgical resection and/or radiosurgery for VS. In regard to CKRS treatment parameters, the marginal dose ranged from 1.9-25.78 Gy. The mean follow-up duration across the included studies was 40.0 months. Pooled rate of tumor control using the random effects model was 96% (95% CI: 95%-98%), and that of hearing preservation was 73% (95% CI: 66%-81%). The most common major complications following CKRS were trigeminal neuralgia, facial neuropathy, and hydrocephalus. CONCLUSIONS As studies on CyberKnife radiosurgery, one of the SRS modalities administered via LINAC, are far less common than studies on Gamma Knife radiosurgery for treatment of VS, more studies are needed in order to solidify the findings reported in the present meta-analysis. Although there are currently only 15 single-institution retrospective studies available in the neurosurgical literature, this study provides the most comprehensive and up-to-date analysis of highly relevant outcomes of interest in treatment of vestibular schwannoma via CyberKnife.

RADT-23. STEREOTACTIC RADIOSURGERY FOR CYSTIC VESTIBULAR SCHWANNOMA - A SYSTEMATIC REVIEW

Abstract BACKGROUND Cystic vestibular schwannoma, also historically known as cystic acoustic neuroma, is a benign intracranial tumor that can form between the pons and the cerebellum in an area known as the cerebellopontine angle. These brain tumors can be treated with radiotherapy, surgical resection, or radiosurgery. However, there is no consensus on which treatment modality is the most effective with minimal to no complications. METHODS A comprehensive review of clinical articles reporting stereotactic radiosurgery treatment for cystic vestibular schwannoma was performed. PubMed, Web of Science, Cochrane, Scopus, and Embase were independently queried and the PRISMA guidelines were followed throughout the screening process. We identified high-quality studies representing data from 186 patients. We extracted patient demographics, tumor characteristics, type of stereotactic radiosurgery, dosage, tumor control rate, and follow-up time. All the available data points were used to evaluate the effect of stereotactic radiosurgery on tumor control rate for cystic vestibular schwannoma. RESULTS A total of 186 patients underwent stereotactic radiosurgery with Gamma Knife (n = 178) and CyberKnife (n = 8). The average tumor volume was 6.47 cm3 (range 4.82 – 8.4 cm3, SD ± 1.8). The average marginal and maximum doses were 12.8 Gy (12.5 -13 Gy, SD ± 0.25) and 24.9 Gy (23.8 - 26 Gy, SD ± 1.10), respectively. The average follow-up time was 63.5 months (53.5 – 74 months, SD ± 10.2). Following stereotactic radiosurgery treatment for cystic vestibular schwannoma across all studies, almost 92% of patients had tumor control at follow-up, (95%-CI: 91.4 - 91.6). CONCLUSIONS Our systematic review revealed that stereotactic radiosurgery can provide adequate tumor control for cystic vestibular schwannoma. Therefore, stereotactic radiosurgery is an effective treatment choice in patients with cystic vestibular schwannoma.

RADT-35. STEREOTACTIC RADIOSURGERY FOR RESIDUAL, RECURRENT, AND METASTATIC HEMANGIOPERICYTOMAS: A SINGLE INSTITUTION EXPERIENCE

Abstract INTRODUCTION Hemangiopericytomas are infrequent vascular tumors originating from Zimmermann pericytes. The conventional treatment approach involves gross total resection (GTR), followed by adjuvant radiotherapy. Nevertheless, due to their tendency to infiltrate dural sinuses, high degree of vascularity, and anatomic inaccessibility, radical resection may be challenging with substantial risk of recurrence. To address this challenge, stereotactic radiosurgery (SRS) has been proposed as a promising adjuvant therapy. Objectives Our study aims to evaluate the effectiveness and safety of SRS as a potential treatment modality in patients with residual, recurrent, and metastatic hemangiopericytomas. METHODS From 1998 to 2023, 27 patients with 101 tumors underwent CyberKnife SRS at Stanford University Medical Center. The median age was 51 years at the time of treatment. The median follow-up period from SRS was 103 months (range: 6-250). All patients underwent upfront surgical resection. The median tumor volume was 1.5 cc. The median single-fraction equivalent dose (SFED) was 19 Gy. The SRS was administered at the 76% of the median isodose line (range: 64-89). RESULTS Of the 101 treated tumors, 24 (23.8%) progressed with a median time to recurrence of 30 months. At 10 years, the rates of local tumor control (LTC), overall survival (OS), and progression-free survival (PFS) were 74.3%, 80.8%, and 67%, respectively. In patients with residual lesions, the LTC rates were significantly greater when compared to those with residual or metastatic tumors. There was no significant difference between patients with residual, recurrent, and metastatic hemangiopericytomas in OS and PFS. Notably, no cases of radiation-induced adverse events were detected. CONCLUSION Our study provides the largest single-institutional retrospective series with hemangiopericytomas treated with SRS. SRS leads to excellent LTC, PFS, and OS at 10 years with negligible risk for adverse events. Therefore, it is an effective and safe management modality for patients with residual, recurrent, and metastatic hemangiopericytomas.

RADT-46. STEREOTACTIC RADIOSURGERY FOR CYSTIC AND SOLID INTRACRANIAL HEMANGIOBLASTOMAS: A SINGLE-INSTITUTION RETROSPECTIVE SERIES

Abstract INTRODUCTION Intracranial hemangioblastoma is a rare neoplasm that poses significant challenges in clinical management. Hemangioblastomas are characterized by unique radiological features into cystic or solid tumors. Out study aims to evaluate the role of SRS in the management of cystic and solid hemangioblastomas in a single institution setting. METHODS We conducted a retrospective analysis of clinical and radiological outcomes of patients with intracranial hemangioblastomas treated with CyberKnife SRS at our institute between 1998 and 2023. The follow-up data were available for 93 intracranial hemangioblastomas in 23 patients. Ten (43.5%) patients presented with 23 (25.6%) cystic hemangioblastomas, while 13 (56.5%) patients had 70 (75.3%) solid hemangioblastomas at the time of SRS treatment. The median age was 36 years and the median tumor volume accounted for 0.43 cc. The SRS was administered with the median single-fraction equivalent dose (SFED) of 20 Gy at the 77% of the median isodose line. RESULTS At a one-year follow-up, 11 initially solid hemangioblastomas developed cystic formation, resulting in a total of 34 (36.6%) cystic hemangioblastomas and 59 (63.4%) solid hemangioblastomas across 13 and 10 patients, respectively. Among these, 84.6% exhibited peritumoral edema prior to the onset of cystic formation. For 37 solid hemangioblastomas accompanied by peritumoral edema, SRS was administered before cystic transformation, remaining solid throughout the latest follow-up. Over a median follow-up period of 59 months (range: 3-260), 6 (17.6%) cystic and 13 (22%) solid hemangioblastomas progressed. The 5-year local tumor control (LTC) rate for intracranial hemangioblastomas was 84.7%, with 97% and 76.9% in cystic and solid lesions, respectively. CONCLUSION Our study illustrates the largest single-institutional long-term retrospective analysis of intracranial hemangioblastomas treated with SRS to date. Early SRS treatment at the time of edema may prevent cystic hemangioblastoma development and provides durable treatment outcomes for patients with both cystic and solid hemangioblastomas in long-term.

RADT-41. PREDICTION OF TREATMENT OUTCOME IN GAMMA KNIFE RADIOSURGERY OF BENIGN MENINGIOMAS

Abstract Objective This study aimed to assess the predictability of machine learning (ML) ensemble models for the success of Gamma Knife radiosurgery (GKRS) on non-skull base benign meningiomas. METHODS A total of 331 non-skull base benign meningiomas treated primarily with GKRS between 1997 and 2015 were retrospectively analyzed. When a tumor remained not larger than 125% of the initial volume at the last imaging follow-up and no significant change in the high signal intensity area around the tumor, it was classified as 'treatment success (TS).' Univariate correlation and multivariate logistic regression analyses were performed to identify statistically significant prognostic factors. Four ensemble algorithms were trained to predict the outcome of GKRS. The importance of features related to TS was analyzed. RESULTS The median MR imaging follow-up period was 8.6 years. The tumor control and signal change rates were 91.5% and 16.3%, respectively, and the TS rate was 77.6%. The conventional multivariate logistic regression model showed 83.7% accuracy and 37.8% specificity. The ML models had accuracies between 78.0% and 82.2% and specificities between 30.3% and 80.7%, and they were similar to those of conventional logistic regression analyses. The smaller brain volume absorbed more than 14 Gy, and the absence of signal change before GKRS was a favorable prognostic factor for TS in all models. The bagging algorithm with selected features showed the best specificity of 80.7% and the most significant AUC of 0.723. CONCLUSION A bagging ensemble algorithm with selected features had better specificity with similar accuracy than conventional multivariate logistic regression in predicting GKRS outcomes for non-skull base meningiomas.

Biomedical advances and future prospects of high-precision three-dimensional radiotherapy and four-dimensional radiotherapy.

Biomedical advances of external-beam radiotherapy (EBRT) with improvements in physical accuracy are reviewed. High-precision (±1 mm) three-dimensional radiotherapy (3DRT) can utilize respective therapeutic open doors in the tumor control probability curve and in the normal tissue complication probability curve instead of the one single therapeutic window in two-dimensional EBRT. High-precision 3DRT achieved higher tumor control and probable survival rates for patients with small peripheral lung and liver cancers. Four-dimensional radiotherapy (4DRT), which can reduce uncertainties in 3DRT due to organ motion by real-time (every 0.1-1 s) tumor-tracking and immediate (0.1-1 s) irradiation, have achieved reduced adverse effects for prostate and pancreatic tumors near the digestive tract and with similar or better tumor control. Particle beam therapy improved tumor control and probable survival for patients with large liver tumors. The clinical outcomes of locally advanced or multiple tumors located near serial-type organs can theoretically be improved further by integrating the 4DRT concept with particle beams.

RADT-40. FINAL RESULTS OF THE PROSPECTIVE PHASE 2 MARCIE TRIAL: EFFICACY AND TOXICITY OF POSTOPERATIVE BIMODAL RADIOTHERAPY WITH C12-BOOST IN PATIENTS WITH ATYPICAL MENINGIOMAS FOLLOWING SUBTOTAL RESECTION

Abstract Radiotherapy is recommended by current EANO guidelines for patients with atypical meningiomas (WHO grade 2) following subtotal resection. While meningiomas are generally considered radioresistant, novel radiotherapeutic modalities using carbon ions present an increased relative biological effectiveness (RBE) compared to photons, while reducing the radiation exposure for adjacent organs at risk by exploiting the Bragg peak. Our prospective phase 2 trial investigated bimodal radiotherapy using a carbon-ion boost in patients with atypical meningiomas following subtotal resection. A total of 33 patients were enrolled from 07/2012 until 07/2020. The study was prematurely terminated in 07/2020 after recruiting 33 of the initially planned 40 patients due to one grade 5 toxicity. Study treatment comprised a carbon ion boost (18 Gy [RBE] in 6 fractions) targeted to the macroscopic tumor in combination with photon radiotherapy (50 Gy in 25 fractions). The primary endpoint was progression-free survival, and secondary endpoints included overall survival, safety and toxicities. With a median follow-up of 42 months, the 3-year estimates of progression-free survival (PFS), local PFS and overall survival were 80.3%, 86.7% and 89.8%, respectively. Radiation-induced contrast enhancements (RICE) was encountered in 45%, particularly in cases of periventricularly-located meningiomas. Patients exhibiting (transient) RICE were either asymptomatic (40%) or presented immediate improvement (47%) after the administration of corticosteroids or/and bevacizumab. Treatment-associated complications were encountered in 2 patients with radiation necrosis: 1 patient died due to postoperative complications in an external center after resection of radiation necrosis, and the other received an aggregated 21 cycles of bevacizumab. As a result, the study was prematurely terminated. Post-hoc integrated molecular-morphologic scoring identified patients at risk of tumor progression. Study treatment may be considered for selected patients with molecular high-risk meningiomas to achieve high tumor control rates. Patients’ risk to develop radiation-induced side effects depends on the location of the treatment volume.

NCOG-27. LONG-TERM OUTCOMES OF GAMMA KNIFE RADIOSURGERY FOR GROWING MENINGIOMA

Abstract Gamma knife radiosurgery (GKRS) has become an effective treatment modality for intracranial meningioma. However, the role of GKRS in managing growing meinigoma during follow-up remains uncertain. This study aims to investigate the long-term outcome after GKRS treatment on meningioma for growing meningioma at follow-up. A retrospective analysis was conducted on patients who underwent GKRS as primary treatment for growing meingiomas between 2004 and 2021. Growing meningioma was defined as a &amp;gt;10% increase in volume compared to the previous imaging. Fifty-nine patients who received GKRS as initial treatment were included in this study with minimum follow-up period of 12 months. Patient clinical-radiological data, tumor characteristics and procedural details were analyzed. Tumor progression and regression were defined as a &amp;gt;10% increase or decrease in volume, respectively, compared to pre-GKRS image. Tumor volumes within ±10% of pre-GKRS volume were considered stable. At a median follow-up of 41 months (range 15-197 months), tumor volume was unchanged in 16 patients (27.1%), decreased in 41 patients (69.5%), and increased in 2 patients (3.4%). In multivariate analysis, growth rate was significantly associated with tumor progression (hazard ratio [HR]=2.059, 95% confidence interval [CI]=1.028-4.123, p=0.042). Eleven patients (18.6%) experienced new or worsening symptoms. In multivariate analysis, factors predicting new or worsening neurological function were preexisting symptoms (HR=7.159, 95% CI=1.468-34.911, p=0.015) and tumor calcification (HR=11.921, 95% CI=2.400-59.202), p=0.002), and pre-existing peritumoral edema (HR=9.751, 95% CI=1.666-57.058, p=0.012). GKRS demonstrates a high tumor control rate as well as an acceptable complication rate in growing meningioma. Effective tumor control is more likely in patients with slow-growing tumor.

Percutaneous image-guided ablation for hepatic metastases.

The presence of hepatic metastases indicates advanced disease and is associated with significant morbidity and mortality, especially when the hepatic disease is not amenable to locoregional treatments. The primary tumour of origin, the distribution and extent of metastatic disease, the underlying liver reserve, the patient performance status and the presence of comorbidities are factors that determine whether a patient will benefit from hepatectomy or local curative-intent treatments. For patients with metastatic colorectal cancer, the most common primary cancer that spreads to the liver, several studies have demonstrated a survival benefit for patients who can be treated with hepatectomy and/or percutaneous ablation, compared to those treated with chemotherapy alone. Despite advances in surgical techniques increasing the percentage of patients eligible for surgery, most patients have unresectable disease or are poor surgical candidates. Percutaneous ablation can be used to provide local disease control and prolong survival for both surgical and non-surgical candidates. This is typically offered to patients with small hepatic metastases that can be ablated with optimal (≥10 mm) or at least adequate minimum ablation margins (≥5 mm), as high local tumour control rates can be achieved for these patients which are comparable to surgical resection. This review summarizes available evidence and outcomes following percutaneous ablation of the most frequently encountered types of hepatic metastases in the clinical practice of interventional oncology. Patient selection, technical considerations, follow-up protocols and oncologic outcomes are presented and discussed.