High Local Control Rates Research Articles

Abstract PO2-05-11: Patient Perspectives on the Value of Stereotactic Body Radiotherapy (SBRT) in the Management of Breast Cancer: The PERSPECTIVE Study

Abstract Background: Oligometastatic disease describes limited metastases amenable to local therapy such as stereotactic body radiotherapy (SBRT). Within the UK National Health Service (NHS), SBRT is a standard of care for up to 3 metachronous sites of oligometastatic breast cancer (OMBC), offering high local control rates with low toxicity. The SABR-COMET study demonstrated improved progression-free survival (PFS) and overall survival (OS) with SBRT compared to standard of care in a number of oligometastatic cancers, including breast cancer [1]. Conversely, the NRG-002 trial results suggest no PFS or OS improvement with the addition of SBRT to standard systemic therapy in OMBC [2]. The OS data for this study are yet to mature and in the meantime the results of other prospective studies are awaited. As patients’ attitudes and perspectives govern their preferences around treatment decisions, it is vital to understand whether PFS and OS are the most important considerations for patients. This study aims to explore patients’ perspective on the role of SBRT in breast cancer management. Their views will help inform future trial endpoints and support clinicians to support patients with their decision making and expectations. Methods: We conducted an exploratory qualitative study with focus groups and individual interviews, to understand participants knowledge, views and opinions on SBRT in treating breast cancer. All patients were asked to watch an educational video about SBRT in advance of participating in the interviews. An interview guide with open-ended questions was developed. Breast cancer patients were recruited using a purposive sampling matrix based on the patients age, presence of metastatic disease and previous experience with radiotherapy. Each focus group had at least two moderators and all interviews were digitally recorded and then transcribed. The data were managed and coded using NVivo version 12 and analysed using a thematic analysis approach. Results: A total of 18 breast cancer patients participated in this study, with 7 (39%) having primary disease and 11 (61%) with metastatic disease. The study included two focus groups (group one = 5 patients; group two = 9 patients) and four individual interviews conducted between May and June 2023. The participants had a median age of 54 years (range 38-74). The majority of participants (83%) had previous experience with radiotherapy, with 4 (27%) having received SBRT previously for their OMBC. Only 2 (2%) patients who had not previously received SBRT were aware of it before participating in this study. Most of the patients (78%) were Caucasian and 72% had attained at least an undergraduate degree level of education. Throughout the study, three main themes emerged: theme 1 - participants experience with radiotherapy; theme 2 - interests and considerations regarding SBRT (including desired treatment outcomes) and theme 3 - willingness to consider SBRT in absence of a survival benefit. Extending their life was unanimously described as the most important desired outcome of SBRT, followed by quality of life. Other desired treatment outcomes expressed included reduction of tumour size, minimal collateral damage/side effects, relief of symptoms, avoidance of recurrence and increase in time to change of systemic therapy. Conclusion: In our study, while extension of life was a desired treatment outcome of SBRT for OMBC, all participants expressed willingness to consider SBRT for its potential benefits in local control and durable pain control, even in absence of a survival benefit.

Ultra‐low dose radiation therapy for primary cutaneous indolent B‐cell lymphomas

AbstractBackgroundPrimary cutaneous follicle centre lymphoma (PCFCL) and primary cutaneous marginal zone lymphoma (PCMZL) are indolent radiosensitive lymphomas, with national guidelines recommending 24 Grey (Gy) in 12 fractions, despite shorter regimens showing no difference in overall survival. Multiple studies demonstrate 4 Gy in two fractions is effective in other indolent lymphomas. Shorter regimens may result in less toxicity for patients.ObjectivesWe aim to characterise local control rates in PCFCL and PCMZL treated with radiation therapy (RT) with 4 Gy in two fractions.MethodsFrom a single institution database, we retrospectively identified all patients with PCFCL and PCMZL treated with 4 Gy in two fractions between 2011 and 2022. Prior topical or systemic treatments were permitted. T‐cell or high‐grade B‐cell cutaneous lymphomas, or those with less than 6 months follow‐up, were excluded. Primary outcomes were rates of response and local failure per lesion as determined by a radiation oncologist and oncologic dermatologist.ResultsForty‐three consecutive patients with 98 lesions treated were identified. Twenty‐four (56%) of the patients had PCMZL, and the remainder had PCFCL. Most lesions (97%) received RT with electrons. The complete response or partial response rate was 94%. Six local failures were identified (6%). With a median follow‐up of 2.75 years, 1‐, 2‐ and 3‐year local failure‐free survival were 94%, 94% and 92%, respectively. There was minimal acute toxicity, no late toxicity and no cosmesis issues. No clinical features were predictive of local failure.ConclusionsUltra‐low dose radiation was associated with high rates of local control and minimal toxicity and may reduce personal burden and financial toxicity in appropriately selected patients.

Clinicopathologic Features and Efficacy of Induction Chemotherapy in Nasopharyngeal Carcinoma: Real-World Experience

Introduction: Nasopharyngeal carcinoma (NPC) accounts for 0.01% of all carcinomas, and 70% of patients have locally advanced disease with a poor prognosis. The mainstay therapy is chemoradiotherapy (CRT), and concurrent administration of platinum-based agents and irradiation provides high local control rates. However, induction (neoadjuvant) chemotherapy (ICT) prior to CRT is recommended for large tumors with a high tumor burden at the category 1 level. For ICT, platinum-based doublet or triplet combination regimens are recommended. Selected patients with a high tumor burden at the time of diagnosis who did not receive ICT before CRT were given adjuvant (consolidation) therapy after CRT. This multicenter study aimed to share our experience in treatment of NPC and evaluate the factors associated with survival. Methods: The study included patients diagnosed with NPC who were followed and treated between 2008 and 2022. Hundred and forty-two patients from 6 centers were evaluated. The factors associated with disease-free survival (DFS) and overall survival (OS) were evaluated. Results: The median age of our patients was 51 years (IQR: 16–81 years), and the male:female ratio was 2.5:1. A majority of patients (71%) had stage 3–4 disease. They had locally advanced disease, and 48 patients (34%) received ICT. Twenty patients (14%) received adjuvant therapy. The median follow-up was 41 months (range, 2.7–175.1 months). The median DFS in NPC was 92.6 months (range, 71.9–113.3 months), with a 40th month DFS of 70.9%. The median OS was 113 months (range, 91–135 months), with a 40th month OS of 84.7%. Median DFS was 95.3 months (range, 64.2–126.4 months) in patients who received ICT before CRT, which was longer than in the CRT-only group (p = 0.6). DFS at the 40th month was 75.1% in patients treated with ICT compared to 65.1% in the CRT-only group. Median OS was 117 months (range, 92–142 months) in patients receiving ICT, which was longer than in the CRT-only group (p = 0.4). OS at the 40th month was 86.7% in patients receiving ICT but 83.6% in the CRT-only group. Conclusions: Both the objective response rate and survival were longer in patients who radiologically responded to CRT following ICT. Nonresponse to ICT is a negative predictive indicator. The role of ICT in locally advanced NPC is increasing.

Definitive results of a prospective non-randomized phase 2 study on stereotactic body radiation therapy (sbrt) for medically inoperable lung and liver oligometastases from breast cancer

Background and purposeTo report mature results for local control and survival in oligometastatic (OM) breast cancer patients treated with stereotactic body radiotherapy (SBRT) on lung and/or liver lesions in a phase II trial. MethodsThis is a prospective non-randomized phase II trial (NCT02581670) which enrolled patients from 2015 to 2021. Eligibility criteria included: age > 18 years, ECOG 0–2, diagnosis of breast cancer, maximum of 4 lung/liver lesions (with a maximum diameter < 5 cm), metastatic disease confined to the lungs and liver or extrapulmonary or extrahepatic disease stable or responding to systemic therapy. The primary end-points were local control (LC) and treatment-related toxicities. The secondary end-points included overall survival (OS), distant metastasis-free survival (DMFS), time to next systemic therapy (TTNS), poly-progression free survival (PPFS). ResultsThe study included 64 patients with a total of 90 lesions treated with SBRT. LC at 1 and 2 years was 94.9 %, 91 % at 3 years. Median local control was not reached.Median OS was 16.5 months, OS at 1, 2 and 3 years was 87.5 %, 60.9 % and 51.9 %, respectively. Median DMFS was 8.3 months, DMFS at 1, 2 and 3 years was 38.1 %, 20.6 % and 16 % respectively. At univariate analysis, local response to SBRT was found to be statistically linked with better OS, DMFS and STFS. ConclusionSBRT is a safe and valid option in oligometastatic breast cancer patients, with very high rates of local control. An optimal selection of patients is likely needed to improve survival outcomes and reduce the rate of distant progression.

SBRT-SG-01: final results of a prospective multicenter study on stereotactic body radiotherapy for liver metastases.

This study aimed to assess the efficacy and tolerability of stereotactic body radiation therapy (SBRT) for the treatment of liver metastases. Patients with up to 5 liver metastases were enrolled in this prospective multicenter study and underwent SBRT. Efficacy outcomes included in-field local control (LC), progression-free survival (PFS), and overall survival (OS). Acute and late toxicities were evaluated using CTCAE v.4.0. A total of 52 patients with 105 liver metastases were treated between 2015 and 2018. The most common primary tumor was colorectal cancer (72% of cases). Liver metastases were synchronous with the primary tumor diagnosis in 24 patients (46.2%), and 21 patients (40.4%) presented with other extrahepatic oligometastases. All patients underwent intensity-modulated radiation therapy (IMRT)/volumetric-modulated arc therapy (VMAT) with image-guided radiation therapy (IGRT) and respiratory gating, and a minimum biologically effective dose (BED10Gy) of 100Gy was delivered to all lesions. With a median follow-up of 23.1months (range: 13.4-30.9months) since liver SBRT, the median actuarial local progression-free survival (local-PFS) was not reached. The actuarial in-field LC rates were 84.9% and 78.4% at 24 and 48months, respectively. The median actuarial liver-PFS and distant-PFS were 11 and 10.8months, respectively. The actuarial median overall survival (OS) was 27.7months from SBRT and 52.5months from metastases diagnosis. Patients with lesion diameter ≤ 5cm had significantly better median liver-PFS (p = 0.006) and OS (p = 0.018). No acute or late toxicities of grade ≥ 3 were observed. This prospective multicenter study confirms that liver SBRT is an effective alternative for the treatment of liver metastases, demonstrating high rates of local control and survival while maintaining a low toxicity profile.

Stereotactic body radiotherapy in lung cancer: a contemporary review.

The treatment of early stage non-small cell lung cancer (NSCLC) has improved enormously in the last two decades. Although surgery is not the only choice, lobectomy is still the gold standard treatment type for operable patients. For inoperable patients stereotactic body radiotherapy (SBRT) should be offered, reaching very high local control and overall survival rates. With SBRT we can precisely irradiate small, well-defined lesions with high doses. To select the appropriate fractionation schedule it is important to determine the size, localization and extent of the lung tumor. The introduction of novel and further developed planning (contouring guidelines, diagnostic image application, planning systems) and delivery techniques (motion management, image guided radiotherapy) led to lower rates of side effects and more conformal target volume coverage. The purpose of this study is to summarize the current developments, randomised studies, guidelines about lung SBRT, with emphasis on the possibility of increasing local control and overall rates in "fit," operable patients as well, so SBRT would be eligible in place of surgery.

Dose-Related Visual Outcomes in the Treatment of Choroidal Melanoma with Stereotactic Radiotherapy

Introduction: Stereotactic radiotherapy (SRT) in the treatment of choroidal melanoma (CM) may be indicated if the tumour is located close to the optic nerve or is unsuitable for a radiotherapeutic plaque. It is thought that the rate of visual decline and ocular sequelae with SRT is influenced by dose and location of radiation in relation to important visual structures. This study therefore aimed to look at these prognoses with respect to localisation and dose of radiation when treatment of CM with SRT occurs. Methods: A retrospective data analysis was conducted on all patients at Dunedin Hospital (DH) from August 2001 to May 2017 who were followed up for 4 years. SRT consisted of 50 Gy divided into five fractions over 5 days to tumours, with 2-mm treatment margins. The primary outcome measure was retention of functional vision – better than hand movements (HMs) within the treated eye. Secondary outcome measures included time to non-functional vision (HM or less) in relation to location, dose and tumour thickness, the presence of radiation retinopathy, local and metastatic tumour progression, enucleation, and disease-specific mortality. Results: Seventy-five patients were identified in this study. Follow-up was incomplete in 10 patients, and 4 patients became deceased within the 4-year study period. Twenty-nine patients (48%) retained visual acuity (VA) better than HMs in the treated eye at 4 years, and thirty-two (52%) of patients did not. Calculated dose to the optic nerve and macula and proximity of the tumour to the optic nerve and macula were not statistically determinative of vision outcomes, although presenting VA was. Fifty-six per cent of patients developed radiation retinopathy involving the macula. The local progression, metastatic progression and enucleation rates were 4.6%, 6%, and 12.3%, representing 3, 4, and 8 patients, respectively. Conclusion: This study demonstrates that approximately half of patients treated with SRT can expect to maintain functional vision better than HM at 4 years. The rate of visual decline and final vision outcome are independent of location of the tumour in relation to the optic nerve and macula. While it affirms that SRT achieves high rates of local tumour control and eye retention, preservation of functional VA remains an unpredictable endpoint for individual cases and highlights the therapeutic challenge of this treatment modality.

The Value of Local Therapies in Advanced Adrenocortical Carcinoma.

International guidelines recommend local therapies (LTs) such as local thermal ablation (LTA; radiofrequency, microwave, cryoablation), transarterial (chemo)embolisation (TA(C)E), and transarterial radioembolisation (TARE) as therapeutic options for advanced adrenocortical carcinoma (ACC). However, the evidence for these recommendations is scarce. We retrospectively analysed patients receiving LTs for advanced ACC. Time to progression of the treated lesion (tTTP) was the primary endpoint. The secondary endpoints were best objective response, overall progression-free survival, overall survival, adverse events, and the establishment of predictive factors by multivariate Cox analyses. A total of 132 tumoural lesions in 66 patients were treated with LTA (n = 84), TA(C)E (n = 40), and TARE (n = 8). Complete response was achieved in 27 lesions (20.5%; all of them achieved by LTA), partial response in 27 (20.5%), and stable disease in 38 (28.8%). For the LTA group, the median tTTP was not reached, whereas it was reached 8.3 months after TA(C)E and 8.2 months after TARE (p < 0.001). The median time interval from primary diagnosis to LT was >47 months. Fewer than four prior therapies and mitotane plasma levels of >14 mg/L positively influenced the tTTP. In summary, this is one of the largest studies on LTs in advanced ACC, and it demonstrates a very high local disease control rate. Thus, it clearly supports the guideline recommendations for LTs in these patients.

Definitive single fraction spine stereotactic radiosurgery for metastatic sarcoma: Simultaneous integrated boost is associated with high tumor control and low vertebral fracture risk

IntroductionSarcoma spinal metastases (SSM) are particularly difficult to manage given their poor response rates to chemotherapy and inherent radioresistance. We evaluated outcomes in a cohort of patients with SSM uniformly treated using single-fraction simultaneous-integrated-boost (SIB) spine stereotactic radiosurgery (SSRS). Materials and MethodsA retrospective review was conducted at a single tertiary institution treated with SSRS for SSM between April 2007-April 2023. 16–24 Gy was delivered to the GTV and 16 Gy uniformly to the CTV. Kaplan-Meier analysis was conducted to assess time to progression of disease (PD) with proportionate hazards modelling used to determine hazard ratios (HR) and respective 95 % confidence intervals (CI). Results70 patients with 100 lesions underwent SSRS for SSM. Median follow-up was 19.3 months (IQR 7.7–27.8). Median age was 55 years (IQR42-63). Median GTV and CTVs were 14.5 cm3 (IQR 5–32) and 52.7 cm3 (IQR 29.5–87.5) respectively. Median GTV prescription dose and biologically equivalent dose (BED) [α/β = 10] was 24 Gy and 81.6 Gy respectively. 85 lesions received 24 Gy to the GTV. 27 % of patients had Bilsky 1b or greater disease. 16 of 100 lesions recurred representing a crude local failure rate of 16 % with a median time to failure of 10.4 months (IQR 5.7–18) in cases which failed locally. 1-year actuarial local control (LC) was 89 %. Median overall survival (OS) was 15.3 months (IQR 7.7–25) from SSRS. Every 1 Gy increase in GTV absolute minimum dose (DMin) across the range (5.8–25 Gy) was associated with a reduced risk of local failure (HR = 0.871 [95 % CI 0.782–0.97], p = 0.009). 9 % of patients developed vertebral compression fractures at a median of 13 months post SSRS (IQR 7–25). ConclusionThis study represents one of the most homogenously treated and the largest cohorts of patients with SSM treated with single-fraction SSRS. Despite inherent radioresistance, SSRS confers durable and high rates of local control in SSM without unexpected long-term toxicity rates.

Analysis of upfront resection or stereotactic radiosurgery for local control of solid and cystic cerebellar hemangioblastomas.

The purpose of this study was to identify rates of and risk factors for local tumor progression in patients who had undergone surgery or radiosurgery for the management of cerebellar hemangioblastoma and to describe treatments pursued following tumor progression. The authors conducted a retrospective single-center review of patients who had undergone treatment of a cerebellar hemangioblastoma with either surgery or stereotactic radiosurgery (SRS) between 1996 and 2019. Univariate and multivariate regression analyses were performed to examine factors associated with local tumor control. One hundred nine patients met the study inclusion criteria. Overall, these patients had a total of 577 hemangioblastomas, 229 of which were located in the cerebellum. The surgical and SRS cohorts consisted of 106 and 123 cerebellar hemangioblastomas, respectively. For patients undergoing surgery, tumors were treated with subtotal resection and gross-total resection in 5.7% and 94.3% of cases, respectively. For patients receiving SRS, the mean target volume was 0.71 cm3 and the mean margin dose was 18.0 Gy. Five-year freedom from lesion progression for the surgical and SRS groups was 99% and 82%, respectively. The surgical and SRS cohorts contained 32% versus 97% von Hippel-Lindau tumors, 78% versus 7% cystic hemangioblastomas, and 12.8- versus 0.56-cm3 mean tumor volumes, respectively. On multivariate analysis, factors associated with local tumor progression in the SRS group included older patient age (HR 1.06, 95% CI 1.03-1.09, p < 0.001) and a cystic component (HR 9.0, 95% CI 2.03-32.0, p = 0.001). Repeat SRS as salvage therapy was used more often for smaller tumor recurrences, and no tumor recurrences of < 1.0 cm3 required additional salvage surgery following repeat SRS. Both surgery and SRS achieve high rates of local control of hemangioblastomas. Age and cystic features are associated with local progression after SRS treatment for cerebellar hemangioblastomas. In cases of local tumor recurrence, salvage surgery and repeat SRS are valid forms of treatment to achieve local tumor control, although resection may be preferable for larger recurrences.

Comparison of outcomes following surgical resection, percutaneous ablation or stereotactic body radiation therapy in early-stage, solitary and small (≤3 cm) treatment-naïve hepatocellular carcinoma.

Stereotactic body radiation therapy (SBRT) is associated with high local control rates in hepatocellular carcinoma (HCC). This study reports the outcomes of SBRT compared to surgical resection (SR) and percutaneous ablation (PA) for treatment-naïve, solitary HCCs ≤3 cm. This was a retrospective study of patients with BCLC stage 0/A HCC with a single ≤3 cm lesion, treated with curative intent between 2016 and 2020. SBRT was used for patients considered unsuitable for SR or PA. The co-primary endpoints were progression-free survival (PFS) and overall survival (OS). The secondary endpoints were treatment-related clinical toxicity rates and local control (LC) rates. There were 112 patients included in this study. SBRT was delivered in 36 patients (32.1%), 51 had PA (45.5%) and 25 underwent SR (22.3%). Median follow-up was 23 months (range, 3-60 months) from diagnosis. The 3-year PFS and OS were 67% and 69% following SBRT, 55% and 80% following PA, and 85% and 100% following SR, respectively. Patients in the SR cohort had significantly better 3-year PFS and OS compared to SBRT and PA groups (p = 0.03 and p = 0.04, respectively). There was no significant difference in PFS (p = 0.15) or OS (p = 0.23) between SBRT and PA treated patients. The 3-year LC rate for the entire cohort was 98%. In patients with treatment-naïve, early-stage solitary HCCs ≤3 cm, SBRT was associated with comparable PFS, OS and LC outcomes to PA. SBRT should be considered as a curative intent therapy to avoid treatment stage migration in this favourable prognostic cohort of patients.

Radiation therapy dose escalation achieves high rates of local control with tolerable toxicity profile in pediatric and young adult patients with Ewing sarcoma.

Local control for patients with Ewing sarcoma (EWS) who present with large tumors are suboptimal when treated with standard radiation therapy (RT) doses of 54-55.8Gy. The purpose of this study is to determine local control and toxicity of dose-escalated RT for tumors ≥8cm (greatest diameter at diagnosis) in pediatric and young adult patients with EWS. Eligible patients ≤30years old with newly diagnosed EWS ≥8cm treated with definitive conformal or intensity modulated photon, or proton radiation therapy techniques were included. All patients in the study received dose-escalated RT doses. Outcomes included overall survival (OS), event-free survival (EFS), local failure rates, and toxicity. Thirty-two patients were included, 20 patients presented with metastatic disease and 12 patients with localized disease. The median RT dose was 64.8Gy (range, 59.4-69.4Gy) with variability of doses to protect normal surrounding tissues. All patients received systemic chemotherapy. The 5-year OS and EFS for the cohort was 64.2% and 42%, respectively. The 5-year cumulative incidence of local failure was 6.6%. There were two combined local and distant failures with no isolated local failures. Twenty-nine patients experienced short term toxicity, 90% of those being radiation dermatitis. Twenty-seven patients experienced long-term toxicity, with only one experiencing grade 4 toxicity, a secondary malignancy after therapy. This study demonstrates that definitive RT for pediatric and young adult patients with EWS ≥8cm provides high rates of local control, while maintaining a tolerable toxicity profile.

Abstract A071: Definitive radiation therapy for treatment of non-metastatic pancreatic ductal adenocarcinoma: Practice patterns and outcomes

Abstract Background: Advances in radiation therapy (RT) have allowed for increased biologically effective doses, or ablative RT, to be safely administered to pancreatic tumors. Pancreatic ductal adenocarcinoma (PDA) is diagnosed as local disease without metastasis in roughly 45% of patients (pts) however only 20-25% of pts are candidates for upfront surgical resection, and many are medically unfit to undergo surgery. In such patients, ablative RT can be given with curative intent, termed definitive RT (dRT). Defining practice patterns and outcomes of dRT is needed. Methods: A retrospective chart review was performed on pts with non-metastatic PDA who underwent dRT, defined as &amp;gt; = 100Gy BED over a protracted hypofractionation course, for treatment at our institution. Data collected included: age, gender, primary tumor location, resectability status, surveillance scan frequency and modality, chemotherapy (chemo) used, site of recurrence, cancer antigen (CA) 19-9 levels pre and post dRT, adverse events, and vital status. Neoadjuvant (NA) and adjuvant chemo was defined as chemo received within 6 weeks prior to dRT and 6 weeks after dRT, respectively. Time from diagnosis and dRT until death (OS and dRT-OS, respectively) and time from diagnosis and dRT until progression (PFS and dRT-PFS, respectively) was calculated. Time from diagnosis and dRT until metastasis (MFS and dRT-MFS, respectively) was also calculated. Results: A total of 25 pts who received dRT were identified. Median dose of RT given was 6750 cGY (range 3750-6750) in 15 fractions. Median age at receipt of dRT was 71.5 years (range 50-91), 50% were female. 76% of pts had pancreatic head mass and 24% of pts were considered resectable at time of diagnosis. 2 patients received dRT after isolated local recurrence after surgical resection. 80% of pts received chemo of any kind prior to dRT and 65% of those patients as NA chemo. 35% of patients received 2 chemo regimens prior to dRT; 55% and 65% of patients received mFOLFIRINOX and gemcitabine-based therapy, respectively. 12% of pts received adjuvant chemo. 43% of patients had at least 1 surveillance PET scan. 80% of patients had progression of any kind; of which 85% and 40% experienced distant and local recurrence, respectively. The median OS and dRT-OS was 17.3 months (95% CI 12.2-NA) and 10.1 months (95% CI 6.5-NA), respectively. The median PFS and dRT-PFS was 14.7 months (95% CI 10.3-17.9) and 5.1 months (95% CI 3.6-9.3), respectively. The median MFS and dRT-MFS was 14.7 months (95% CI 10.3-18.0) and 5.6 months (95% CI 3.6-11.3), respectively. Median CA 19-9 pre dRT was 85 (range 4.3-1790) and post-dRT was 42 (range 1.2-1673). 56% of pts had RT-associated toxicity of any kind. Conclusions: Of a single-institutional cohort of 25 patients with non-metastatic PDA who received dRT, more than half of patients received NA chemo; adjuvant chemo was rarely given. dRT provided high rates of local control while MFS was nearly identical to PFS, emphasizing the importance of systemic therapy to reduce distant recurrence in pancreatic cancer treated with dRT. Citation Format: Michael M. Caplan, Brian W. Labadie, Hope Choy, Albert Lee, Weijia Fan, David P. Horowitz. Definitive radiation therapy for treatment of non-metastatic pancreatic ductal adenocarcinoma: Practice patterns and outcomes [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A071.

Predictive clinical and dosimetric parameters for risk of relapse in early-stage non-small cell lung cancer treated by SBRT: A large single institution experience

PurposeTo evaluate the impact of dosimetric parameters on efficacy of stereotactic body radiation therapy (SBRT) in early-stage non-small cell lung cancer (ES-NSCLC), using Hypofractionated Treatment Effects in the Clinic (HyTEC) reporting standards. MethodsFrom April 2010 to December 2020, 497 patients who received SBRT for ES-NSCLC at the University Hospital of Liège were retrospectively enrolled. A total dose of 40 to 60 Gy in 3–5 fractions (72–180 Gy biologically effective dose with an α/β ratio of 10 (BED10)) was prescribed to the 80 % isodose line of the PTV. Potential clinical and dosimetric predictors of recurrence, overall survival (OS) and disease specific survival (DSS) were evaluated using univariate and multivariate analyses. ResultsAfter a median follow-up of 32 months (range 3–143 months), the local control and disease-free survival (DFS) rates at 3 years were 91 % (95 % CI: 90 %–93 %) and 75 % (95 % CI: 73 %–77 %), respectively. The median OS was 41.6 months and the median DSS was not reached. On multivariate analysis, a higher gross tumor volume (GTV) Dmax (BED10) (cut-off 198 Gy) and a larger percent of the GTV receiving ≥110 % of the prescribed dose were predictive of a better local control, only GTV volume was correlated with DSS and no parameter was correlated with OS and regional or distant recurrences. ConclusionLung SBRT for ES-NSCLC in 3 to 5 fractions resulted in high local control rates. A higher percent of GTV receiving ≥110 % of the prescribed dose and a higher GTV Dmax (BED10) seem to allow a better local control.

Treatment outcomes of single-fraction stereotactic radiosurgery for adenoid cystic carcinoma: a case series of 55 patients.

This study aimed to analyze the treatment outcomes of single-fraction stereotactic radiosurgery (SRS) for adenoid cystic carcinoma patients. Retrospective analysis was conducted for 55 patients with 66 lesions. SRS intentions were categorized as definitive, adjuvant, salvage, and palliative. Tumor control was defined as local (within 50% isodose line), marginal (outside 50% isodose line), and distant (metastasis outside head/neck). The median age was 60 years (range 21-85), with 53% males. Tumor origin was head/neck for 88% and trachea/lung for 12%. 61% were recurrent lesions. Median interval from diagnosis to SRS was 14 months. Preceding surgery was performed in 30%. SRS was administered as definitive (30 lesions), adjuvant (13), salvage (19), and palliative (4). SRS was used as a boost to external beam radiation therapy (EBRT) in 39%. Concurrent chemotherapy was administered in 26%. 5-, 10-, and 15-year local control rates were 60%, 33%, and 27%, respectively; local/marginal control rates were 29%, 13%, and 10%. For recurrent lesions treated with SRS without EBRT, 5-year local control rate was 14%, and local/marginal control rate was 5%. For recurrent lesions treated with SRS and EBRT, 5-year local control rate was 100%, and local/marginal control rate was 40%. The rate of distant failure after SRS was 40%. Older age and distant metastasis before SRS were negative factors for overall survival. SRS provided a high rate of local tumor control, but marginal failure was frequent. Integrating SRS with added EBRT exhibits potential for enhancing local and local/marginal tumor control, particularly in recurrent cases.

Stereotactic radiotherapy in the treatment of lung cancer - current prospective

Stereotactic body radiotherapy (SBRT) is the standard treatment for early-stage inoperable non-small cell lung cancer. SBRT achieves a high local control rate (74?100%), preserves the quality of life, and the treatment is of low-toxicity. Different fractionation regimens are used, depending on the localization and size of the tumor, the proximity of the organs at risk, and the general condition of the patient. The radiobiology behind SBRT is largely unknown, precisely defined radiation doses and the number of fractions are still a matter of debate. Numerous studies are ongoing regarding the standardization of SBRT in lung cancer treatment.

Radiation doses of medical radiation workers performing low-dose-rate brachytherapy with 198Au grains and 192Ir pins for patients with oral cancers.

Low-dose-rate brachytherapy (LDR-BT) with 198Au grains and 192Ir pins is an essential treatment option for oral cancer due to its high rate of local control and low invasiveness. However, the radiation exposure of medical radiation workers is concerning. Thus, we aimed to determine the radiation dose delivered to medical radiation workers during LDR-BT using 198Au grains and 192Ir pins for oral cancer. Thirty-two patients with oral cancer underwent 198Au grain interstitial LDR-BT between June 2016 and May 2023, and 23 patients with tongue cancer underwent 192Ir pin interstitial LDR-BT between March 2015 and November 2017 at our hospital. Dosimetry was performed by attaching a dosimeter to the chest pocket of the operator and assistant during 198Au grain or 192Ir pin LDR-BT. Since the operator also loads 198Au grains into the implantation device, the operator's radiation dose includes the dose received during this preparation. Mean radiation doses of the operators with 198Au grain and 192Ir pin LDR-BT were 165.8 and 211.2 μSv, respectively. Statistically significant differences between the radioactive sources of 198Au grain and 192Ir pin LDR-BT were observed (p = 0.0459). The mean radiation doses of the assistants with 198Au grain and 192Ir pin LDR-BT were 92.0 and 162.0 μSv, respectively. Statistically significant differences were observed between the radioactive sources of 198Au grains and 192Ir pin LDR-BT (p = 0.0003). Regarding radioactive source differences, 192Ir pin LDR-BT resulted in higher doses delivered to medical radiation workers than 198Au grain LDR-BT.

Stereotactic ablative radiotherapy for primary renal cell carcinoma

Stereotactic ablative radiotherapy (SAbR) is an emerging non-invasive definitive treatment option for primary renal cell carcinoma (RCC), particularly when surgery is not ideal. Employing ablative doses, SAbR delivered in one to five fractions to the primary tumor has been shown to achieve high local control rates with favorable toxicity profile in multiple retrospective and prospective series, and has dispelled previous notions of RCC radio-resistance. Moreover, emerging evidence suggests possible immunomodulatory effects, leading to clinical investigations of SAbR in combination with systemic and surgical management in patients with metastatic disease. In this review, we summarize key evidence supporting SAbR delivered to the primary tumor including preclinical rationale, dose escalation studies, recent prospective trials, and outcomes from ongoing multi-institutional registries. We also discuss areas of active clinical investigation including the use of primary SAbR in combination with systemic therapies in patients with metastatic disease. The accumulated body of evidence supports SAbR as promising indication being increasingly incorporated into the multi-disciplinary management of primary RCC.

Predictors of local control after robotic stereotactic radiotherapy for brain metastases: 10-years-experience after Cyberknife installation.

To evaluate the factors influencing brain metastases (BM) local control (LC) after stereotactic radiotherapy (SRT). Between 2010 and 2020, a cohort of 145 patients (246 BM) treated consecutively with robotic radiosurgery was analysed. Median age was 61 years (range, 29-90 years). Median radiological follow-up of the lesions was 21.7 months (range, 3-115 months). The mean overall survival and LC were 33.0 and 82.7 months, respectively. On univariate analysis, sex, primary cancer site, histological type, use of systemic steroids, maximum diameter, volume, early MRI response, isodose line, number of fractions, BED10 value, and BED10 value proportional to volume and maximum diameter were significant factors for LC. On multivariate analysis, female sex (hazard ratio [HR]: 2.10 P: 0.035), adenocarcinoma histology (HR: 6.54 P: 0.001), no steroid use (HR: 3.60 P: 0.001), maximum diameter (≤1 cm) (HR: 2.64 P: 0.018), complete response of lesion at first follow-up MRI compared to stable or progressive disease (HR: 4.20, P = 0.024; HR: 19.15, P < 0.001), isodose line (≥90%) (HR: 2.00 P: 0.036), and tumour volume (PTV ≤2 cc) (HR: 5.19 P: 0.001) were independent factors improving LC. SRT is an effective treatment for patients with a limited number of BM with a high LC rate. There are many factors related to the patient, tumour, and radiotherapy plan that have an impact on LC after SRT in brain metastases. These results warrant further investigation in a prospective setting.

RADT-10. BRAINSTEM METASTASES TREATED WITH STEREOTACTIC RADIOSURGERY: MASKED VS. FRAMED IMMOBILIZATION

Abstract BACKGROUND Patients with brainstem metastases (BSM) have minimal surgical options due to high-risk anatomy. To review our efficacy treating BSM using Gamma Knife stereotactic radiosurgery (GK SRS), we compared results based on the utilization of mask-fixation (MF) or frame-fixation (FF). METHODS Data were retrospectively collected for 32 patients. Follow-up data for 49 lesions were analyzed for local control rate (LCR) and objective response rate (ORR). RESULTS Primary cancers included lung, breast, and melanoma; most lesions were pontine. MF was used in 18 patients. Average tumor volume was 0.99 cm3 (0.005 – 13.3 cm3). 39 lesions were treated with single fraction 16 Gy. 10 lesions were treated in 3-5 fractions with mean dose of 22.5 Gy. Mean follow-up was 14.2 months (1.2 - 48.2 months). 1-year LCR was 94.7%. ORR at last follow-up did not differ between MF vs. FF (p = .81). Average reduction of lesion volume at 6 and 12 months did not differ between MF vs. FF (64% vs 45%, p = .77; 70% vs 77%, p = .78). Failure occurred in a pontine colorectal cancer metastasis mask-immobilized for treatment with 14 Gy. CONCLUSIONS SRS for BSM achieved high LCR despite variability in tumor size and histology with no significant difference between MF vs. FF. Although trials have historically excluded patients with BSM, our data support SRS as a safe and efficacious treatment. This is the first study showing that MF provides equivalent, successful outcomes when compared to FF for patients with BSM.