Utility of 68Ga-DOTATATE PET-MRI for Gamma Knife® stereotactic radiosurgery treatment planning for meningioma

OBJECTIVES

To investigate the impact of adding 68Ga-DOTATATE PET/MRI to standard MRI for target volume delineation in Gamma Knife® stereotactic radiosurgery (GKSRS) for meningioma.

METHODS

Seventeen patients with 18 lesions undergoing GKSRS for WHO grade 1 meningioma were enrolled in a prospective study. All patients underwent pre-treatment 68Ga-DOTATATE PET/MRI examination in addition to standard procedures. Five clinicians independently contoured the gross tumour volume (GTV) based on standard MRI (GTVMRI) and PET/MRI (GTVPET/MRI) on separate occasions. Interobserver agreement was evaluated using Cohen's Kappa statistic (CKS), Dice similarity coefficient (DC), and Hausdorff distance (HD). Statistical analysis was performed with paired t-test and Wilcoxon signed rank test.

RESULTS

The addition of PET/MRI significantly increased GTV contour volume (mean GTVPET/MRI 3.59 cm3 versus mean GTVMRI 3.18 cm3, P = .008). Using the treating clinician's pre-treatment GTVMRI as the reference, median CKS (87.2 vs 77.5, P = .006) and DC (87.2 vs 77.4, P = .006) were significantly lower, and median HD (25.2 vs 31.0, P = .001) was significantly higher with the addition of PET/MRI. No significant difference was observed in interobserver contouring reproducibility between GTVMRI and GTVPET/MRI.

CONCLUSION

The addition of 68Ga-DOTATATE PET/MRI for target volume delineation in GKSRS for meningioma is associated with an increase in GTV volume and greater interobserver variation. PET/MRI did not affect interobserver contouring reproducibility.

ADVANCES IN KNOWLEDGE

This study provides novel insights into the impact of 68Ga-DOTATATE PET/MRI on GTV delineation and interobserver agreement in meningioma GKSRS, highlighting its potential for improving GKSRS treatment accuracy.

The impact of local control on widespread progression and survival in oligometastasis-directed SBRT: Results from a large international database

PURPOSE

We investigated the impact of local control (LC) on widespread progression (WSP) and overall survival (OS) in patients treated to all extracranial oligometastases (OMs) at presentation to SBRT in this retrospective review across 6 international centers.

MATERIALS/METHODS

Relationships between LC status of SBRT-directed OMs and OS and WSP (>5 new active/untreated lesions) were explored using Cox and Fine-Gray regression models, adjusting for radioresistant histology and pre-SBRT systemic therapy receipt. The association between LC and dosimetric predictors was analyzed with competing risk regression using death as a competing risk and across a wide range of simulated α/βratios.

RESULTS

In total, 1700 OMs in 1033 patients were analyzed, with 25.2% NSCLC, 22.7% colorectal, 12.8% prostate, and 8.1% breast histology. Patients who failed locally in any SBRT-directed OM within 6 mo were at 3.6-fold higher risk of death and 2.7-fold higher risk of WSP compared to those who remained locally-controlled (p < 0.001). Similar associations existed for each duration of LC investigated through 3 yrs post-SBRT. There was no significant difference in risk of WSP or death between patients who failed in a subset of SBRT-treated lesions vs. patients who failed in all lesions. Minimum dose (Dmin) to the GTV/ITV was most predictive of LC when compared to prescription dose, PTV Dmin, and PTV Dmax. Sensitivity analysis for achieving 1-yr LC > 95% found thresholds of 41.2 Gy and 55.2 Gy in 5 fractions for smaller (< 27.7 cc) and larger radioresistant lesions, respectively.

CONCLUSION

This large multinational cohort suggests that the duration of LC following OM-directed SBRT strongly correlates with WSP and OS.

Stereotactic radiosurgery for melanoma brain metastases: Concurrent immune checkpoint inhibitor therapy associated with superior clinicoradiological response outcomes

INTRODUCTION/PURPOSE

This study assessed long-term clinical and radiological outcomes following treatment with combination stereotactic radiosurgery (SRS) and immunotherapy (IT) for melanoma brain metastases (BM).

METHODS

A retrospective review was performed in a contemporary cohort of patients with melanoma BM at a single tertiary institution receiving Gamma Knife^® SRS for melanoma BM. Multivariate Cox proportional-hazards modelling was performed with a P <0.05 for significance.

RESULTS

101 patients (435 melanoma BM) were treated with SRS between January-2015 and June-2019. 68.3% of patients received IT within 4 weeks of SRS (concurrent) and 31.7% received SRS alone or non-concurrently with IT. Overall, BM local control rate was 87.1% after SRS. Median progression free survival was 8.7 months. Median follow-up was 29.2 months. On multivariate analysis (MVA), patients receiving concurrent SRS-IT maintained a higher chance of achieving a complete (CR) or partial response (PR) [HR 2.6 (95% CI: 1.2-5.5, P = 0.012)] and a reduced likelihood of progression of disease (PD) [HR 0.52 (95% CI: 0.16-0.60), P = 0.048]. Any increase in BM volume on the initial MRI 3 months after SRS predicted a lower likelihood of achieving long-term CR or PR on MVA accounting for concurrent IT, BRAF status and dexamethasone use [HR = 0.048 (95% CI: 0.007-0.345, P = 0.0026)]. Stratified volumetric change demonstrated a sequential relationship with outcomes on Kaplan-Meier analysis.

CONCLUSION

Concurrent SRS-IT has favourable clinical and radiological outcomes with respect to CR, PR and a reduced likelihood of PD. Changes in BM volume on the initial MRI 3 months after SRS were predictive of long-term outcomes for treatment response.

An analysis of a large multi-institutional database reveals important associations between treatment parameters and clinical outcomes for stereotactic body radiotherapy (SBRT) of oligometastatic colorectal cancer

PURPOSE

In recent years, stereotactic body radiotherapy (SBRT) has emerged as an effective treatment for oligometastatic cancers. Here, we report radiation treatment parameters and clinical outcomes for patients with oligometastatic colorectal cancer (CRC) treated with SBRT using a large multi-institutional database.

METHODS

Patients with extra-cranial oligometastatic CRC (≤ 5 lesions) treated with SBRT at six large academic cancer centers were included. The primary outcome was local recurrence while secondary outcomes included overall survival (OS) progression free survival, oligo-progression, and widespread progression. Survival outcomes were estimated using the Kaplan-Meier method. Univariable and multivariable analyses were performed to determine the relationship between patient and treatment characteristics and clinical outcomes.

RESULTS

We identified 235 patients with a total of 381 oligometastatic CRC lesions. The 1- and 5-year local recurrence rate was 13.6% and 44.3% respectively. The median OS was 49 months with a 2-and 5-year OS of 76.1% and 35.9%, respectively. On multivariable analysis, a BED₁₀ of ≥120 Gy, and lung versus liver metastases were associated with a reduction in local recurrence. Larger total PTV size (≥17.5cc) was associated with worse overall survival, progression free survival, and widespread progression.

CONCLUSION

This large multi-institutional analysis found that the use of SBRT for oligometastatic colorectal cancer resulted in favorable overall survival. However, local recurrence is higher than expected for ablative radiation treatment. An increase in BED₁₀ should be considered if feasible and safe.

Volumetric burden of metastatic lesions drives outcomes in patients with extracranial oligometastatic disease

Background

We hypothesized that the total volume of metastases at initial oligometastatic (OM) presentation to stereotactic body radiation therapy (SBRT) is an important prognostic factor that can refine the definition of OM disease.

Methods

Patients with extracranial oligometastatic cancer (≤5 lesions) treated with SBRT were included in an international multi‐institutional database. Multivariable Cox and competing risks regression models were used to determine the relationship between distant progression‐free survival (DPFS), widespread progression (WSP), and overall survival (OS) with the total planning target volume (PTV) at initial OM presentation to SBRT. All models were adjusted for histology, pre‐SBRT systemic therapy, osseous‐only lesions, and number of metastases.

Results

In total, 961 patients were included. The median follow‐up was 24.4 months (IQR: 13.8–37.5). Total PTV had a significant effect on DPFS in the first 18 months after SBRT and was most profound in the first 6 months, when each twofold increase in total PTV conferred a 40.6% increased risk of distant progression (p < 0.001). Each twofold increase in total PTV increased the risk of WSP by 45.4% in the first 6 months (p < 0.001). Total PTV had a significant effect on OS in the first 2 years after SBRT, with each twofold PTV change increasing the risk of death by 60.7% during the first 6 months (p < 0.001) and by 34% thereafter (p < 0.001). Exploratory gross tumor volume (GTV) analysis confirmed the PTV‐based observations.

Conclusion

The total volumetric burden of metastases at initial OM presentation to SBRT is strongly and independently prognostic for the risk of distant and widespread progression and survival. We propose that this metric should drive the definition of OM disease and guide treatment decision‐making.

Outcomes Following Hypofractionated Stereotactic Radiotherapy to the Cavity After Surgery for Melanoma Brain Metastases

AIMS

Hypofractionated stereotactic radiotherapy (HSRT) to the cavity after surgical resection of brain metastases improves local control. Most reported cohorts include few patients with melanoma, a population known to have high rates of recurrence and neurological death. We aimed to assess outcomes in patients with melanoma brain metastases who received HSRT after surgery at two Australian institutions.

MATERIALS AND METHODS

A retrospective analysis was carried out including patients treated between January 2012 and May 2020. HSRT was recommended for patients with melanoma brain metastases at high risk of local recurrence after surgery. Treatment was delivered using appropriately commissioned linear accelerators. Routine follow-up included surveillance magnetic resonance imaging brain every 3 months for at least 2 years. Primary outcomes were overall survival, local control, incidence of radiological radionecrosis and symptomatic radionecrosis.

RESULTS

There were 63 cavities identified in 57 patients. The most common HSRT dose prescriptions were 24 Gy in three fractions and 27.5 Gy in five fractions. The median follow-up was 32 months in survivors. Local control was 90% at 1 year, 83% at 2 years and 76% at 3 years. Subtotal brain metastases resection (hazard ratio 12.5; 95% confidence interval 1.4-111; P = 0.0238) was associated with more local recurrence. Overall survival was 64% at 1 year, 45% at 2 years and 40% at 3 years. There were 10 radiological radionecrosis events (16% of cavities) during the study period, with 5% at 1 year and 8% at 2 years after HSRT. The median time to onset of radiological radionecrosis was 21 months (range 6-56). Of these events, three became symptomatic (5%) during the study period at a median time to onset of 26 months (range 21-32).

CONCLUSION

Cavity HSRT is associated with high rates of local control in patients with melanoma brain metastases. Subtotal resection strongly predicts for local recurrence after HSRT. Symptomatic radionecrosis occurred in 5% of cavities but increased to 8% of longer-term survivors.

An international pooled analysis of SBRT outcomes to oligometastatic spine and non-spine bone metastases

PURPOSE

There is a paucity of data on SBRT to non-spine bone (NSB) lesions compared to spine metastases. We report local recurrence (LR), widespread progression (WSP), and overall survival (OS) for oligometastatic patients treated to bone lesions with SBRT and investigate the hypothesis that outcomes are different between patients with spine and non-spine bone oligometastatic disease.

METHODS

Patients with oligometastatic disease (≤5 cumulative extracranial metastases) treated with bone SBRT at 6 international institutions from 2007 to 2016 were reviewed. Fine and Gray competing risks and Cox regressions were used to analyze univariable and multivariable relationships between disease/treatment factors and outcomes.

RESULTS

In total, 288 spine and 233 NSB lesions are reported in 356 patients. Cumulative incidence of LR across all bone lesions was 6.3%, 12.6% and 19.3% at 6 mo, 1 yr and 2 yrs. While univariable analysis suggested inferior LC and OS in spine patients, this did not hold true in multivariable analysis. The final regression model for LR in NSB lesions included PTV ≥ median of 31.8 cc (HR 5.02, p = 0.014) and primary histology, with RCC and NSCLC conferring a 10.8- and 6.5-fold increased risk of LR compared to prostate histology, respectively. The spine LR model included radioresistant histology (HR 2.11, p = 0.0051), PTV Dmin (BED10) ≥ median of 19.1 Gy (HR 0.46, p = 0.0085), and epidural disease (HR 1.99, p = 0.016).

CONCLUSION

This large multi-institutional series reports comparably excellent response to SBRT for a balanced distribution of oligometastatic NSB and spine lesions. Dose escalation for large and/or radioresistant NSB lesions should be explored, given the typical lack of an immediately adjacent dose-limiting critical structure.

A randomized phase II trial of veliparib, radiotherapy and temozolomide in patients with unmethylated MGMT glioblastoma: the VERTU study

Background

Temozolomide offers minimal benefit in patients with glioblastoma with unmethylated O⁶-methylguanine-DNA methyltransferase (MGMT) promoter status, hence, the need for novel therapies. This study evaluated whether veliparib, a brain-penetrant poly(ADP-ribose) polymerase (PARP) inhibitor, acts synergistically with radiation and temozolomide.

Methods

VERTU was a multicenter 2:1 randomized phase II trial in patients with newly diagnosed glioblastoma and MGMT-unmethylated promotor status. The experimental arm consisted of veliparib and radiotherapy, followed by adjuvant veliparib and temozolomide. The standard arm consisted of concurrent temozolomide and radiotherapy, followed by adjuvant temozolomide. The primary objective was to extend the progression-free survival rate at six months (PFS-6m) in the experimental arm.

Results

A total of 125 participants were enrolled, with 84 in the experimental arm and 41 in the standard arm. The median age was 61 years, 70% were male, 59% had Eastern Cooperative Oncology Group (ECOG) performance status of 0, and 87% underwent macroscopic resection. PFS-6m was 46% (95% confidence interval [CI]: 36%-57%) in the experimental arm and 31% (95% CI: 18%-46%) in the standard arm. Median overall survival was 12.7 months (95% CI: 11.4-14.5 months) in the experimental arm and 12.8 months (95% CI: 9.5-15.8 months) in the standard arm. The most common grade 3-4 adverse events were thrombocytopenia and neutropenia, with no new safety signals.

Conclusion

The veliparib-containing regimen was feasible and well tolerated. However, there was insufficient evidence of clinical benefit in this population. Further information from correlative translational work and other trials of PARP inhibitors in glioblastoma are still awaited.

Multi-institutional Analysis of Prognostic Factors and Outcomes After Hypofractionated Stereotactic Radiotherapy to the Resection Cavity in Patients With Brain Metastases

IMPORTANCE

For brain metastases, the combination of neurosurgical resection and postoperative hypofractionated stereotactic radiotherapy (HSRT) is an emerging therapeutic approach preferred to the prior practice of postoperative whole-brain radiotherapy. However, mature large-scale outcome data are lacking.

OBJECTIVE

To evaluate outcomes and prognostic factors after HSRT to the resection cavity in patients with brain metastases.

DESIGN, SETTING, AND PARTICIPANTS

An international, multi-institutional cohort study was performed in 558 patients with resected brain metastases and postoperative HSRT treated between December 1, 2003, and October 31, 2019, in 1 of 6 participating centers. Exclusion criteria were prior cranial radiotherapy (including whole-brain radiotherapy) and early termination of treatment.

EXPOSURES

A median total dose of 30 Gy (range, 18-35 Gy) and a dose per fraction of 6 Gy (range, 5-10.7 Gy) were applied.

MAIN OUTCOMES AND MEASURES

The primary end points were overall survival, local control (LC), and the analysis of prognostic factors associated with overall survival and LC. Secondary end points included distant intracranial failure, distant progression, and the incidence of neurologic toxicity.

RESULTS

A total of 558 patients (mean [SD] age, 61 [0.50] years; 301 [53.9%] female) with 581 resected cavities were analyzed. The median follow-up was 12.3 months (interquartile range, 5.0-25.3 months). Overall survival was 65% at 1 year, 46% at 2 years, and 33% at 3 years, whereas LC was 84% at 1 year, 75% at 2 years, and 71% at 3 years. Radiation necrosis was present in 48 patients (8.6%) and leptomeningeal disease in 73 patients (13.1%). Neurologic toxic events according to the Common Terminology Criteria for Adverse Events grade 3 or higher occurred in 16 patients (2.8%) less than 6 months and 24 patients (4.1%) greater than 6 months after treatment. Multivariate analysis identified a Karnofsky Performance Status score of 80% or greater (hazard ratio [HR], 0.61; 95% CI, 0.46-0.82; P < .001), 22 to 33 days between resection and radiotherapy (HR, 1.50; 95% CI, 1.07-2.10; P = .02), and a controlled primary tumor (HR, 0.69; 95% CI, 0.52-0.90; P = .007) as prognostic factors associated with overall survival. For LC, a single brain metastasis (HR, 0.57; 95% CI, 0.35-0.93; P = .03) and a controlled primary tumor (HR, 0.59; 95% CI, 0.39-0.92; P = .02) were significant in the multivariate analysis.

CONCLUSIONS AND RELEVANCE

To date, this cohort study includes one of the largest series of patients with brain metastases and postoperative HSRT and appears to confirm an excellent risk-benefit profile of local HSRT to the resection cavity. Additional studies will help determine radiation dose-volume parameters and provide a better understanding of synergistic effects with systemic and immunotherapies.

The declining role of post-treatment neck dissection in human papillomavirus-associated oropharyngeal cancer

BACKGROUND AND PURPOSE

Human papillomavirus-associated oropharyngeal cancer (HPV+ OPC) with regional lymph node metastases has a good prognosis following (chemo)radiation therapy (C/RT) but lymph nodes may remain detectable for several months. Delayed [¹⁸F]-Fluorodeoxyglucose positron emission tomography/computed tomography (PET) can identify patients who may avoid post-treatment neck dissection (PTND). We investigated the rate of PTND in HPV+ OPC treated with C/RT and delayed PET-directed management of the neck.

MATERIALS AND METHODS

This is a retrospective cohort study from a prospectively updated institutional database. Eligible patients were treated between January 2005 and July 2017 with a minimum of 18 months follow up, had node-positive, non-distant metastatic HPV+ OPC and were treated with RT (70 Gy/35#/5 per week) with concurrent Cisplatin or Cetuximab, or accelerated RT alone (68 Gy/34#/6 per week). The primary endpoint was rate of PTND. Secondary endpoints were locoregional failure free survival (LRFFS), regional failure free survival (RFFS), distant metastatic failure free survival (DMFFS), overall survival (OS) and oropharyngeal cancer-specific survival (CSS).

RESULTS

418 patients were eligible. Nineteen patients (4.5%) received a PTND. None of the tested variables were associated with an increased risk of PTND. Five-year probabilities for LRFFS, RFFS, DMFS, OS and CSS were, 91.2% (95% CI 88.3-94.2), 93.4% (95% CI 90.8-96.0), 91.2% (95% CI 88.3-94.2), 86.4% (95% CI 83.0-90.1) and 90.2% (95% CI 87.1-93.4), respectively.

CONCLUSION

In a large cohort with good median follow up and protocolized C/RT, delayed PET-directed management of the neck affords a lower rate of PTND than reported in historical series without compromising disease control and survival.

Health-related quality of life (HRQL) in VERTU: A randomized phase II trial of veliparib (V), radiotherapy (RT), and temozolomide (TMZ) for newly diagnosed MGMT unmethylated (uMGMT) glioblastoma (GBM)

2042

Background: The VERTU trial (ANZCTR #ACTRN12615000407594) compared Arm A (standard of care) = RT (60Gy/30 fractions) + TMZ (75mg/m2 daily) followed by TMZ (150–200mg/m2 D1–5) every 28 days for 6 cycles vs Arm B (experimental arm) = RT (60Gy/30 fractions) + V (200mg PO BID) followed by TMZ (150–200mg/m2 D1–5) + V (40mg PO BID, D1–7) every 28 days for 6 cycles in pts with newly diagnosed centrally determined uMGMT GBM. To ensure that veliparib was not associated with clinical detriment, serial HRQL assessments were performed for comparison as a secondary objective. Methods: Pts completed the EORTC quality of life core questionnaire (QLQ-C30) and brain cancer module (BN20) every 4 weeks (w) (baseline: w0; concurrent: w4,8; adjuvant: w10,14,18,22,26,30). Based on relevance to GBM patients, 5 HRQL scales (global health [GH], physical functioning [PF], social functioning [SF], motor dysfunction [MD] and communication deficit [CD]) were pre-selected for primary analysis. Maximum change from baseline score (clinically relevant deterioration/improvement defined as ≥10-point change) during the progression-free period, and deterioration-free survival (time to deterioration/progression/death) were evaluated. Results: Patient characteristics were well-matched (Arm A: N = 41, median age = 62, male = 68%, ECOG 0 = 66%, macroscopic resection = 88%; Arm B: N = 84, median age = 60, male = 70%, ECOG 0 = 65%, macroscopic resection = 86%). Almost all completed at least one HRQL assessment (98%). HRQL assessments during the progression-free period were completed in 87% (Arm A) and 90% (Arm B) of cases. For Arm A vs B, the proportion of patients who experienced a deterioration in GH (59% vs 64%, p = 0.69), PF (53% vs 53%, p > 0.99), SF (46% vs 53%, p = 0.56), MD (63% vs 58%, p = 0.70) and CD (45% vs 46%, p > 0.99) were similar. Deterioration-free survival was not statistically different for any HRQL item. Conclusions: The addition of veliparib to standard of care for newly diagnosed uMGMT GBM does not appear to compromise HRQL. This would support the primary efficacy analysis of the VERTU trial. Clinical trial information: ACTRN12615000407594.

A phase II, open label, randomized controlled trial of nivolumab plus ipilimumab with stereotactic radiotherapy versus ipilimumab plus nivolumab alone in patients with melanoma brain metastases (ABC-X Trial)

TPS9600

Background: Nivolumab combined with ipilimumab is active in melanoma brain metastases, with intracranial response rates > 55% and durable survival in treatment naïve patients (pts) (Long GV et al Lancet Onc 2018; Tawbi H et al NEJM 2018). We seek to determine if the addition of stereotactic radiotherapy (SRS) results in improved intracranial outcomes. Methods: This is a multisite, open-label, phase 2 trial in systemic treatment-naïve pts with melanoma brain metastases. Pts must have ≥1 asymptomatic brain metastases that are ≥5mm and ≤40mm as per modified RECIST 1.1, on gadolinium-enhanced MRI, and no history of previous treatment with SRS. Eligible pts are randomly assigned to either receive nivolumab plus ipilimumab with SRS or nivolumab plus ipilimumab alone. Nivolumab (1mg/kg) and ipilimumab (3mg/kg) are given every 3 weeks for 4 doses. Following induction, 480mg nivolumab is given every 4 weeks until progression, unacceptable toxicity, or a maximum of 2 years. SRS is administered as single fraction of 16-22Gy, or hypofractionated for larger lesions (24-27Gy in 3 fractions), within 7 days of immunotherapy commencement. Pts will be evaluated for intracranial and extracranial tumour response, and overall response, every 6 weeks to week 24 and 12 weekly thereafter until overall disease progression or death. The primary endpoint is neurologic specific survival (NSS) at 12 months. Secondary endpoints include intracranial response rate, intracranial PFS, overall PFS, overall progression free survival, overall survival, neurocognitive function and incidence of radiation necrosis. 109 patients in each cohort (218 total) will achieve > 80% power at the significance level (alpha) of 0.10 to detect a minimum absolute increase of 9% in the NSS rate at 12 months. Clinical trial information: NCT03340129.

A randomized phase II trial of veliparib (V), radiotherapy (RT) and temozolomide (TMZ) in patients (pts) with unmethylated MGMT (uMGMT) glioblastoma (GBM)

2011

Background: TMZ offers minimal benefit in uMGMT GBM pts. V is synergistic with both RT and TMZ in preclinical models, safe when combined with either RT or TMZ clinically, but the triplet (V+RT+TMZ) is poorly tolerated. This study examined a novel approach to patients with uMGMT GBM. Methods: VERTU is a randomized Phase 2 trial comparing Arm A (Standard of care) = RT (60Gy/30 fractions) + TMZ (75mg/m2 daily) followed by TMZ (150–200mg/m2D 1–5) every 28 days for 6 cycles vs Arm B (experimental arm) = RT (60Gy/30 fractions) + V (200mg PO BID) followed by TMZ (150–200mg/m2D 1–5) + V (40mg bid, D 1–7) every 28 days for 6 cycles in pts with newly diagnosed centrally determined uMGMT GBM. The study aims to randomize 120 pts (2:1 to the experimental arm). The primary endpoint was 6 months progression free survival (6mPFS) with multiple secondary and tertiary endpoints. Evaluation of feasibility and safety was planned after completion of RT in the first 60 pts (Stage 1). (ANZCTR #ACTRN12615000407594). Tumor tissue and serial bloods were collected for translational research. Results: 125 pts were randomized (41 Arm A, 84 Arm B). Mean (range) age 58 (22–78) years, 70% male, 61% ECOG 0, 86% macroscopic resection, 14% biopsy. At the time of analysis (cut-off date: 04/Feb/2019), median follow up was 16.5 months, 76 pts had died. 6mPFS (95% CI, Kaplan-Meier estimate) was 37% (22–52) in Arm A and 53% (41–63) in Arm B, and median PFS was 4.4m (95% CI 4.0–6.0) for Arm A and 6.2m (95% CI 4.9–7.1) for Arm B (HR = 0.81, 95%CI 0.54–1.21). 50% of pts in Arm A and 53% in Arm B experienced ≥ G3 adverse events (AEs). The most common G 3/4 AEs were decreased platelets, seizures, hyperglycemia and diarrhea (each 5%) in Arm A and decreased platelets (13%) and seizures (11%) in Arm B. Conclusions: In this multicenter, randomized study, the experimental therapy was feasible and well tolerated. The observed 6mPFS appeared longer in Arm B, but at the time of submitting the abstract, this result did not meet the prespecified primary endpoint. More mature results will be presented at the annual meeting. QoL in VERTU is reported separately. Central MR review, biomarker analyses, including DNA repair and methylation signature analyses are ongoing. Clinical trial information: ACTRN12615000407594.

Proceedings of the 2018 next-generation Gamma Knife research meeting

In order to determine what areas of research are a clinical priority, a small group of young Gamma Knife investigators was invited to attend a workshop discussion at the 19th International Leksell Gamma Knife Society Meeting. Two areas of interest and the need for future radiosurgical research involving multiple institutions were identified by the young investigators working group: 1) the development of additional imaging sequences to guide the understanding, treatment, and outcome tracking of diseases such as tremor, radiation necrosis, and AVM; and 2) trials to clarify the role of hypofractionation versus single-fraction radiosurgery in the treatment of large lesions such as brain metastases, postoperative cavities, and meningiomas.

Radiological Kinetics of Brain Metastases and Clinical Implications for Patients Treated With Stereotactic Radiosurgery

AIMS

Select patients with brain metastases receive stereotactic radiosurgery (SRS) with the objective of improving survival and intracranial disease control. Brain metastases number and volume are prognostic factors used to inform patient selection. The aim of this study was to assess the rate of change of brain metastases size and number (growth kinetics) between the diagnostic and day of SRS magnetic resonance imaging (MRI) scans.

MATERIALS AND METHODS

All patients treated with Gamma Knife SRS between October 2015 and April 2017 were included in this single-centre retrospective analysis. Brain metastases number and diameter were recorded at diagnosis and treatment. For patients with multiple brain metastases, the largest lesion was the index lesion. Distant intracranial control and overall survival were reported from the date of SRS.

RESULTS

In total, 146 patients received 156 episodes of SRS. The median interval between diagnostic and SRS MRI was 20 days (range 1-68). Interval growth in the index lesion of at least 3 mm or the development of a new brain metastasis was noted in 60.2% of patients. This was associated with age less than 60 years (P = 0.001), Eastern Cooperative Oncology Group (ECOG) performance status 2 or above (P = 0.04), non-small cell lung carcinoma (NSCLC) (P = 0.03) or melanoma histologies (P = 0.05) and uncontrolled extracranial disease (P = 0.05). These patients were also more likely to develop distant intracranial recurrence (P = 0.046). Clinically significant growth was not associated with scan interval or differences in overall survival. The Kaplan-Meier estimate of probability of survival at 12 months was 59.3% (95% confidence interval 46.7-75.2%) for all patients.

CONCLUSION

Intracranial progression between diagnosis and day of SRS is common. Risk factors are uncontrolled extracranial disease, poorer performance status, NSCLC or melanoma histologies and age less than 60 years. These patients would benefit from an MRI closer to treatment to inform patient selection and target delineation for SRS planning.

Re-irradiation for recurrent high-grade gliomas: a systematic review and analysis of treatment technique with respect to survival and risk of radionecrosis

Background

Re-irradiation may be considered for select patients with recurrent high-grade glioma. Treatment techniques include conformal radiotherapy employing conventional fractionation, hypofractionated stereotactic radiotherapy (FSRT), and single-fraction stereotactic radiosurgery (SRS).

Methods

A pooled, population-weighted, multiple linear regression analysis of publications from 1992 to 2016 was performed to evaluate the relationships between re-irradiation technique and median overall survival (OS) and radionecrosis outcomes.

Results

Seventy published articles were analyzed, yielding a total of 3302 patients. Across all studies, initial treatment was external beam radiotherapy to a median dose of 60 Gy in 30 fractions, with or without concurrent chemotherapy. On multivariate analysis, there was a significant correlation between OS and radiotherapy technique after adjusting for age, re-irradiation biologically equivalent dose (EQD2), interval between initial and repeat radiotherapy, and treatment volume (P < .0001). Adjusted mean OS was 12.2 months (95% CI, 11.8-12.5) after SRS, 10.1 months (95% CI, 9.7-10.5) after FSRT, and 8.9 months (95% CI, 8.4-9.4) after conventional fractionation. There was also a significant association between radionecrosis and treatment technique after adjusting for age, re-irradiation EQD2, interval, and volume (P < .0001). Radionecrosis rate was 7.1% (95% CI, 6.6-7.7) after FSRT, 6.1% (95% CI, 5.6-6.6) after SRS, and 1.1% (95% CI, 0.5-1.7) after conventional fractionation.

Conclusions

The published literature suggests that OS is highest after re-irradiation using SRS, followed by FSRT and conventionally fractionated radiotherapy. Whether this represents superiority of the treatment technique or an uncontrolled selection bias is uncertain. The risk of radionecrosis was low for all modalities overall. Re-irradiation is a feasible option in appropriately selected patients.

In response to Fogarty et al. and why adjuvant whole brain radiotherapy is not recommended routinely

The routine use of adjuvant whole brain radiotherapy (AWBRT) after surgery or stereotactic radiosurgery is now discouraged by a number of international expert panels. Three decades of randomised studies have shown that, although AWBRT improves radiological measures of intracranial disease control, the clinical benefit is unclear and it is also associated with inferior quality of life and neurocognitive function. The number of patients with melanoma in these trials was low, but data suggesting that treatment-related side effects should vary according to histology of the primary malignancy are lacking. For metastatic melanoma, the role of AWBRT to control microscopic disease in the brain is also a less relevant concern because systemic therapies with intracranial activity are now available. Whether AWBRT is useful in select patients deemed at high risk of neurologic death remains undefined.

The influence of cisplatin de-escalation on survival outcomes in oropharyngeal head and neck squamous cell carcinoma (OPC)

e17551

Background: Chemoradiotherapy (CRT) with 3 cycles (#) of high-dose cisplatin (HDC) (100mg/m2 weeks 1,4 & 7) and 70Gy over 7 weeks is associated with improved overall survival (OS) compared with radiotherapy (RT) alone in locally advanced OPC. Human Papilloma Virus (HPV) related tumours have superior outcomes and de-escalating treatment is a contemporary issue. Our study objectives were to determine if 2# HDC were non-inferior to 3#, how this was influenced by prognostic factors including stage, smoking history and p16 status, and to explore toxicity attributed to HDC. Methods: A single centre, retrospective analysis was undertaken for OPC patients who received CRT with HDC between Oct 2009 -Dec 2012. Those with distant metastatic disease or receiving induction chemotherapy were excluded. Data extracted included HPV and smoking status, tumour stage by 7thEd AJCC TNM and ICON-S classification, # HDC completed, toxicity and OS. Log-rank test was used for OS analysis. Results: 63, 96 and 4 patients received 3, 2 and 1 # HDC respectively. Median RT dose was 70Gy (range 66-70). 110 (67.5%) were p16 +, 28 (17.2%) were p16 negative and 25 (15.3%) unknown. 52 had omission of #3 HDC predominantly due to neutropenia (33%), nephrotoxicity (23%) and ototoxicity (12%). 19 had delays in #2 HDC resulting in omission of #3 due to completion of RT. There was no difference in OS between 3 #(mean OS (yrs)+/- SEM: 6.05+/- 0.22) or 2# HDC (5.70+/- 0.21) in all comers (p = 0.255). For RTOG0129 low risk p16+ patients, there was no significant difference (p = 0.896) between 3# (6.33+/- 0.24; n = 24) and 2# (6.18+/- 0.25; n = 44) HDC. Similar results were evident for ICON-S stage I for 3# (6.36+/-0.19; n = 25) vs 2# (6.30+/- 0.19; n = 42) HDC (p = 0.932). For RTOG 0129 intermediate risk p16 + OPC there was a significant difference (p = 0.017) in OS favouring 3# (6.29+/-0.22; n = 20) versus 2# (4.81+/-0.67; n = 10) HDC. For p16 negative patients there was no difference (p = 0.265) in OS between 3# (4.06+/-0.94; n = 9) and 2# (5.17+/-0.48; n = 22) HDC. Conclusions: This data suggests that cisplatin de-escalation does not confer inferior OS in low risk HPV related OPC. Significant toxicities with HDC influenced the ability to complete prescribed treatment.

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

AIM

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

MATERIALS & METHODS

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

RESULTS & CONCLUSION

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

A multi-national report on stereotactic body radiotherapy for oligometastases: Patient selection and follow-up

Aims Stereotactic body radiotherapy (SBRT) for oligometastases is increasingly used with few evidenced-based guidelines. We conducted a survey to determine patient selection and follow-up practice patterns. Materials and methods Seven institutions from US, Canada, Europe, and Australia that recommend SBRT for oligometastases participated in a 72-item survey. Levels of agreement were categorized as strong (6-7 common responses), moderate (4-5), low (2-3), or no agreement. Results There was strong agreement for recommending SBRT for eradication of all detectable oligometastases with most members limiting the number of metastases to five (range 2-5) and three within a single organ (range 2-5). There was moderate agreement for recommending SBRT as consolidative therapy after systemic therapy. There was strong agreement for requiring adequate performance status and no concurrent chemotherapy. Additional areas of strong agreement included staging evaluations, primary diagnosis, target sites, and follow-up recommendations. Several differences emerged, including the use of SBRT for sarcoma oligometastases, treatment response evaluation, and which imaging should be performed during follow-up. Conclusion Significant commonalities and variations exist for patient selection and follow-up recommendations for SBRT for oligometastases. Information from this survey may serve to help clarify the current landscape.

Melanoma brain metastases: the impact of nodal disease

Brain metastases (BMs) are a major source of mortality and morbidity in patients with melanoma. This study assesses prognostic nodal factors in patients with nodal metastatic melanoma with respect to the development of BMs. The aim was to identify a high risk subset that may benefit from brain directed management. Prospective surgical and clinical trial databases identified patients who had had nodal dissections and were seen through the Princess Alexandra Hospital Melanoma clinic between August 1995 and June 2010. Patient data was collected and event data was updated from medical imaging and clinical records. The primary endpoint was the rate of development of BMs. 474 patients were identified as having nodal dissections. Two hundred and eighty-seven patients (61%) were male with a median age of 52 (39-66). The most common nodal dissection site was axilla 190 (40%), followed by groin 154 (32.5%) and neck 130 (27.5%). Adjuvant radiotherapy to the nodal basin was delivered to 134 patients (28%). BMs occurred in 61 patients (12.9%) with a median time of 13.87 months from dissection. No lymph node characteristics were significantly associated with the development of BMs including: nodal region (p=0.72), nodal size (p=0.08), number of involved nodes (p=0.36), presence of extra-capsular spread (p=0.47) and AJCC N stage. There was no significant association between primary ulceration (p=0.37) or location and development of BMs. It appears that for patients with resected stage III melanoma there is no histopathological lymph node feature associated with the development of BMs. This highlights the importance of identifying molecular markers in nodal melanoma which may predict for BMs to further direct site-specific therapy.

Hippocampal-sparing radiotherapy: the new standard of care for World Health Organization grade II and III gliomas?

The neurocognitive effects of cranial radiotherapy in patients with gliomas are well-recognised and may be related to the dose delivered to the hippocampi. Intensity modulated radiotherapy (IMRT) is a radiotherapy technique that can be used to selectively spare the hippocampi without compromising the dose delivered to the tumour. This study aimed to evaluate if hippocampal-sparing IMRT is achievable in patients with World Health Organization (WHO) grade II and III gliomas. A retrospective review of consecutive patients with WHO grade II and III gliomas treated with IMRT at our institution between January 2009 and August 2012 was performed. Hippocampal-sparing was defined as a mean dose to at least one hippocampus of less than 30 Gy. The dose delivered to the tumour was never compromised to achieve the hippocampal dose constraint. Logistic regression analyses were performed to identify predictive factors for achieving hippocampal-sparing treatment. Eighteen patients were identified and hippocampal-sparing was achieved in 14 (78%). The median dose prescribed was 59.4 Gy in 33 fractions and 11 patients had WHO grade III gliomas. The mean dose to the contralateral hippocampus was 24.9 Gy. Planning target volumes less than 420.5 cm3 were more likely to enable hippocampal-sparing treatment to be given (hazard ratio 1.7, p=0.03) and there was a trend with oligodendrogliomas and anaplastic oligodendrogliomas. Hippocampal-sparing radiotherapy is feasible in patients with WHO grade II and III gliomas. Oncologic outcomes are yet to be assessed prospectively. The relationship between hippocampal dose and neurocognitive function in adults is currently under investigation.

Results of a prospective study of positron emission tomography-directed management of residual nodal abnormalities in node-positive head and neck cancer after definitive radiotherapy with or without systemic therapy

BACKGROUND

The purpose of this study was to present our prospectively evaluated positron emission tomography (PET)-directed policy for managing the neck in node-positive head and neck squamous cell carcinoma (N+HNSCC) after definitive radiotherapy (RT) with or without concurrent systemic therapy.

METHODS

One hundred twelve consecutive patients who achieved a complete response at the primary site underwent a 12-week posttherapy nodal response assessment with PET and diagnostic CT. Patients with an equivocal PET underwent a repeat PET 4 to 6 weeks later. Patients with residual CT nodal abnormalities deemed PET-negative were uniformly observed regardless of residual nodal size.

RESULTS

Median follow-up from commencement of RT was 28 months (range, 13-64 months). Residual CT nodal abnormalities were present in 50 patients (45%): 41 PET-negative and 9 PET-positive. All PET-negative residual CT nodal abnormalities were observed without subsequent isolated nodal failure.

CONCLUSION

PET-directed management of the neck after definitive RT in node-positive HNSCC appropriately spares neck dissections in patients with PET-negative residual CT nodal abnormalities.