Amide proton transfer-weighted CEST MRI for radiotherapy target delineation of glioblastoma: a prospective pilot study.

BACKGROUND: Extensive glioblastoma infiltration justifies a 15-mm margin around the gross tumor volume (GTV) to define the radiotherapy clinical target volume (CTV). Amide proton transfer (APT)-weighted imaging could enable visualization of tumor infiltration, allowing more accurate GTV delineation. We quantified the impact of integrating APT-weighted imaging into GTV delineation of glioblastoma and compared two APT-weighted quantification methods-magnetization transfer ratio asymmetry (MTRasym) and Lorentzian difference (LD) analysis-for target delineation. METHODS: Nine glioblastoma patients underwent an extended imaging protocol prior to radiotherapy, yielding APT-weighted MTRasym and LD maps. From both maps, biological tumor volumes were generated (BTVMTRasym and BTVLD) and added to the conventional GTV to generate biological GTVs (GTVbio,MTRasym and GTVbio,LD). Wilcoxon signed-rank tests were performed for comparisons. RESULTS: The GTVbio,MTRasym and GTVbio,LD were significantly larger than the conventional GTV (p ≤ 0.022), with a median volume increase of 9.3% and 2.1%, respectively. The GTVbio,MTRasym and GTVbio,LD were significantly smaller than the CTV (p = 0.004), with a median volume reduction of 72.1% and 70.9%, respectively. There was no significant volume difference between the BTVMTRasym and BTVLD (p = 0.074). In three patients, BTVMTRasym delineation was affected by elevated signals at the brain periphery due to residual motion artifacts; this elevation was absent on the APT-weighted LD maps. CONCLUSION: Larger biological GTVs compared to the conventional GTV highlight the potential of APT-weighted imaging for radiotherapy target delineation of glioblastoma. APT-weighted LD mapping may be advantageous for target delineation as it may be more robust against motion artifacts. RELEVANCE STATEMENT: The introduction of APT-weighted imaging may, ultimately, enhance visualization of tumor infiltration and eliminate the need for the substantial 15-mm safety margin for target delineation of glioblastoma. This could reduce the risk of radiation toxicity while still effectively irradiating the tumor. TRIAL REGISTRATION: NCT05970757 (ClinicalTrials.gov). KEY POINTS: Integration of APT-weighted imaging into target delineation for radiotherapy is feasible. The integration of APT-weighted imaging yields larger GTVs in glioblastoma. APT-weighted LD mapping may be more robust against motion artifacts than APT-weighted MTRasym.

Rare central nervous system tumors in adults: a population-based study of ependymomas, pilocytic astrocytomas, medulloblastomas, and intracranial germ cell tumors.

Background: Ependymomas, pilocytic astrocytomas, medulloblastomas, and intracranial germ cell tumors occur relative frequently in children, but are rare central nervous system (CNS) tumors in adults. In this population-based survey, we established incidence, treatment, and survival patterns for these tumors diagnosed in adult patients (≥18 years) over a 30-year period (1989-2018). Methods: Data on 1384 ependymomas, 454 pilocytic astrocytomas, 205 medulloblastomas, and 112 intracranial germ cell tumors were obtained from the Netherlands Cancer Registry (NCR) on the basis of a histopathological diagnosis. For each tumor type, age-standardized incidence rates and estimated annual percentage change were calculated. Trends in incidence and main treatment modalities were reported per 5-year periods. Overall survival was calculated using the Kaplan-Meier method, and relative survival rates were estimated using the Pohar-Perme estimator. Results: Incidence and survival rates remained generally stable for pilocytic astrocytomas, medulloblastomas, and germ cell tumors. Increasing incidence was observed for spinal ependymomas, mostly for myxopapillary ependymomas, and survival improved over time for grade II ependymomas (P < .01). Treatment patterns varied over time with shifting roles for surgery in ependymomas and for chemotherapy and radiation in medulloblastomas and germinomas. Conclusions: The study provides baseline information for highly needed national and international standard treatment protocols, and thus for further improving patient outcomes in these rare CNS tumors.

Quality of life among patients with 4 to 10 brain metastases after treatment with whole-brain radiotherapy vs. stereotactic radiotherapy: a phase III, randomized, Dutch multicenter trial.

BACKGROUND: Stereotactic radiotherapy (SRT) is an attractive treatment option for patients with brain metastases (BM), sparing healthy brain tissue and likely controlling local tumors. Most previous studies have focused on radiological response or survival. Our randomized trial (NCT02353000) investigated whether quality of life (QoL) is better preserved using SRT than whole-brain radiotherapy (WBRT) for patients with multiple BM. Recently, we published our trial's primary endpoints. The current report discusses the study's secondary endpoints. METHODS: Patients with 4 to 10 BM were randomly assigned to a standard-arm WBRT (20 Gy in 5 fractions) or SRT group (1 fraction of 15-24 Gy or 3 fractions of 8 Gy). QoL endpoints-such as EQ5D domains post-treatment, the Barthel index, the European Organisation for Research and Treatment of Cancer (EORTC) questionnaires, and the neurocognitive Hopkins Verbal Learning Test-were evaluated. RESULTS: Due to poor accrual resulting from patients' and referrers' preference for SRT, this study closed prematurely. The other endpoints' results were published recently. Twenty patients were available for analysis (n=10 vs. n=10 for the two groups, respectively). Significant differences were observed 3 months post-treatment for the mobility (P=0.041), self-care (P=0.028), and alopecia (P=0.014) EQ5D domains, favoring SRT. This self-care score also persisted compared to the baseline (P=0.025). Multiple EORTC categories reflected significant differences, favoring SRT-particularly physical functioning and social functioning. CONCLUSIONS: For patients with multiple BM, SRT alone led to persistently higher QoL than treatment with WBRT. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02353000.

Fiducial marker motion relative to the tumor bed has a significant impact on PTV margins in partial breast irradiation.

INTRODUCTION: With the introduction of accelerated partial breast irradiation (APBI) and the trend of reducing the number of fractions, the geometric accuracy of treatment delivery becomes critical. APBI patient setup is often based on fiducials, as the seroma is frequently not visible on pretreatment imaging. We assessed the motion of fiducials relative to the tumor bed between planning CT and treatment, and calculated margins to compensate for this motion. METHODS: A cohort of seventy patients treated with APBI on a Cyberknife was included. Planning and in-room pretreatment CT scans were registered on the tumor bed. Residual motion of the centers of mass of surgical clips and interstitial gold markers was calculated. We calculated the margins required per desired percentage of patients with 100% CTV coverage, and the systematic and random errors for fiducial motion. RESULTS: For a single fraction treatment, a margin of 1.8 mm would ensure 100% CTV coverage in 90% of patients when using surgical clips for patient set-up. When using interstitial markers, the margin should be 2.2 mm. The systematic and random errors were 0.46 mm for surgical clip motion and 0.60 mm for interstitial marker motion. No clinical factors were found predictive for fiducial motion. CONCLUSIONS: Fiducial motion relative to the tumor bed between planning CT and APBI treatment is non-negligible and should be included in the PTV margin calculation to prevent geographical miss. Systematic and random errors of fiducial motion were combined with other geometric uncertainties to calculate comprehensive PTV margins for different treatment techniques.

Intrafraction motion during partial breast irradiation depends on treatment time.

INTRODUCTION: As the prognosis of early-stage breast cancer patients is excellent, prevention of radiation-induced toxicity has become crucial. Reduction of margins compensating for intrafraction motion reduces non-target dose. We assessed motion of the tumor bed throughout APBI treatment fractions and calculated CTV-PTV margins for breathing and drift. METHODS: This prospective clinical trial included patients treated with APBI on a Cyberknife with fiducial tracking. Paired orthogonal kV images made throughout the entire fraction were used to extract the tumor bed position. The images used for breathing modelling were used to calculate breathing amplitudes. The margins needed to compensate for breathing and drift were calculated according to Engelsman and Van Herk respectively. RESULTS: Twenty-two patients, 110 fractions and 5087 image pairs were analyzed. The margins needed for breathing were 0.3-0.6 mm. The margin for drift increased with time after the first imaging for positioning. For a total fraction duration up to 8 min, a margin of 1.0 mm is sufficient. For a fraction of 32 min, 2.5 mm is needed. Techniques that account for breathing motion can reduce the margin by 0.1 mm. There was a systematic trend in the drift in the caudal, medial and posterior direction. To compensate for this, 0.7 mm could be added to the margins. CONCLUSIONS: The margin needed to compensate for intrafraction motion increased with longer fraction duration due to drifting of the target. It doubled for a fraction of 24 min compared to 8 min. Breathing motion has a limited effect.

A Dutch phase III randomized multicenter trial: whole brain radiotherapy versus stereotactic radiotherapy for 4-10 brain metastases.

BACKGROUND: The clinical value of whole brain radiotherapy (WBRT) for brain metastases (BM) is a matter of debate due to the significant side effects involved. Stereotactic radiosurgery (SRS) is an attractive alternative treatment option that may avoid these side effects and improve local tumor control. We initiated a randomized trial (NCT02353000) to investigate whether quality of life is better preserved after SRS compared with WBRT in patients with multiple brain metastases. METHODS: Patients with 4-10 BM were randomized between the standard arm WBRT (total dose 20 Gy in 5 fractions) or SRS (single fraction or 3 fractions). The primary endpoint was the difference in quality of life (QOL) at 3 months post-treatment. RESULTS: The study was prematurely closed due to poor accrual. A total of 29 patients (13%) were randomized, of which 15 patients have been treated with SRS and 14 patients with WBRT. The median number of lesions were 6 (range: 4-9) and the median total treatment volume was 13.0 cc3 (range: 1.8-25.9 cc3). QOL at 3 months decreased in the SRS group by 0.1 (SD = 0.2), compared to 0.2 (SD = 0.2) in the WBRT group (P = .23). The actuarial 1-year survival rates were 57% (SRS) and 31% (WBRT) (P = .52). The actuarial 1-year brain salvage-free survival rates were 50% (SRS) and 78% (WBRT) (P = .22). CONCLUSION: In patients with 4-10 BM, SRS alone resulted in 1-year survival for 57% of patients while maintaining quality of life. Due to the premature closure of the trial, no statistically significant differences could be determined.

Reducing the Risk of Secondary Lung Cancer in Treatment Planning of Accelerated Partial Breast Irradiation.

Purpose: Adjuvant accelerated partial breast irradiation (APBI) results in low local recurrence risks. However, the survival benefit of adjuvant radiotherapy APBI for low-risk breast cancer might partially be offset by the risk of radiation-induced lung cancer. Reducing the lung dose mitigates this risk, but this could result in higher doses to the ipsilateral breast. Different external beam APBI techniques are equally conformal and homogenous, but the intermediate to low dose distribution differs. Thus, the risk of toxicity is different. The purpose of this study is to quantify the trade-off between secondary lung cancer risk and breast dose in treatment planning and to compare an optimal coplanar and non-coplanar technique. Methods: A total of 440 APBI treatment plans were generated using automated treatment planning for a coplanar VMAT beam-setup and a non-coplanar robotic stereotactic radiotherapy beam-setup. This enabled an unbiased comparison of two times 11 Pareto-optimal plans for 20 patients, gradually shifting priority from maximum lung sparing to maximum ipsilateral breast sparing. The excess absolute risks of developing lung cancer and breast fibrosis were calculated using the Schneider model for lung cancer and the Avanzo model for breast fibrosis. Results: Prioritizing lung sparing reduced the mean lung dose from 2.2 Gy to as low as 0.3 Gy for the non-coplanar technique and from 1.9 Gy to 0.4 Gy for the coplanar technique, corresponding to a 7- and 4-fold median reduction of secondary lung cancer risk, respectively, compared to prioritizing breast sparing. The increase in breast dose resulted in a negligible 0.4% increase in fibrosis risk. The use of non-coplanar beams resulted in lower secondary cancer and fibrosis risks (p < 0.001). Lung sparing also reduced the mean heart dose for both techniques. Conclusions: The risk of secondary lung cancer of external beam APBI can be dramatically reduced by prioritizing lung sparing during treatment planning. The associated increase in breast dose did not lead to a relevant increase in fibrosis risk. The use of non-coplanar beams systematically resulted in the lowest risks of secondary lung cancer and fibrosis. Prioritizing lung sparing during treatment planning could increase the overall survival of early-stage breast cancer patients by reducing mortality due to secondary lung cancer and cardiovascular toxicity.

Injection of radiopaque hydrogel at time of lumpectomy improves the target definition for adjuvant radiotherapy.

BACKGROUND AND PURPOSE: During oncoplastic breast-conserving surgery (BCS), the surgical cavity is closed to reduce seroma formation. This makes the radiotherapy target definition using clips challenging, leading to poor inter-observer agreement and potentially geographical misses. We hypothesize that injecting a radiopaque hydrogel in the lumpectomy cavity before closure improves radiotherapy target definition and agreement between observers. MATERIALS AND METHODS: Women undergoing BCS in a single university hospital were prospectively accrued in the study. Three to 9 ml of iodined PolyEthylene Glycol (PEG) hydrogel and clips were inserted in the lumpectomy cavity. A CT-scan was performed at 4 to 6 weeks. CT images of BCS patients with standard clips only were used as control group, matched on age, specimen weight, and distance between clips. Six radiation oncologists delineated the tumor bed volumes and rated the cavity visualization scores (CVS). The primary endpoint was the agreement between observers measured using a Conformity Index (Cx). RESULTS: Forty-two patients were included, 21 hydrogel procedures and 21 controls, resulting in 315 observer pairs. The feasibility of the intervention was 100%. The median Cx was higher in the intervention group (Cx = 0.70, IQR [0.54-0.79]) than in the control group (Cx = 0.54, IQR [0.42-0.66]), p < 0.00, as were the CVS (3.5 [2.5-4.5] versus 2.5 [2-3.5], p < 0.001). The rate of surgical site infections was similar to literature. CONCLUSIONS: The use of radiopaque PEG enables to identify the lumpectomy cavity, resulting in a high inter-observer agreement for radiotherapy target definition. This intervention is easy to perform and blend well into current practice.

Incidence of pseudoprogression in low-grade gliomas treated with radiotherapy.

Background: As the incidence of pseudo-progressive disease (psPD), or pseudoprogression, in low-grade glioma (LGG) is unknown, we retrospectively investigated this phenomenon in a cohort of LGG patients given radiotherapy (RT). Methods: All MRI scans and clinical data from patients with histologically proven LGG treated with radiation between 2000 and 2011 were reviewed. PsPD was scored when a new enhancing lesion occurred after RT and subsequently disappeared or remained stable for at least a year without therapy, including dexamethasone. Results: Sixty-three out of 71 patients who received RT for LGG were deemed eligible for evaluation of psPD. The median follow-up was 5 years (range 1‒10 y). PsPD was seen in 13 patients (20.6%). PsPD occurred after a median of 12 months with a range of 3-78 months. The median duration of psPD was 6 months, with a range of 2-26 months and always occurred within the RT high dose fields of at least 45 Gy. The area of the enhancement at the time of psPD was significantly smaller compared with the area of enhancement during "true" progression (median size 54mm2 [range 12-340mm2] vs 270mm2 [range 30-3420mm2], respectively; P = .009). Conclusions: PsPD occurs frequently in LGG patients receiving RT. This supports the policy to postpone a new line of treatment until progression is evident, especially when patients have small contrast enhancing lesions within the RT field.

Multimodality treatment for anaplastic thyroid carcinoma--treatment outcome in 75 patients.

PURPOSE: To retrospectively analyze the outcome of patients with anaplastic thyroid carcinoma (ATC) treated in the Erasmus MC. MATERIAL AND METHODS: Seventy-five ATC-patients were treated between 1972 and 2003. Mean age was 68 years. Tumor stage was IVA in 9%, IVB in 51%, and IVC in 40%. Thirty-six patients underwent up-front surgery, with 53% resulting in R0/R1 resection. Before 1988 adjuvant treatment consisted of conventional radiotherapy (RT) and/or chemotherapy (CT). As of 1988, 30 eligible patients were enrolled in a newly designed protocol. This consists of locoregional RT in 46 fractions of 1.1 Gy, given twice daily, followed by prophylactic irradiation of the lungs (PLI) in 5 daily fractions of 1.5 Gy. During radiation, low-dose Doxorubicine (15 mg/m(2)) is administered weekly and is followed by adjuvant Doxorubicine (50 mg/m(2)) 3-weekly up to a cumulative dose of 550 mg/m(2). Twenty-five ineligible patients were treated conventionally. RESULTS: Overall median survival was 3 months, 1-year OS 9%. Locoregional control was significantly higher in patients who had undergone R0/R1 resection or chemoradiation, with best results for patients who underwent both (complete remission in 89%). However, the survival benefit of patients who reached CR remained borderline (median OS 7 months, 1-year OS 32%). Three patients survived for more than 5 years; all had undergone R0/R1 surgical resection and chemoradiation. Acute toxicity in the protocol group was significantly higher than in the nonprotocol group, with 46% versus 11% grade 3 pharyngeal and/or esophageal toxicity. CONCLUSION: Despite the ultimately dismal prognosis of ATC-patients, multimodality treatment significantly improved local control and improved the median survival.

Incidence of early pseudo-progression in a cohort of malignant glioma patients treated with chemoirradiation with temozolomide.

BACKGROUND: Radiotherapy (RT) plus concomitant and adjuvant temozolomide (TMZ) is now the standard of care for patients with newly diagnosed glioblastoma. The occurrence of pseudo-progression directly after RT is a recognized phenomenon, but to the authors' knowledge its incidence after combined RT/TMZ is unknown. The occurrence of early pseudo-progression was retrospectively assessed in a cohort of malignant glioma patients treated with RT/TMZ. METHODS: The pre-RT and post-RT brain scans from patients treated with RT/TMZ for a malignant glioma were reviewed. Scans were made before the start of RT, 4 weeks after the end of RT, and every 3 months thereafter. In addition, information was collected regarding clinical signs and symptoms, dexamethasone dose, histology, and survival. RESULTS: Eighty-five patients were identified. In 36 patients (42%) the first follow-up scan 4 weeks after the end of RT indicated disease progression. Of these 36 patients, 18 (50%) were diagnosed with pseudo-progression. None of the patients received additional treatment other than TMZ. Six of 18 patients with pseudo-progression and 12 of the 18 patients with real tumor progression developed new clinical signs and symptoms during RT or in the first 4 weeks thereafter. CONCLUSIONS: Up to 50% of malignant glioma patients treated with RT/TMZ and progression immediately after RT develop pseudo-progression. The current study data support the idea to continue TMZ in the case of progressive lesions immediately after RT/TMZ. Surgery should be considered in symptomatic cases. The inclusion of patients with progressive lesions developing directly after chemoradiation in studies regarding recurrent gliomas will lead to an overestimation of the results.