Cochlear-optimized treatment planning in photon and proton radiosurgery for vestibular schwannoma patients.

Objective: To investigate the potential to reduce the cochlear dose with robotic photon radiosurgery or intensity-modulated proton therapy planning for vestibular schwannomas. Materials and Methods: Clinically delivered photon radiosurgery treatment plans were compared to five cochlear-optimized plans: one photon and four proton plans (total of 120). A 1x12 Gy dose was prescribed. Photon plans were generated with Precision (Cyberknife, Accuray) with no PTV margin for set-up errors. Proton plans were generated using an in-house automated multi-criterial planning system with three or nine-beam arrangements, and applying 0 or 3 mm robustness for set-up errors during plan optimization and evaluation (and 3 % range robustness). The sample size was calculated based on a reduction of cochlear Dmean > 1.5 Gy(RBE) from the clinical plans, and resulted in 24 patients. Results: Compared to the clinical photon plans, a reduction of cochlear Dmean > 1.5 Gy(RBE) could be achieved in 11/24 cochlear-optimized photon plans, 4/24 and 6/24 cochlear-optimized proton plans without set-up robustness for three and nine-beam arrangement, respectively, and in 0/24 proton plans with set-up robustness. The cochlea could best be spared in cases with a distance between tumor and cochlea. Using nine proton beams resulted in a reduced dose to most organs at risk. Conclusion: Cochlear dose reduction is possible in vestibular schwannoma radiosurgery while maintaining tumor coverage, especially when the tumor is not adjacent to the cochlea. With current set-up robustness, proton therapy is capable of providing lower dose to organs at risk located distant to the tumor, but not for organs adjacent to it. Consequently, photon plans provided better cochlear sparing than proton plans.

Progression of hearing loss after LINAC-based stereotactic radiotherapy for vestibular schwannoma is associated with cochlear dose, not with pre-treatment hearing level.

BACKGROUND: Although stereotactic radiotherapy (SRT) for vestibular schwannoma has demonstrated excellent local control rates, hearing deterioration is often reported after treatment. We therefore wished to assess the change in hearing loss after SRT and to determine which patient, tumor and treatment-related factors influence deterioration. METHODS: We retrospectively analyzed progression of hearing loss in patients with vestibular schwannoma who had received stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) as a primary treatment between 2000 and 2014. SRS had been delivered as a single fraction of 12 Gy, and patients treated with FSRT had received 30 fractions of 1.8 Gy. To compare the effects of SRS and FSRT, we converted cochlear doses into EQD2. Primary outcomes were loss of functional hearing, Gardner Robertson (GR) classes I and II, and loss of baseline hearing class. These events were used in Kaplan Meier plots and Cox regression. We also calculated the rate of change in Pure Tone Average (PTA) in dB per month elapsed after radiation-a measure we use in linear regression-to assess the associations between the rate of change in PTA and age, pre-treatment hearing level, tumor size, dose scheme, cochlear dose, and time elapsed after treatment (time-to-first-audiogram). RESULTS: The median follow-up was 36 months for 67 SRS patients and 63 months for 27 FSRT patients. Multivariate Cox regression and in linear regression both showed that the cochlear V90 was significantly associated with the progression of hearing loss. But although pre-treatment PTA correlated with rate of change in Cox regression, it did not correlate in linear regression. The time-to-first-audiogram was also significantly associated, indicating time dependency of the rate of change. None of the analysis showed a significant difference between dose schemes. CONCLUSIONS: We found no significant difference between SRS and FSRT. As the deterioration in hearing after radiotherapy for vestibular schwannoma was associated with the cochlea V90, restricting the V90 may reduce progression of hearing loss. The association between loss of functional hearing and baseline PTA seems to be biased by the use of a categorized variable for hearing loss.

Identifying at diagnosis the vestibular schwannomas at low risk of growth in a long-term retrospective cohort.

OBJECTIVES: Identification at time of diagnosis of those vestibular schwannomas that will not grow. DESIGN: Retrospective cohort study of consecutive patients diagnosed with a sporadic vestibular schwannoma that were entered in the wait-and-scan protocol. SETTING: Academic referral centre. PARTICIPANTS: The study group contained 155 patients with a sporadic vestibular schwannoma first seen in the full 8-year period 2000-2007: continual wait-and-scan (n = 89) and initial wait-and-scan until intervention (n = 66). MAIN OUTCOME MEASURES: Tumour growth, defined as more than 2 mm linear difference in any plane between the diagnostic MRI-scan and the last available scan, was related to clinical parameters at diagnosis: localisation of the tumour (solely intracanalicular versus cisternal extension), sudden sensorineural hearing loss, sensorineural hearing loss longer than 2 years and vertigo/instability. RESULTS: Hearing loss longer than 2 years and an entirely intracanalicular localisation were associated with no tumour growth by univariate and multivariate Cox analysis. Combining both factors at time of diagnosis resulted in a group with low risk of growth (n = 36, median follow-up of 6.2 years) with a Hazard Ratio for growth of 0.37 (95% CI, 0.19-0.69). This subgroup is about 25% of the wait-and-scan population. Thirty-one percent showed growth, while in the remaining higher risk group of 119 patients 62% showed growth. For the growing schwannomas, the median time for growth becoming manifest is 1.9 years after diagnostic MRI. CONCLUSIONS: In this study on vestibular schwannoma patients that start in a wait-and-scan protocol, about a quarter may be set apart having a low risk for growth. These patients at diagnosis combine a history of hearing loss longer than 2 years and a fully intracanalicular schwannoma. They seem to be not needed yearly MRI checks.

Hepatocellular carcinoma: Dutch guideline for surveillance, diagnosis and therapy.

UNLABELLED: Hepatocellular carcinoma (HCC) is rare in the Netherlands, even though the incidence has increased quite sharply in recent years. Standard treatment options consist of surgery, orthotopic liver transplantation, radiofrequency ablation, transarterial chemoembolisation (TACE) and systemic therapy with sorafenib. The consensus-based Dutch HCC guideline, established in 2013, serves to guide surveillance, diagnosis and treatment options: Surveillance should be performed by ultrasound at six-month intervals in well-defined cirrhotic patients and in selected high-risk hepatitis B carriers; A nodule > 1 cm in cirrhotic patients with arterial hypervascularity and venous or delayed phase washout at four-phase CT or MRI scan establishes the diagnosis of HCC; In patients with HCC without underlying cirrhosis, resection should be considered regardless of tumour size; In cirrhotic HCC patients, tumour stage, severity of underlying cirrhosis, and performance status determine treatment options. The algorithm of the Barcelona Clinic Liver Cancer (BCLC) staging system should be followed; Patients with Child-Pugh A-B cirrhosis (CP < 8 points) and performance status 0-2 are candidates for any active treatment other than transplantation; In early stage HCC (BCLC stage 0 or A, compensated cirrhosis without portal hypertension) surgical resection, liver transplantation, or radiofrequency ablation should be considered; In intermediate stage HCC (BCLC stage B) TACE and÷ or radiofrequency ablation should be considered; In advanced stage HCC (BCLC stage C) sorafenib should be considered. CONCLUSION: The Dutch HCC guideline offers advice for surveillance, diagnosis and treatment of HCC.

Treatment precision of image-guided liver SBRT using implanted fiducial markers depends on marker-tumour distance.

The purpose of this study is to assess the accuracy of day-to-day predictions of liver tumour position using implanted gold markers as surrogates and to compare the method with alternative set-up strategies, i.e. no correction, vertebrae and 3D diaphragm-based set-up. Twenty patients undergoing stereotactic body radiation therapy (SBRT) with abdominal compression for primary or metastatic liver cancer were analysed. We determined the day-to-day correlation between gold marker and tumour positions in contrast-enhanced CT scans acquired at treatment preparation and before each treatment session. The influence of marker-tumour distance on the accuracy of prediction was estimated by introducing a method extension of the set-up error paradigm. The distance between gold markers and the centre of the tumour varied between 5 and 96 mm. Marker-guidance was superior to guiding treatment using other surrogates, although both the random and systematic components of the prediction error SD depended on the tumour-marker distance. For a marker-tumour distance of 4 cm, we observed σ = 1.3 mm and Σ = 1.6 mm. The 3D position of the diaphragm dome was the second best predictor. In conclusion, the tumour position can be predicted accurately using implanted markers, but marker-guided set-up accuracy decreases with increasing distance between implanted markers and the tumour.

Stereotactic body radiation therapy for colorectal liver metastases.

BACKGROUND: Stereotactic body radiation therapy (SBRT) is a treatment option for colorectal liver metastases. Local control, patient survival and toxicity were assessed in an experience of SBRT for colorectal liver metastases. METHODS: SBRT was delivered with curative intent to 20 consecutively treated patients with colorectal hepatic metastases who were candidates for neither resection nor radiofrequency ablation (RFA). The median number of metastases was 1 (range 1-3) and median size was 2.3 (range 0.7-6.2) cm. Toxicity was scored according to the Common Toxicity Criteria version 3.0. Local control rates were derived on tumour-based analysis. RESULTS: Median follow-up was 26 (range 6-57) months. Local failure was observed in nine of 31 lesions after a median interval of 22 (range 12-52) months. Actuarial 2-year local control and survival rates were 74 and 83 per cent respectively. Hepatic toxicity grade 2 or less was reported in 18 patients. Two patients had an episode of hepatic toxicity grade 3. CONCLUSION: SBRT is a treatment option for patients with colorectal liver metastases who are not candidates for resection or RFA.