A 75-year-old man was diagnosed in June 2016 with right-sided pleural desmoplastic mesothelioma. He had a previous history of smoking and exposure to asbestos as well as substantial underlying cardiovascular comorbidity. Curative treatment was deemed not feasible. While awaiting palliative antitumoral treatment, the patient experienced impaired balance, severe rotational vertigo, nausea, and vomiting. Brain CT and MRI in July 2016 revealed a solitary 20-mm metastasis with slight surrounding edema in the left middle cerebellar peduncle and extending along the tentorium (M1). V4 was minimally compressed without hydrocephalus. Corticosteroid therapy was initiated but microsurgery was deemed not feasible due to previous cardiovascular morbidity. Systemic palliative chemotherapy was initiated and he was referred for GKRS as no other treatment options remained available for M1. The patient underwent 3R-intervention for his solitary lesion in August 2016. KPS was estimated as 70–80 and RPA as 2 at GKRS 1 during steroid treatment de-escalation. KPS subsequently improved to 80 at GKRS 2 and 90–100 at GKRS 3 despite decreased steroid dose. M1 underwent a volume reduction of 22% between GKRS 1 and GKRS 3 (10.2 cm3 to 7.9 cm3) while V4 volume increased from 0.79 cm3 to 0.93 cm3 (21%). One-month follow-up with clinical assessment and MRI revealed mild fatigue presumed due to ongoing systemic antitumoral treatment (KPS 90) though without major neurological impairment, and substantial tumor volume reduction of almost 50% (10.2 cm3 at GKRS 1 to 5.6 cm3 at 4 weeks after GKRS 3). V4 volume had also increased significantly (from 0.79 cm3 at GKRS 1 to 1.31 cm3 at 4 weeks) []. A follow-up MRI at 3 months showed a small suspected recurrence with mild surrounding edema at the inferior aspect of the previous radiation field which was successfully treated in December 2016 along with ten new metastases; all eleven lesions were treated with SF-GKRS. No clinical signs of neurological deficits or radiological evidence of ARE were reported. The patient died 6 months after completion of 3R due to an aggressive, drug-resistant pneumonia.
A 62-year-old female patient was diagnosed in 2005 with ovarian carcinoma. She underwent surgery, several lines of antitumoral treatment, and regional fractionated radiotherapy prior to developing metastases to regional lymph nodes as well as peritoneal carcinomatosis (2008). In January 2016, the patient presented with 2-week history of nausea, vomiting, impaired balance and speech, severe swallowing difficulties, and sensory symptoms. The brain MRI demonstrated a large, solitary, 20-mm metastasis in the upper part of the medulla oblongata (M1) without significant perilesional edema, yet compressing the foramina of Luschka and Magendie with signs of mild hydrocephalus []. Corticosteroid therapy was initiated shortly thereafter. Microsurgical removal/debulking of the metastasis were deemed not feasible and 3R was offered after multidisciplinary in-hospital discussion. At the time of GKRS 1 in February 2016, KPS was estimated to be 60 and RPA 3. The corresponding dose fractionation schedule is described in . No tumor volume reduction or V4 decompression was noted between GKRS 1 and GKRS 3. A follow-up MRI at 4 weeks revealed a 54% decrease in the size of M1 (4.8 cm3 at GKRS 1 to 2.2 cm3 at follow-up). V4 volume increased (1.56 cm3 at GKRS 1 to 2 cm3 at follow-up), and the foramina of Luschka and Magendie were less compressed []. There was no evidence of hydrocephalus. The patient's neurological condition also improved dramatically at this time and KPS was estimated to be 70. The dysphagia, nausea, and vomiting disappeared, and she could articulate much better. Nevertheless, no considerable improvement in balance was reported. The patient continued systemic antitumoral treatment. Consecutive, initially monthly and later bimonthly radiological follow-ups until September 2016 (7 months after 3R) showed further volume decrease of M1. However, the patient developed mild radiation-induced perilesional edema (assessed as ARE) 5 months after treatment which slowly progressed until her last MRI at 7 months (September 2016) though without evidence of hydrocephalus. At this time, the patient was experiencing mild facial numbness almost solely limited to her right cheek and the right side of the jaw. The patient was also experiencing some more fatigue and balance impairment than usual although it was difficult to assess whether it was caused by the lesion itself and/or other factors such as aggressive systemic tumor progression, ongoing systemic treatment, and steroids. Nevertheless, despite the presence of perilesional edema, we assessed her neurological status and quality of life in relation to M1 as stable. She died 7 months after completion of 3R-treatment due to aggressive extracranial tumor disease progression.