Abstract
BackgroundExternal beam radiotherapy (EBRT) is the treatment of choice for irresectable meningioma. Due to the strong expression of somatostatin receptors, peptide receptor radionuclide therapy (PRRT) has been used in advanced cases. We assessed the feasibility and tolerability of a combination of both treatment modalities in advanced symptomatic meningioma.Methods10 patients with irresectable meningioma were treated with PRRT (177Lu-DOTA0,Tyr3 octreotate or - DOTA0,Tyr3 octreotide) followed by external beam radiotherapy (EBRT). EBRT performed after PRRT was continued over 5–6 weeks in IMRT technique (median dose: 53.0 Gy). All patients were assessed morphologically and by positron emission tomography (PET) before therapy and were restaged after 3–6 months. Side effects were evaluated according to CTCAE 4.0.ResultsMedian tumor dose achieved by PRRT was 7.2 Gy. During PRRT and EBRT, no side effects > CTCAE grade 2 were noted. All patients reported stabilization or improvement of tumor-associated symptoms, no morphologic tumor progression was observed in MR-imaging (median follow-up: 13.4 months). The median pre-therapeutic SUVmax in the meningiomas was 14.2 (range: 4.3–68.7). All patients with a second PET after combined PRRT + EBRT showed an increase in SUVmax (median: 37%; range: 15%–46%) to a median value of 23.7 (range: 8.0–119.0; 7 patients) while PET-estimated volume generally decreased to 81 ± 21% of the initial volume.ConclusionsThe combination of PRRT and EBRT is feasible and well tolerated. This approach represents an attractive strategy for the treatment of recurring or progressive symptomatic meningioma, which should be further evaluated.
Highlights
Positron emission tomography using 68 Ga-labelled somatostatin analogues (SSR-positron emission tomography (PET)) and single photon emission computed tomography (SPECT) using 111Inoctreotid are well established for imaging neuroendocrine tumors and have shown very promising results for the diagnostic work up and for target volume delineation in radiotherapy treatment planning of meningioma [8,9,10]
A high correlation was observed between the uptakes in PET and peptide receptor radionuclide therapy (PRRT) (Spearman’s rank test: P > 0.01)
No acute toxicities were observed during PRRT
Summary
While surgery is the mainstay in treatment of meningioma, external beam radiotherapy (EBRT) offers the only other curative option in meningioma management [1, 2].For benign (WHO Grade 1) tumors, recommended doses are generally 50–54 Gy in fractions of 1.8–2 Gy, alternatively single doses of 12–16 Gy are used in especially higher grade meningiomas (≥WHO II), large, irregular tumors in critical locations and recurrent tumors in both radiation-naive as well as previously irradiated regions would likely benefit from a highly conformal dose escalation without increasing dose to normal tissues [4, 5]In case of a recurrence after external radiotherapy, results of studies using pharmacological targeted approaches have been modest at best and are often associated with significant toxicities [6].A potential target for a specific and well tolerable therapy in advanced meningioma is the somatostatin receptor (SSR). Positron emission tomography using 68 Ga-labelled somatostatin analogues (SSR-PET) and single photon emission computed tomography (SPECT) using 111Inoctreotid are well established for imaging neuroendocrine tumors and have shown very promising results for the diagnostic work up and for target volume delineation in radiotherapy treatment planning of meningioma [8,9,10]. Since many tumors display a fairly strong expression of somatostatin receptors, “peptide receptor radionuclide therapy” (PRRT), which is well evaluated and commonly used in neuroendocrine tumors [11, 12], has already been used in advanced cases of meningioma showing promising results [13,14,15]. Methods: 10 patients with irresectable meningioma were treated with PRRT (177Lu-DOTA0,Tyr octreotate or DOTA0,Tyr octreotide) followed by external beam radiotherapy (EBRT).
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