Fully-automated, CT-only GTV contouring for palliative head and neck radiotherapy.

Planning for palliative radiotherapy is performed without the advantage of MR or PET imaging in many clinics. Here, we investigated CT-only GTV delineation for palliative treatment of head and neck cancer. Two multi-institutional datasets of palliative-intent treatment plans were retrospectively acquired: a set of 102 non-contrast-enhanced CTs and a set of 96 contrast-enhanced CTs. The nnU-Net auto-segmentation network was chosen for its strength in medical image segmentation, and five approaches separately trained: (1) heuristic-cropped, non-contrast images with a single GTV channel, (2) cropping around a manually-placed point in the tumor center for non-contrast images with a single GTV channel, (3) contrast-enhanced images with a single GTV channel, (4) contrast-enhanced images with separate primary and nodal GTV channels, and (5) contrast-enhanced images along with synthetic MR images with separate primary and nodal GTV channels. Median Dice similarity coefficient ranged from 0.6 to 0.7, surface Dice from 0.30 to 0.56, and 95th Hausdorff distance from 14.7 to 19.7 mm across the five approaches. Only surface Dice exhibited statistically-significant difference across these five approaches using a two-tailed Wilcoxon Rank-Sum test (p ≤ 0.05). Our CT-only results met or exceeded published values for head and neck GTV autocontouring using multi-modality images. However, significant edits would be necessary before clinical use in palliative radiotherapy.

Peptide receptor radionuclide therapy for metastatic paragangliomas.

There is little evidence to direct the management of malignant paragangliomas (mPGL) beyond initial surgical treatment. Peptide receptor radionuclide therapy (PRRT), using somatostatin analogues, is effective in other neuroendocrine tumours, but data on its efficacy in treating mPGL are scarce. We report safety and efficacy outcomes from a case series of five patients with advanced mPGLs treated with (177)Lu-DOTATATE PRRT. The mean age of our cohort was 34 years (range 16-47); 4 patients were male with bone disease being the most prevalent metastatic site. PRRT scheme varied between 1 and 4 cycles, with premature cessation due to suspected pneumonitis in one case and disease progression in another. Three patients with previously documented progressive disease achieved stabilization following treatment; one had partial response and one was treatment refractory. Median progression-free survival was 17 months (range 0-78 months). 177-Lu-DOTATATE is an effective therapy in mPGLs in this molecularly defined patient cohort, warranting further investigation in larger studies including hereditary and sporadic mPGL.