Background and purpose: The goal of this work was to examine toxicity and risk factors after irradiation of the cervical spinal cord.
Patients and methods: A total of 437 patients irradiated for a laryngeal and oropharyngeal carcinoma were eligible (median follow-up 27 months). Spinal cord contouring was defined differently over time as anatomically defined spinal cord area (SCA) and the spinal cord on CT (SC) with a margin of 3 or 5 mm (SCP3/SCP5).
Results: None developed chronic progressive radiation myelopathy (CPRM) (maximum spinal dose 21.8-69 Gy); 3.9% (17/437) developed a Lhermitte sign (LS) with a median duration of 6 months (range 1-30 months) and was reversible in all patients. Risk factors for developing LS were younger age (52 vs. 61 years, p < 0.001), accelerated RT (12/17 patients, p < 0.005), and dose-volume relationships for SCA with ≥ 45 Gy of 14.15 cm(3) and 7.9 cm(3) for patients with and without LS, respectively.
Conclusion: LS is more frequently observed in younger patients and in patients treated with accelerated radiotherapy. A dose-volume relationship was seen for V45 in the case of SCA. For higher doses, no clear dose-volume relationships were observed.