Improve the management of patients with skull bone metastases by means of helical tomotherapy

Abstract

The skeleton is the first and most common site of distant metastases in breast cancer patients. Tumor bone disease is responsible for a considerable morbidity and markedly decreases the quality of life of patients [1]. Although providing rapid and lasting pain relief in symptomatic bone metastases, external beam radiotherapy may be associated with treatment-induced morbidity, particularly in patients with multiple skull metastases. For those patients, conventional radiotherapy may be deleterious, delivering high radiation doses to critical organs such as eyes or brain and leading to potential subsequent progressive neurocognitive decline. Helical tomotherapy (HT) combines intensity modulated fan-beam radiotherapy with megavoltage computed tomography imaging for patient positioning [2]. Its availability has recently opened new fields of exploration for palliative radiotherapy due to its ability to tailor very sharp dose distributions around the target volumes. Here, we report an interesting case of palliative use of HT in a breast cancer patient with multiple skull bone metastases. In October 2007, a 76-year-old patient presented with acute left peripheral facial paralysis and inflammatory bone pain occurring at the left part of her face. She had a previous history of invasive ductal carcinoma with multiple bone metastases. The CT scan and the bone scintigraphy showed multiple lytic bone metastases of the skull, predominant in the fronto-temporo-parietal area, extending to the chin, as shown in Fig. 1a and d, respectively. The patient was referred for HT, delivering 20 Gy using 6 MV photons, at 4 Gy per daily fraction, total duration 5 days, in the planning target volume (PTV), concurrently with highdose corticoids. The patient was treated lying on her back. A customized mask was used for immobilization and patient positioning. The mean doses delivered to 20%, 40%, and 100% of the left eye were 7.5, 5, and 2.5 Gy, respectively. The mean doses delivered to 20%, 40%, and 100% of the right eye were 2.5, 2, and 1 Gy, respectively. The mean doses delivered to 20%, 40%, and 100% of the brain were 10, 6, and 2.5 Gy, respectively. No acute toxicity was observed.