Loss of cervical spinal curvature during radiotherapy for head-and-neck cancers: The neck moves, too

Purpose: We became concerned about our observation of the loss of the normal lordotic cervical spinal curvature during the course of radiotherapy (RT) for head-and-neck tumors. Our goal was to evaluate formally the cervical lordotic curve in 50 random patients by comparing the cervical spinal angles (CSAs) measured at the initiation of RT with the CSAs measured during the last week of RT. Methods and Materials: Fifty patients treated mono-isocentrically for head-and-neck cancer were selected randomly for review. All patients had custom-made masks, shoulder pulls, and multiple tattoos to ensure reproducibility. The CSA was defined as the angle formed by the line projected parallel to the posterior surface of C2 and the line projected parallel to C6. The measurements were done on the simulation film and the first and last port films. Results: The average decrease in the CSA was 2.26° (SD ±2.19°). In patients with the isocenter placed as low as possible, the change was significantly more compared with the remaining population. (3.8° vs. 1.7°, p = 0.004). Conclusion: Despite customized immobilization, the neck position changes during the course of RT for head-and-neck tumors. Patients with the isocenter placed very low have the least long-term reproducibility and a comfortable position may be best suited to intensity-modulated RT for such head-and-neck cancer patients.