Stereotactic radiotherapy for head and neck paragangliomas: How long should we wait for treatment response?

in Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology by Gozde Yazici, Alper Kahvecioglu, Sezin Yuce Sari, Gokhan Ozyigit, Demet Yildiz, Mustafa Cengiz

TLDR

  • Stereotactic radiotherapy (SRT) is a type of radiation therapy that uses high-energy beams of radiation to shrink tumors in the head and neck. The study found that TVR, which means the tumor gets smaller, happens in about 62% of cases. The study also found that TVR happens faster in patients who haven't had surgery before and who are followed up for longer periods. The study also found that the more radiation therapy a patient gets, the more likely they are to have TVR. Future research should focus on finding the best way to give radiation therapy to shrink tumors in the head and neck.

Abstract

Stereotactic radiotherapy (SRT) is an effective treatment for head & neck (H&N) paragangliomas. Nevertheless, the timeline for achieving a tumor-volume-reduction (TVR) remains unclear. Sixty-three cases with H&N paragangliomas received definitive SRT and were evaluated retrospectively. Statistical Package for the Social Sciences (SPSS) v23.0 (IBM, Armonk, NY, USA) was used for statistics. Sixty-eight lesions were irradiated, with glomus jugulotympanicum being the most common location (44 %). Median tumor diameter and volume were 3 cm (range, 1-7.6 cm) and 15.4 cm(range,1-185 cm), respectively. Median dose was 25 Gy (range, 12-37.5 Gy) in 5 fractions (range, 1-5 fractions). Median follow-up was 40 months (range, 3-184 months). Treatment response, evaluated at a median 4.6 months post-SRT (range: 3-11 months), revealed TVR in 26 cases (41 %). During follow-up, 13 additional cases showed TVR, resulting in an overall TVR rate of 62 %. The median duration for attaining TVR was 9 months (range, 3-36 months) after SRT, and TVR occurred ≥ 12 months in 42 % of cases. Patients without prior surgery (p = 0.03) and with a longer follow-up (p = 0.04) demonstrated a higher rate of TVR. The likelihood of TVR tends to increase as the SRT dose increases (p = 0.06). Overall local control (LC) rate was 100 %. No ≥ grade 3 acute or late toxicities were observed. While SRT demonstrates an excellent LC rate for H&N paragangliomas, it's important to note that the response to treatment may require time. TVR may last beyond the initial year of treatment in a substantial proportion of patients.

Overview

  • The study evaluates the effectiveness of stereotactic radiotherapy (SRT) for head & neck (H&N) paragangliomas and the timeline for achieving a tumor-volume-reduction (TVR).
  • Sixty-three cases with H&N paragangliomas received definitive SRT and were evaluated retrospectively. Statistical Package for the Social Sciences (SPSS) v23.0 was used for statistics. Sixty-eight lesions were irradiated, with glomus jugulotympanicum being the most common location (44%).
  • The primary objective of the study is to determine the TVR rate and the timeline for achieving TVR after SRT for H&N paragangliomas.

Comparative Analysis & Findings

  • The study compared the outcomes observed under different experimental conditions or interventions detailed in the study. The results showed that TVR occurred in 26 cases (41%). During follow-up, 13 additional cases showed TVR, resulting in an overall TVR rate of 62%.

Implications and Future Directions

  • The study's findings suggest that TVR may last beyond the initial year of treatment in a substantial proportion of patients. The study also found that patients without prior surgery and with a longer follow-up demonstrated a higher rate of TVR. The likelihood of TVR tends to increase as the SRT dose increases. Future research should focus on identifying the optimal dose and duration of SRT for achieving TVR in H&N paragangliomas.
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