Carotic blowout syndrome
Carotid blowout syndrome in pharyngeal cancer patients treated by hypofractionated stereotactic re-irradiation using CyberKnife: A multi-institutional matched-cohort analysis

https://doi.org/10.1016/j.radonc.2015.02.021Get rights and content

Abstract

Background and purpose

Although reirradiation has attracted attention as a potential therapy for recurrent head and neck tumors with the advent of modern radiotherapy, severe rate toxicity such as carotid blowout syndrome (CBOS) limits its potential. The aim of this study was to identify the risk factors of CBOS after hypofractionated stereotactic radiotherapy (SBRT).

Methods and patients

We conducted a matched-pair design examination of pharyngeal cancer patients treated by CyberKnife reirradiation in four institutes. Twelve cases with CBOS were observed per 60 cases without CBOS cases. Prognostic factors for CBOS were analyzed and a risk classification model was constructed.

Results

The median prescribed radiation dose was 30 Gy in 5 fractions with CyberKnife SBRT after 60 Gy/30 fractions of previous radiotherapy. The median duration between reirradiation and CBOS onset was 5 months (range, 0–69 months). CBOS cases showed a median survival time of 5.5 months compared to 22.8 months for non-CBOS cases (1-year survival rate, 36% vs.72%; p = 0.003). Univariate analysis identified an angle of carotid invasion of >180°, the presence of ulceration, planning treatment volume, and irradiation to lymph node areas as statistically significant predisposing factors for CBOS. Only patients with carotid invasion of >180° developed CBOS (12/50, 24%), whereas no patient with tumor involvement less than a half semicircle around the carotid artery developed CBOS (0/22, 0%, p = 0.03). Multivariate Cox hazard model analysis revealed that the presence of ulceration and irradiation to lymph nodes were statistically significant predisposing factors. Thus, we constructed a CBOS risk classification system: CBOS index = (summation of risk factors; carotid invasion >180°, presence of ulceration, lymph node area irradiation). This system sufficiently separated the risk groups.

Conclusion

The presence of ulceration and lymph node irradiation are risk factors of CBOS. The CBOS index, including carotid invasion of >180°, is useful in classifying the risk factors and determining the indications for reirradiation.

Section snippets

Materials and methods

The medical records of patients who underwent CyberKnife SBRT (Accuray; Sunnyvale, CA, USA) at four hospitals (Soseikai General Hospital, Osaka University Hospital, Fujimoto Hayasuzu Hospital, and Okayama Kyokuto Hospital) during 2000–2010 were reviewed for inclusion into the study. Among the 209 head and neck cancer patients who received reirradiation for residual, recurrent, or secondary malignancies, those with recurrent pharyngeal tumors adjacent to the carotid artery were included in this

Results

The median follow up time for the surviving patients after SBRT was 21 months (range, 6–122 months). No statistically significant deviation in sex, age, site, and treatment schedule was observed between the CBOS and non-CBOS cases (Table 1). The median duration between reirradiation and CBOS onset was 5 months (range, 0–69 months). There were significant differences in median survival time and 1-year survival rates between the CBOS and non-CBOS cases (5.5 vs. 22.8 months and 36% vs.72%; p = 0.005),

Discussion

CBOS is one of the most devastating complications of head and neck cancer. It generally occurs as a postoperative complication or when the tumor compromises the vascular axis [11]. CBOS is most common in patients who have previously received radiotherapy and/or underwent surgery [3], [12], and it also occurs after initial chemoradiation [11]. Other reported risk factors for CBOS are infection, pharyngocutaneous fistula formation, tumor progression, diffuse mucosal involvement/ulceration, and

Declaration of interests

We declare no competing interests.

Acknowledgement

We appreciate to Professor Satoshi Teramukai for his valuable assistance and supervision for statistical analyze. We also thank Enago (www.enago.jp) for the English language review.

References (21)

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