Glottic Web Formation During Radiation Therapy: First Case Report Compared With Radiation Dose

Introduction

The guidelines for larynx preservation recommend that early-stage (cT1-T2) glottic laryngeal cancer can be treated with radiation therapy. ¹ We report a patient with early-stage glottic cancer who developed anterior commissure web formation during the second half of chemoradiation therapy. Acquired laryngeal web formation usually occurs after traumatic events such as partial laryngectomy and burn injuries.

Case Report

A 63-year-old woman presented with a 1-year history of hoarseness. The patient worked in childcare and used her voice frequently. At the time of examination, laryngoscopy revealed white lesions, mainly in the both vocal folds and also in the anterior commissure and bilateral subglottic areas (Figure 1). Biopsy specimens obtained from the both vocal folds and bilateral subglottic areas showed moderately differentiated squamous cell carcinoma. There was no vocal fold fixation. Positron emission tomography revealed no evidence of either lymph node or distant metastasis. The patient was diagnosed with T2N0M0 glottic laryngeal cancer.

Figure 1.

Laryngoscopic examination showed white lesions mainly in the bilateral vocal cords and also in the anterior commissure and bilateral subglottic area.

Patients with T2N0M0 glottic cancer were treated with concurrent chemoradiation therapy with docetaxel at a dose of 10 mg/m² twice per week and have achieved good survival and laryngeal preservation rates with this approach. ² The present patient was treated with this protocol. The radiation therapy was delivered using opposed lateral fields with an X-ray beam energy of 4 MV, based on treatment planning with 3-dimensional computed tomography. The patient was extremely obese with a body mass index of 41 kg/m². Her neck was very thick, and there was a high-dose region that received 107% to 110% of the prescribed dose in the anterior half of the vocal folds. A field-in-field technique was used to reduce this high-dose region, although complete elimination was not possible (Figure 2).

Figure 2.

Radiation dose lines. The thick red line indicates the 110% isodose line and the thick yellow line the 107% isodose line of the prescribed dose.

At the point of receiving 52 Gy radiation, thin web formation was observed in the anterior commissure (Figure 3). The patient’s hoarseness subsequently worsened further, but her vocal fold mobility was preserved. Radiation therapy was delivered up to a total dose of 66 Gy.

Figure 3.

At the point of receiving 52 Gy radiation, there was a thin web formation and adhesion between the vocal cords, but vocal cord mobility was preserved.

Laryngoscopic examination performed 81 days after completion of radiation therapy showed preservation of vocal fold mobility but ongoing presence of the anterior commissure web. Therefore, the vocal cords were separated by web resection with scissors. The biopsy specimens were free of recurrence. At 307 days after surgery, there was recurrence of the web.

Conclusion

Glottic web formation should be considered a potential side effect of radiation therapy for glottic cancer in cases with a high-dose region in the vocal folds resulting from conditions such as extreme obesity, as in the present case.

Recent advances in radiation therapy techniques, and increasing numbers of reports on intensity-modulated radiation therapy (IMRT), aimed at reducing radiation dose to the carotid artery, ³ suggest that IMRT may reduce the high-dose regions in the vocal folds in situations such as that of the present case and possibly avoid the complication.