Vocal Cord Paralysis after Stereotactic Body Radiation Therapy to the Left Lung Apex

Todd J. Carpenter, Kenneth E. Rosenzweig
2014 Journal of Thoracic Oncology  
S tereotactic body radiotherapy (SBRT) is an effective treatment for early-stage inoperable non-small-cell lung cancer (NSCLC) with local control rates approaching 90% and acceptable rates of acute toxicity. 1 However, one of the tradeoffs of larger fraction sizes utilized is an increased risk of long-term toxicity to organs-at-risk, such as the lungs, central airway/bronchi, esophagus, heart, great vessels, spinal cord, brachial plexus, and chest wall. 2 Here, we report a case of vocal cord
more » ... alysis secondary to recurrent laryngeal nerve compression from radiation-induced fibrosis in a patient who received SBRT to a dose of 48 Gy in four fractions, 2 years and 9 months earlier. CASE REPORT An 85-year-old female with a 50+ pack-year smoking history was found to have a 3.3 cm left upper lobe lesion and a 0.8 cm right middle lobe lesion on chest computed tomography (CT). Positron emission tomography/CT demonstrated no evidence of metastatic disease. CT-guided biopsies, demonstrated TTF-1-positive adenocarcinoma. She was not a surgical candidate secondary to poor pulmonary function. The patient was treated with SBRT to both lesions consecutively to a dose of 4800 cGy in four fractions treated every other day utilizing a 6-field fixed-angle intensity modulated radiotherapy plan. Daily 2DkV and cone beam CT images were obtained before each treatment, and typical normal tissue constraints were observed (Fig. 1A,B) . The patient tolerated treatment without any significant toxicity. Routine follow-up did not reveal any late toxicity and surveillance CT imaging demonstrated stable post-treatment changes. Recently, 2 years and 9 months after treatment, the patient experienced new-onset hoarseness. Flexible laryngoscopy revealed total paralysis of the left vocal cord in the paramedian position. A repeat CT scan again demonstrated a stable 4.7 × 2.2 cm masslike consolidation in the left upper lobe corresponding to the patient's treatment field (Fig. 1C,D) . DISCUSSION One particular challenge with any emerging treatment modality is successfully defining organs-at-risk. Early experience revealed an unexpected 11-fold increased risk of grade 3-5 toxicity for tumors within 2 cm of the main tracheobronchial tree. 2 Similarly, the importance of limiting chest wall dose was elucidated only after initial cases of chest wall pain and rib fracture after SBRT were reported. 3 Although sensory deficits (e.g., brachial plexopathy and chest wall pain) are recognized concerns when irradiating apical tumors, other forms of peripheral nerve damage, such as motor dysfunction, are less common. 4 The time course for radiation-induced damage to the recurrent laryngeal nerve after conventionally fractionated radiation is known to be highly variable and can occur up to 25 years after treatment. 5 This report of left recurrent laryngeal nerve damage occurring more than 2.5 years after SBRT highlights the importance of close long-term follow-up of patients treated with SBRT and the ongoing need to document and report unexpected toxicities to minimize their probability in the future. The optimal risk-adapted fractionation schemes for SBRT to centrally located lung tumors is currently being investigated by RTOG 0813. (http://www.rtog.org/ ClinicalTrials/ProtocolTable/StudyDetails.aspx?study=0813). REFERENCES 1. Timmerman R, Paulus R, Galvin J, et al. Stereotactic body radiation therapy for inoperable early stage lung cancer. JAMA 2010;303:1070-1076. 2. Timmerman R, McGarry R, Yiannoutsos C, et al. Excessive toxicity when treating central tumors in a phase II study of stereotactic body radiation therapy for medically inoperable early-stage lung cancer. J Clin Oncol 2006;24:4833-4839. 3. Mutter RW, Liu F, Abreu A, Yorke E, Jackson A, Rosenzweig KE. Dosevolume parameters predict for the development of chest wall pain after stereotactic body radiation for lung cancer. Int J Radiat Oncol Biol Phys 2012;82:1783-1790. 4. Forquer JA, Fakiris AJ, Timmerman RD, et al. Brachial plexopathy from stereotactic body radiotherapy in early-stage NSCLC: dose-limiting toxicity in apical tumor sites. Radiother Oncol 2009;93:408-413. 5. Johansson S, Löfroth PO, Denekamp J. Left sided vocal cord paralysis: a newly recognized late complication of mediastinal irradiation.
doi:10.1097/jto.0000000000000208 pmid:25436809 fatcat:oi5rgqrdwbghflu6git5ztjewy