Definitive Radiotherapy for Bilateral Carotid Body Tumors: A Case Report with 3.5 Years Follow-Up

Abstract

Carotid body tumours (CBTs) are rare, slow-growing neuroendocrine neoplasms arising at the carotid bifurcation, and bilateral disease is uncommon. This case report describes the use of definitive radiotherapy for bilateral Shamblin type II CBTs in a 60-year-old man presenting with gradually enlarging, painless bilateral neck swellings. Magnetic resonance imaging demonstrated masses measuring 44 × 42 × 35 mm on the left and 36 × 31 × 32 mm on the right, with intense contrast enhancement, flow voids, and bilateral encasement of the internal and external carotid arteries. Both tumours were treated with a forward intensity-modulated radiotherapy plan. A total dose of 50.4 Gy in 28 fractions was delivered over 5.5 weeks. During treatment, the patient developed Grade II skin reactions by the end of the fourth week and Grade II dysphagia by the end of the fifth week; both were managed conservatively. Follow-up continued for 3.5 years. The left-sided tumour decreased from 64.68 cc to 30.46 cc, corresponding to an approximately 53% reduction, while the right-sided tumour decreased from 35.71 cc to 5.6 cc, representing an approximately 84% reduction. No late side effects were observed up to 3 years after treatment. This case demonstrates sustained bilateral tumour regression after definitive radiotherapy with manageable acute toxicity and supports its consideration in carefully selected patients when surgical morbidity is a major concern.