Soft-tissue metastasis in esophageal cancer managed by dose escalation radiation therapy: a clinical case and review of literature

Soft tissue metastasis in esophageal cancer is a very rare entity. A 76-year-old man was referred for a week's history of dysphagia. Upper gastrointestinal endoscopy was performed, and biopsies were consistent with an adenocarcinoma of the lower esophagus. The patient was free of metastasis on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT). The patient was treated with pre-operative chemoradiation, followed by surgery. Intravenous carboplatin [area under the curve of 2 mg/mL/min (AUC2)] and intravenous paclitaxel 50 mg/m² with concurrent radiotherapy (RT) (45 Gy delivered in 25 fractions of 1.8 Gy per fraction) were introduced from May 31^st, 2021, to July 2^nd, 2021. Lewis-Santy subtotal esophagectomy was performed, and pathology revealed a ypT3 ypN0 (0/26) L0 V1 Pn1 G3 R0. Adjuvant nivolumab was introduced for a total of 12 months. After five months of nivolumab, the patient complained of a painful left shoulder subcutaneous tumefaction in routine evaluation. Biopsy of the deltoid muscle demonstrated a poorly differentiated adenocarcinoma consistent with esophageal metastasis. Additional skeletal muscle (one) and bone metastases (two) were revealed on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT). After multidisciplinary team approach, palliative radiation therapy to all metastases, denosumab and FOLFOX were introduced. Despite initial excellent clinical outcomes, patient presented avascular necrosis of left femoral head managed by surgery but died after post-operative complications. To the best of our knowledge, it is the first reported case with rare soft-tissue metastasis occurring during adjuvant nivolumab in esophageal cancer.