Hyperprogression of buccal squamous cell carcinoma accompanied by carotid sinus syndrome: A case report.

Buccal squamous cell carcinoma (BSCC) is a highly malignant oral cancer with high recurrence rates, poor prognosis, and significant mortality. Most patients are diagnosed at a locally advanced or metastatic stage, requiring a combination of treatments such as surgery, radiotherapy, chemotherapy, and immunotherapy. Hyperprogression refers to rapid tumor growth increased tumor burden, and worsening patient condition, representing a severe adverse effect of immunotherapy in BSCC is extremely rare, with limited salvage treatment options and poor prognosis. In October 2021, a locally advanced BSCC patient was treated at the Second Xiangya Hospital of Central South University. After undergoing radical surgery, the patient experienced rapid recurrence with cervical lymph node and bilateral lung metastases. Following two cycles of chemotherapy combined with immunotherapy, the primary buccal lesion, cervical lymph nodes, and pulmonary metastases significantly increased, indicative of hyperprogression. Concurrently, the patient developed carotid sinus syndrome, characterized by frequent bradycardia, hypotension, and altered consciousness, leading to an overall survival of 4 months. Understanding the causes and high-risk factors of hyperprogression and developing strategies for its prevention remain critical challenges in the era of cancer immunotherapy.