A case report of thoracic SMARCA4-deficient undifferentiated tumor associated with brain metastases

Thoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UT) were considered distinct from the traditional NSCLC with SMARCA4-deficient (SMARCA4-dNSCLC) in the 5th edition of the WHO classification of thoracic tumors in 2021. Due to the low incidence rate and the lack of sufficient research, clear treatment guidelines for SMARCA4-UT are currently lacking. We report a rare case of thoracic SMARCA4-deficient undifferentiated tumor with multiple brain metastases. Following treatment with cranial metastasis radiotherapy and systemic immunotherapy combined with chemotherapy, the lesions significantly decreased in size, and the patient's symptoms improved markedly. This article retrospectively analyzed the diagnosis and treatment process of a case of SMARCA4-UT and discussed therapeutic progress and future prospects. Given the limitations of current single-drug therapy, the combined use of immunotherapy, chemotherapy, and new target drugs is an essential choice and the future direction.