deficiency: implications for non-small cell lung cancer and management strategies, with relevance to and distinctions from thoracic undifferentiated tumor.

In 2021, the fifth edition of the World Health Organization (WHO) classification of thoracic tumors introduced a new category, "Thoracic -deficient undifferentiated tumor", highlighting deficiency as a key molecular marker for classifying as "other pulmonary epithelial tumors". is a gene encoding a protein involved in chromatin remodeling, and approximately 8% of non-small cell lung cancer (NSCLC) patients exhibit deletions. These patients are more prone to drug resistance, early recurrence, and unfavorable clinical outcomes. Moreover, NSCLC patients with concomitant mutations may not benefit from currently available treatments, underscoring the distinctiveness of this subgroup. Thoracic -deficient undifferentiated tumors (-UT) represent distinct entities from -deficient non-small cell lung cancer (-dNSCLC). This distinction is supported by their divergent pathological characteristics, demographic profiles, and survival outcomes. NSCLC cases deficient in exhibit high malignancy, yet the precise biological mechanisms underlying this phenomenon remain under intensive investigation. Pathological examination and immunohistochemistry can effectively differentiate -UT from -dNSCLC. -UT typically manifests as adenocarcinoma or, more rarely, as squamous cell carcinoma with undifferentiated rhabdomyoblastic morphology. Therefore, elucidating the mechanisms underlying alterations in NSCLC and their regulatory roles in tumorigenesis and the microenvironment is crucial. This article aims to discuss the structure, biological functions, significance in NSCLC development, and emerging potential therapeutic strategies related to while providing clinical practice guidance for NSCLC patients with deletions.