Clinicopathological and genetic analysis of primary intraosseous carcinoma not otherwise specified (PIOC NOS)

BACKGROUND: Primary intraosseous carcinoma not otherwise specified (PIOC NOS) is an extremely rare jawbone cancer, accounting for approximately 1-2% of all oral cancers. Considering its rarity, no established standard treatment exists for postoperative recurrence or metastasis. This study aimed to analyse the clinical manifestations of this disease and identify novel genomic abnormalities to aid identification of potential treatment strategies. METHODS: We examined the clinical information of 14 PIOC NOS cases treated at our institution in recent years and compared it with previous reports. Genomic analysis was conducted on seven formalin-fixed paraffin-embedded surgical specimens, assessing 523 DNA and 55 RNA cancer-related genes using next-generation sequencing. RESULTS: Our findings, along with previous literature, revealed the posterior mandible as the primary site in most cases, though this was rarely identified at the time of initial diagnosis. Recurrence within two years of surgery was common. Hotspot mutations in PIK3CA were observed in 60% of cases. Additionally, one patient had high TMB status. CONCLUSIONS: Given the challenges in diagnosis and the potential for rapid recurrence or metastasis, early detection is crucial. Comprehensive genomic profiling is highly desirable, as genomic analysis may direct the development of targeted therapeutic agents to treat relapse.