Next‐generation sequencing reveals remarkable genetic stability in primary and corresponding recurrent intestinal‐type sinonasal adenocarcinoma

Background Recurrent intestinal‐type sinonasal adenocarcinoma (ITAC) can occur several years after primary treatment and with different histology. We aimed to clarify if such recurrences could be second primary tumors and to identify actionable mutations as targets for personalized treatment of recurrent ITAC. Methods Twelve pairs of primary and recurrent ITAC were histologically examined and analyzed by next‐generation sequencing. Results Histological differences between primary and recurrent tumor pairs were observed in five cases. Frequent mutations included TP53 , APC , TSC2 , ATM , EPHA2 , BRCA2 , LRP1B , KRAS , and KMT2B . There was 86% concordance of somatic mutations between the tumor pairs, while four cases carried additional mutations in the recurrence. Conclusions We found all cases to be clonal recurrences and not second primary tumors. Moreover, tumor pairs showed a remarkable genomic stability, suggesting that personalized treatment of a recurrence may be based on actionable molecular genetic targets observed in the primary tumor.