Impact of genetic mutations on prognosis and chemotherapy efficacy in advanced appendiceal carcinoma: insights from the nationwide Japanese comprehensive genomic profiling test database.

Background: Appendiceal carcinoma (AC) is a rare malignancy and has distinct genomic features, but their impact on prognosis and chemotherapy efficacy requires further investigation.

Methods: This retrospective study analyzed patients with advanced AC from the Japanese nationwide comprehensive genomic profiling test database, the Center for Cancer Genomics and Advanced Therapeutics (C-CAT) database, focusing on genetic alterations and their associations with clinical outcomes.

Results: Of the 314 patients, the histological types Queryincluded adenocarcinoma (Ad) (51.9%), mucinous adenocarcinoma (MAd) (30.3%), goblet cell adenocarcinoma (12.4%), and signet-ring cell adenocarcinoma (5.4%). The most common mutations were KRAS (52.5%), TP53 (49.4%), SMAD4 (18.8%), and GNAS (17.2%). KRAS mutations were most frequent in MAd (68.4%) and Ad (58.9%), whereas TP53 mutations were mostly prevalent in Ad (62.6%). We classified patients into molecular subtypes based on the presence of mutations and analyzed differences in overall survival (OS) by molecular subtype. Patients with TP53-mutant (mut) dominant tumors (all TP53-mut) and KRAS-mut focused tumors (TP53-wild-type (wt)/GNAS-wt/KRAS-mut/any SMAD4) showed a poorer median OS compared with those with GNAS-mut focused tumors (TP53-wt/GNAS-mut/any KRAS /any SMAD4) (median 47.4 and 37.5 months vs. not reached; p = 0.01 and p = 0.01, respectively). TP53 mutation was associated with poor time to treatment failure and OS with the oxaliplatin-based regimen for first-line chemotherapy.

Conclusions: This study suggested that the genetic mutations influenced the prognosis and chemotherapy efficacy in AC.