Establishing Novel Molecular Subtypes of Appendiceal Cancer

Mary Garland-Kledzik, Anthony Scholer, Miquel Ensenyat-Mendez, Javier I.J. Orozco, Adam Khader, Juan Santamaria-Barria, Trevan Fischer, Alessio Pigazzi, Diego M. Marzese

Research output: Contribution to journalArticlepeer-review

Abstract

PURPOSE: Appendiceal cancer is a rare disease process with complex treatment strategies. The objective of this study was to identify mutation-based genetic subtypes that may differ from the current histological classification, compare the genetic make-up of primaries and metastases, and find novel targetable alterations. METHODS: The analyses involved the curation and normalization of gene mutation panels from appendiceal adenocarcinoma and mucinous adenocarcinoma (n = 196) stored in the AACR GENIE Database v6.0. Genes mutated in less than one patient and tumors profiled with incomplete mutation panels were excluded from the study. The optimal number of AC subtypes was established using the Nonnegative Matrix Factorization algorithm. Statistical comparisons of mutation frequencies were performed using Pearson's χ2 test. RESULTS: AC patients were stratified into five mutation subtypes, based on a final set of 41 cancer-related genes. AC0 had no mutations. The most frequently mutated genes varied between the subtypes were: AC1: KRAS (91.9%) and GNAS (77.4%); AC2: KRAS (52.5%), APC (32.5%), and GNAS (30%); AC3: KMT2D (38.7%), TP53 (38.7%), KRAS (35.5%), EP300 (22.6%); and AC4: TP53 (97.2%), KRAS (77.8%), and SMAD4 (36.1%). Additionally, AC3 was less likely to be mucinous (22.6% vs. 50.0-74.2%, p < 0.001) and had a higher mutation frequency (3.6 vs. 0-3.1, p < 0.001). There were no significant differences between primary tumors and metastases in the 41 assessed genes (p = 0.35). CONCLUSIONS: The characterization of these subtypes suggests a need for molecular approaches to complement anatomical and histopathological staging for AC. A prospective comparison of subtype prognosis and response to surgery and adjuvant treatment is needed to identify the clinical applications of the novel molecular subtypes.

Original languageEnglish (US)
Pages (from-to)2118-2125
Number of pages8
JournalAnnals of Surgical Oncology
Volume29
Issue number3
DOIs
StatePublished - Mar 1 2022
Externally publishedYes

ASJC Scopus subject areas

  • Surgery
  • Oncology

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