Retrospective cohort study of risk of relapse and efficacy of adjuvant chemotherapy in localized appendiceal adenocarcinoma

Relapse risk and benefit of adjuvant chemotherapy after resection of appendiceal adenocarcinoma (AA) are uncertain. A retrospective cohort study (January 2000 through February 2024; median follow-up 62.6 months) at MD Anderson Cancer Center (MDACC; Houston, TX) with validation from Memorial Sloan Kettering Cancer Center (MSKCC; New York, NY) investigated clinicopathologic and genomic factors associated with relapse and efficacy of adjuvant chemotherapy in localized AA. Participants were 439 patients with stage I to III AA from MDACC, of whom 202 underwent surgery and a validation cohort of 128 patients with stage II AA from MSKCC. The study found that relapse after resection was uncommon and lowest among goblet cell tumors. Lymph node involvement was associated with relapse, whereas other risk factors varied by histology. GNAS mutation was associated with relapse in nongoblet tumors, TP53 mutation was associated with relapse in goblet tumors, and adjuvant chemotherapy was not associated with improved relapse-free or overall survival in patients with stage II disease. The authors conclude that in this cohort study, risk of relapse following resection of localized AA was overall low but varied depending on histologic subtype and molecular features.