Appendiceal Adenocarcinoma Is Not Colon Cancer: JAMA Surgery | September 2026

What Did the Study Find?

This large study evaluated 439 patients with stage I–III appendiceal adenocarcinoma, with external validation and median follow-up exceeding 5 years.

Relapse after curative surgery was relatively uncommon: 9.4% overall and 9.7% at 5 years.

Recurrence varied markedly by histology—lowest with goblet cell (3%) and higher with mucinous (14%) and enteric-type tumours (17.5%).

Stage III disease and T4 tumours carried greater relapse risk.

Traditional colorectal cancer risk factors, including poor differentiation, perforation and lymphovascular/perineural invasion, did not consistently predict recurrence.

Adjuvant chemotherapy was not associated with improved recurrence-free or overall survival after adjustment.

Molecular profiling further refined risk: GNAS mutations in nongoblet and TP53 mutations in goblet tumours predicted relapse.

Why Does It Matter?

Current management often extrapolates from colorectal cancer, but appendiceal adenocarcinoma appears biologically and clinically distinct.

GastroAGI Takeaway

“Treat it like colon cancer” may be too simplistic. Histology, stage and molecular features may provide better relapse stratification, while routine adjuvant chemotherapy—particularly in stage II disease—deserves reconsideration. Prospective validation is needed before changing practice.