Systemic Chemotherapy for Inoperable Goblet Cell Adenocarcinomas (GCAs) and the Role of Anti-EGFR Antibodies

Introduction: Appendiceal GCAs (previously Goblet Cell Carcinoids) have variable behaviour. Systemic chemotherapy (Chemo) is often extrapolated from colon cancer. KRAS mutations (KRAS-mut) are rare and more often present in Tang-C/high grade. The role of anti-EGFR antibodies (MoAb) is unknown. Aim(s): To describe the use of Chemo and MoAb in GCAs. Materials and methods: Data from all consecutive patients (pts) with inoperable GCA (19992019) were retrospectively collected. Kaplan-Meier, log-rank test and univariate (UV)/multivariable Cox regression analyses (MVA) were performed (survival analysis). Results: Thirty-seven pts were eligible; median follow up 22 months (ms); median age 53 yrs (range 26-70); most were Tang-B/C (83.8%) and were stage (Stg) IV at diagnosis (26; 70.3%); the majority received first-line oxaliplatin-based Chemo (69.7%). Overall response rate was 24% (95%CI 12%43%); disease control rate was 80% (95%CI 60%-91%); median progression free survival (PFS) and overall survival (OS) were 5.8 ms (95%CI 4.4-7.1) and 22 ms (95%CI 14.3-29.8), respectively. There were no differences in PFS (p=0.76) or OS (p=0.70) between oxaliplatin-based vs other Chemo. Stg was significant in UV (log-rank test) for PFS (p=0.014) and OS (p=0.033) but was not significant on MVA. Fifteen pts were tested for KRAS-mut; 4 pts (26.7%) were KRAS-mut (Tang-B 1, Tang-C 3); 4 pts (Tang-B 1, Tang-C 3) with KRASwild type received MoAb (26.7%). Median PFS was 10.1 (95%CI 4.3-15.8), 6.2 (95%CI 3.0-9.5) and 3.7 ms (95%CI 0.8-6.7) for pts with KRAS-wild type (without MoA; n=7), KRAS-mut (n=4) and KRAS-wild type (with MoAb; n=4), respectively (p=0.001). Conclusion: Pts with GCA derive benefit from Chemo. The lack of benefit from MoAb suggested in our series warrants further research.