Risk factors for conditional survival and lymph node metastases in appendiceal adenocarcinoma

AIM: Right hemicolectomy is the standard procedure for appendiceal adenocarcinoma to ensure adequate lymph node sampling. However, due to biological diversity, appendiceal adenocarcinoma has a wide survival range. Therefore, this study investigated risk factors associated with lymph node metastases and conditional overall survival, or the probability of surviving an additional 2 years after treatment, which may provide a more dynamic estimate of survival. METHOD: A retrospective cohort study was conducted using the National Cancer Database to identify adults undergoing segmental colectomy for stage I-III appendiceal adenocarcinoma from 2004 to 2018. Cox regression models estimated patient and treatment effects on risk of lymph node metastases and survival outcomes. RESULTS: Of 3185 patients, 24% had nodal metastases. Probability of lymph node involvement increased with higher tumour grade, non-mucinous and signet cell histology, and advanced T stages. Overall, 5-year survival was 79%. After 2 years, 2716 patients (85%) survived, with 86% of that cohort surviving to 5 years. Age > 70, public or no insurance, higher grade, increasing pathological T stage and nodal metastases were associated with worse 2-year conditional overall survival (all p < 0.05). CONCLUSION: In this national cohort, one-fourth of appendiceal adenocarcinoma patients had nodal metastases, which were associated with worse prognosis, validating the importance of segmental colectomy in staging and management. Although patients who survived at least 2 years had improved long-term outcomes, those with higher T stage, tumour grade or nodal involvement remained at elevated risk of mortality and may need prolonged close surveillance.