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

Abstract

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. 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. 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). 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.