Cancer-specific survival in non-mucinous appendiceal adenocarcinomas after local resection versus right hemicolectomy: A Surveillance, Epidemiology, and End Results database study

Abstract

Background: Adenocarcinomas of the appendix are rare cancers for which no National Comprehensive Cancer Network guidelines exist, and for patients who undergo resection with curative intent, there is a paucity of data on prognostic factors affecting long-term cancer-specific survival. We aimed to compare the cancer-specific survival outcomes in adult patients with appendiceal non-mucinous adenocarcinoma undergoing either local resection versus right hemicolectomy.

Methods: This was a retrospective study from the National Cancer Institute Surveillance, Epidemiology, and End Results of patients who underwent curative resection over a 15-year period (2004-2019) for primary appendiceal adenocarcinoma. Out of 16,699 patients, 14,945 were excluded (exclusion criteria were non-adenocarcinoma histological types and patients with regional or distant metastasis as per National Cancer Institute Surveillance, Epidemiology, and End Results stage). Effects of factors (age, race, tumor biology [mucinous versus non-mucinous tumors], the extent of resection of the primary lesion, and lymph nodes) on cancer-specific long-term survival were studied. Survival analysis was performed using the Kaplan-Meier method. Survival outcomes were reported as mean survival (months).

Results: Of 1,754 patients, 827 (47.1%) were women, and 927 (52.1%) were men. The mean age in years (± standard deviation) was 62.43 ± 14.3. The racial distribution was as follows: Black 237 (13.5%), White 1,398 (79.7%), and Other 119 (6.8%). A total of 771 (44.6%) underwent local resection (appendectomy or segmental resection of colon without lymph node resection), and 983 (55.4%) underwent hemicolectomy with lymph node resection. Favorable survival prognosticators were age <50 years, White race, and well-differentiated histology. Patients with mucinous tumors experienced better survival. Patients who underwent right hemicolectomy with lymph node resection experienced better survival compared with those who had an appendectomy or segmental colonic resection for non-mucinous tumors rather than mucinous tumors.

Conclusion: We report novel demographic, tumor-related, and operative prognostic factors impacting long-term cancer-specific survival in patients who undergo resection for appendiceal adenocarcinoma. The extent of resection of the primary lesion with draining lymph nodes determines long-term cancer-specific survival in non-mucinous appendiceal adenocarcinomas.