Background: Right hemicolectomy (RHC) for nodal staging is recommended for nonmucinous adenocarcinoma of the appendix (NMACA), but it is unclear whether a subgroup of patients at low risk for lymph node (LN) metastasis exists who may be managed with a less extensive resection.
Patients and methods: Patients with NMACA without distant metastases who underwent margin negative resection via either RHC or appendectomy/partial colectomy (A/PC) were evaluated from the National Cancer Database (2004-2016). Patients at low risk for LN metastasis were identified. Multivariable survival analysis was performed, and 5-year overall survival (OS) was estimated.
Results: Of the 2487 patients included, 652 [26.2%; 95% confidence interval (CI) 24.5-28.0%] had LN metastases. T4 T stage [odds ratio (OR) 4.2, p = 0.032], poorly/undifferentiated histology (OR 2.2, p = 0.004), and lymphovascular invasion (LVI) (OR 4.4, p < 0.001) were associated with LN positivity. One hundred and thirteen patients (4.5%) had tumors at low risk for LN metastasis (T1 T stage, well/moderately differentiated tumors without LVI), and the rate of LN metastasis for this group was 1.8% (95% CI 0.5-6.2%). Conversely, the LN metastasis rate among the 2374 non-low-risk patients was 27.4% (95% CI 25.6-29.2%). Performance of A/PC instead of RHC was associated with a survival disadvantage among all patients (hazards ratio 1.5, p = 0.049), but among the low-risk cohort, 5-year OS did not differ based on resection type (88.3% A/PC versus 92.7% RHC, p = 0.305).
Conclusions: Although relatively uncommon, early, pathologically favorable NMACA is associated with a very low risk of LN metastasis. These select patients may be managed with a less extensive resection without compromising oncologic outcomes.
© 2022. Society of Surgical Oncology.