Prognostic significance of lymph node count in surgically treated patients with T 2-4 stage nonmetastatic adrenocortical carcinoma.

PURPOSE: The role of lymphadenectomy and the optimal lymph node count (LNC) cut-off in nonmetastatic adrenocortical carcinoma (nmACC) are unclear.

METHODS: Within the Surveillance, Epidemiology, and End Results (SEER) database, surgically treated nmACC patients with T2-4 stages were identified between 2004 and 2020. We tested for cancer-specific mortality (CSM) differences according to pathological N-stage (pN0 vs. pN1) and two previously recommended LNC cut-offs (≥4 vs. ≥5) were tested in pN0 and subsequently in pN1 subgroups in Kaplan-Meier plots and multivariable Cox regression models.

RESULTS: Of 710 surgically treated nmACC patients, 185 (26%) underwent lymphadenectomy and were assessable for further analyses based on available LNC data. Of 185 assessable patients, 152 (82%) were pN0 and 33 (18%) were pN1. In Kaplan-Meier analyses, CSM-free survival was 74 vs. 14 months (Δ 60 months, P ≤ 0.001) in pN0 vs. pN1 patients, respectively. In multivariable analyses, pN1 was an independent predictor of higher CSM (HR:3.13, P < 0.001). In sensitivity analyses addressing pN0, LNC cut-off of ≥4 was associated with lower CSM (multivariable hazard ratio [HR]: 0.52; P = 0.002). In sensitivity analyses addressing pN0, no difference was recorded when a LNC cut-off of ≥5 was used (HR:0.60, P = 0.09). In pN1 patients, neither of the cut-offs (≥4 and ≥5) resulted in a statistically significant stratification of CSM rate, and neither reached independent predictor status (all P > 0.05).

CONCLUSIONS: Lymphadenectomy provides a prognostic benefit in nmACC patients and identifies pN1 patients with dismal prognosis. Conversely, in pN0 patients, a LNC cut-off ≥4 identifies those with particularly favorable prognosis.