The prognosis effect of neck dissection and occult metastasis of cervical lymph nodes on CN0 parotid carcinoma and Clinical management

Abstract 0bjective To explore the prognosis effect of neck dissection and occult lymph node metastasis (OLNM) on clinically negative lymph node (CN0) parotid carcinoma (PC) and analyze risky factors of OLNM. Methods Retrospective analysis was performed on CN0 PC patients who underwent initial surgery at the National Cancer Center of China from 2012 to 2022. Propensity score matching(PSM) and Kaplan-Meier (KM) curve were used to compare the difference in progression-free survival(PFS) and overall survival (OS) between no neck dissection cohort and neck dissection cohort, and between no neck lymph node metastasis cohort and neck lymph node metastasis cohort. The clinical factors related to OLNM in the neck dissection group were analyzed by univariate and multivariate logistic regression. Results A total of 133/472 patients were CNO PC after initial surgery, including 75（56.4%） patients undergoing neck dissection, 20（26.7%） of whom were pathologically confirmed to have lymph node metastasis.There were no significant differences between no neck dissection cohort and neck dissection cohort and between no lymph node metastasis cohort and lymph node metastasis cohort on OS after PSM(P>0.05).There was no significant differences between no lymph node matastasis cohort and lymph node metastasis cohort on PFS after PSM(P=0.37).However ,neck dissection cohort had a better PFS than no neck dissection cohort after PSM(P=0.025).Poor differentiation was independent risky factor to OLNM for CNO PC (P=0.028). Conclusion For CNO PC, preventive neck dissection may prolong PFS, although it does not improve OS. Patients with lower differentiation trend to develop occult metastasis, and neck dissection should be performed as appropriate.