Intraparotid lymph node metastasis affects distant metastasis in parotid adenoid cystic carcinoma

Abstract

To evaluate the relationship between factors of metastatic intraparotid lymph node (IPLN) and distant metastasis in parotid adenoid cystic carcinoma (ACC). Patients with surgically treated parotid ACC were retrospectively enrolled, and primary outcome variable was distant metastasis free survival (DMFS). The effect of factors of metastatic IPLN on DMFS was evaluated using Cox model. In total, 232 patients were included. Extranodal extension of IPLN and cervical lymph nodes did not impact the DMFS, and the 7th but not 8th AJCC N stage was associated with DMFS. Groups of 0 and 1 metastatic IPLN had comparable DMFS, but presence of 2+ positive IPLN was related to increased worse DMFS (p = 0.034, HR 2.09). A new N stage (0 vs 1–2 vs 3+) based on total positive lymph node number exhibited better C-index than traditional N stage. IPLN metastasis increased the risk of distant metastasis, and the impact was mainly determined by the number of metastatic IPLN. Our proposed N stage provided better DMFS prediction than the 8th AJCC N classification.

The 8th AJCC classification is inferior to a new neck stage based on intraparotid lymph node in parotid gland cancer

“…However, the authors failed to find an association between ENE and distant metastasis, the risk of which was significantly increased in solid cancers by ENE. Our previous study assessed the predictors of DMFS in 232 patients with adenoid cystic carcinoma and reported that ENE in neither the cervical nor the intraparotid LN affected DMFS [ 7 ]. The current study is a further supplement, confirming that ENE did not compromise survival, irrespective of LN location.…”

“…However, the presence of two or more positive LNs predicted significantly decreased disease control and increased death risk. Our previous study showed that intraparotid LN metastasis was significantly associated with inferior prognosis; however, the impact was not apparent until there were at least two metastatic intraparotid LNs in parotid adenoid cystic carcinoma [ 7 ]. These three studies combined with ours suggest that the impact of the intraparotid LN metastasis burden should be emphasized in the evaluation of LN status.…”

“…However, among these researches, the impact of ENE has shown conflicting results. Few studies have described that ENE poses little effect on survival in PGC [ 4 , 5 , 7 , 9 ]; however, Lee et al [ 8 ] reported that patients with ENE have an increased possibility of recurrence and death. Contrarily, the embryologic development of the parotid gland raises the possibility of intraparotid LNs, which can also be involved with metastasis.…”