2018-19 Section 7-Neoplastic and Inflammatory Diseases of the Head and Neck eBook

Lymph Node Staging for Salivary Cancer/Aro et al

Proposed Composite Stage Grouping Pathologic AJCC T classification and our proposed LN classification both were found to be strongly and indepen- dently associated with mortality in the current study (see Supporting Table 2). Therefore, we designed a novel pro- posed composite stage grouping, analogous to the AJCC prognostic stage groups, by grouping patients based on the sum of their AJCC T classification and proposed LN classification (stage I: T1N0; stage II: T2N0/T1N1; stage IIIA: T3N0/T2N1/T1N2; stage IIIB: T3N1/T4N0/ T2N2/T1N3; stage IIIC: T4N1/T3N2/T2N3; stage IVA: T4N2/T3N3; and stage IVB: T4N3). This pro- duced 7 relatively similarly sized stage groups with clearly distinct survival curves and incrementally increased mor- tality (Fig. 4). The 5-year OS rate was 92.1%, 85.1%, 68.4%, 56.5%, 37.3%, 25.6%, and 5.3%, respectively, for proposed stages I through IVB. DISCUSSION In the current study, we demonstrated that the absolute number of positive cervical LNs is a critical predictor of SGC mortality. Each additional metastatic LN increased the risk of death without plateau. The impact was greatest up to 4 positive LNs, with each positive LN conferring an added 34% increased risk of death, whereas each positive Figure 4. Kaplan-Meier estimates for the proposed composite stage grouping based on the sum of the American Joint Com- mittee on Cancer (AJCC) eighth edition pathologic tumor clas- sification and the proposed lymph node classification. Patients with equal sums of these 2 classifications were grouped together (stage I: T1N0; stage II: T2N0/T1N1; stage IIIA: T3N0/ T2N1/T1N2; stage IIIB: T3N1/T4N0/T2N2/T1N3; stage IIIC: T4N1/ T3N2/T2N3; stage IVA: T4N2/T3N3; and stage IVB: T4N3).

Figure 3. Kaplan-Meier estimates for the (A) proposed and (B) American Joint Committee on Cancer (AJCC) eighth edi- tion lymph node (LN) classification systems in patients with salivary gland cancers.

for less lymphotropic histologies such as adenoid cystic carcinoma and acinic cell carcinoma, an increasing number of positive LNs generally was associated with a continuously increasing risk of death for all histologic subtypes. We found that our proposed LN staging sys- tem produced excellent separation of survival curves across histologies (see Supporting Fig. 4), although there were relatively few patients with acinic cell carci- noma or adenoid cystic carcinoma classified as N3 in our system.

Cancer

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