Patterns of lymph node involvement for oral cavity squamous cell carcinoma.

Aim: Whereas the prevalence of lymph node level (LNL) involvement in oral cavity squamous cell carcinomas (OCSCC) has been reported, the details of lymphatic progression patterns are insufficiently quantified. We investigate how the risk of metastases in each LNL depends on the involvement of adjacent LNLs, T-category, subsite, primary tumor lateralization, and other risk factors.

Methods: We retrospectively analyzed patients with newly diagnosed OCSCC from two institutions, totaling 348 patients. Involvement of LNLs I-V was recorded individually based on pathology after neck dissection with clinicopathological factors. The dataset is publicly available in a previously developed web-app, which allows querying patients with specific combinations of co-involved LNLs and tumor characteristics.

Results: Ipsilateral involvement prevalence of levels I-III was higher for advanced T-category (T3/T4) patients (32 %, 38 %, 14 %) compared to early (T1/T2) patients (14 %, 23 %, 11 %). Involvement of level I increased the involvement probability in levels II and III. Similarly, involvement of level II increased the involvement probability in levels I and III. However, there was significant isolated involvement of level I or II. Advanced nodal involvement (>1 LNL involved) was more frequent for patients with extracapsular extension. Overall contralateral involvement in levels I-III was 7 %, 4 %, 3 % and more frequent for more advanced ipsilateral involvement and for midline-crossing tumors. Involvement of levels IV and V was rare: 3 % ipsilateral and 1 % contralateral in both levels.

Conclusions: Detailed quantification of LNL involvement in OCSCC depending on involvement of adjacent LNLs and clinicopathological factors may allow further personalizing guidelines on elective nodal treatment.