Lymph node yield in treatment naïve cases of head and neck squamous cell carcinoma: en bloc lymphadenectomy versus level-by-level dissection

Lymph node level ratio as a predictor of survival in oral cavity squamous cell carcinoma

OBJECTIVE

To evaluate whether nodal yields and ratios based on level serves as prognostic indicators in patients with oral cavity squamous cell carcinoma undergoing neck dissection.

MATERIALS AND METHODS

A retrospective analysis of 342 patients with oral cavity squamous cell carcinoma treated surgically between 1998 and 2017 were included.Demographics and clinicopathologic data were collated. Disease specific survival and overall survival were analyzed via Kaplan-Meier method and log-rank test as well as univariable and multivariable Cox models.

RESULTS

Total nodal yield is associated with improved overall and disease specific survival (p < 0.01). Total positive nodal yield (p < 0.01), positive nodal ratio per level (p < 0.001), and identification of <4 lymph nodes/level (p < 0.001) are associated with worse disease specific survival and overall survival. A ratio of at least 4 lymph nodes/level dissected yields the maximal hazard ratio on for both disease specific and overall survival optimizes the Kaplan-Meier split between survival groups. After controlling for sex, age, margin status, disease stage, extranodal extension, perineural invasion, and lymphovascular invasion as fixed covariates in the Cox models, a nodal level ratio of 4 lymph nodes/level provides hazard ratio (95% CI) of 3.59 (1.69, 7.60); p < 0.0006) for disease free survival and 2.90 (1.54, 5.46; p < 0.001) for overall survival.

CONCLUSION

Nodal level ratio of < 4 lymph nodes/level is associated with worse disease specific and overall survival in oral cavity squamous cell carcinoma. This level-specific metric may prove useful qualitatively and in predicting survival in oral cavity cancer with broader utility to address variations in levels of neck dissection performed.

MRI visibility and displacement of elective lymph nodes during radiotherapy in head and neck cancer patients

Background and purpose

To decrease the impact of radiotherapy to healthy tissues in the head and neck region, we propose to restrict the elective neck irradiation to elective lymph nodes at risk of containing micro metastases instead of the larger lymph node volumes. To assess whether this new concept is achievable in the clinic, we determined the number, volume changes and displacement of elective lymph nodes during the course of radiotherapy.

Materials and methods

MRI scans of 10 head and neck cancer (HNC) patients were acquired before radiotherapy and in week 2, 3, 4 and 5 during radiotherapy. The weekly delineations of elective lymph nodes inside the lymph node levels (Ib/II/III/IVa/V) were rigidly registered and analyzed regarding number and volume. The displacement of elective lymph nodes was determined by center of mass (COM) distances, vector-based analysis and the isotropic contour expansion of the lymph nodes of the pre-treatment scan or the scan of the previous week in order to geographically cover 95% of the lymph nodes in the scans of the other weeks.

Results

On average, 31 elective lymph nodes in levels Ib-V on each side of the neck were determined. This number remained constant throughout radiotherapy in most lymph node levels. The volume of the elective lymph nodes reduced significantly in all weeks, up to 50% in week 5, compared to the pre-treatment scan. The largest median COM displacements were seen in level V, for example 5.2 mm in week 5 compared to the pre-treatment scan. The displacement of elective lymph nodes was mainly in cranial direction. Geographical coverage was obtained when the lymph node volumes were expanded with 7 mm in case the pre-treatment scan was used and 6.5 mm in case the scan of the previous week was used.

Conclusion

Elective lymph nodes of HNC patients remained visible on MRI and decreased in size during radiotherapy. The displacement of elective lymph nodes differ per lymph node level and were mainly directed cranially. Weekly adaptation does not seem to improve coverage of elective lymph nodes. Based on our findings we expect elective lymph node irradiation is achievable in the clinic.

Prognostic Value of Pathologically Positive Nodal Number in p16-Negative Oropharyngeal and Hypopharyngeal Squamous Cell Carcinoma with pN3b Status

In this study, we aimed to investigate the prognostic value of the number of pathologically positive nodes (pN+) in p16-negative oropharyngeal (OPSCC) and hypopharyngeal (HPSCC) squamous cell carcinoma cases with pN3b status after surgery. We reviewed the clinical and pathological features of 120 newly diagnosed p16-negative OPSCC and HPSCC patients with pN3b status after radical surgery. The primary endpoints were the 5-year overall survival (OS), cancer-specific survival (CSS), and their prognostic factors. We used the Cox proportional hazards model for survival analysis. We generated predictive nomograms that incorporated the clinicopathological factors of OS and CSS. The 5-year OS and CSS rates were 44.1% and 59.1%, respectively. The optimal number of pN+ to predict the 5-year OS and CSS was pN+ = 3. In the Cox model, we observed that pN+ ≥ 3 was a significantly negative predictor of OS (HR: 1.9, 95% CI: 1.1–3.2, p = 0.021) and CSS (HR: 2.3; 95% CI: 1.2–4.6; p = 0.015). After adding the pN+ variable, the c-index of the predictive nomogram incorporating assorted clinicopathological factors increased from 0.66 to 0.689 for OS and from 0.713 to 0.75 for CSS. The results highlight the prognostic value of the pN+ number in p16-negative OPSCC and HPSCC patients with pN3b status.