Lymph node ratio (LNR) and lymph node yield (LNY) in head and neck cancer: A systematic review and meta-analysis

INTRODUCTION

A growing amount of evidence points at lymph node yield (LNY) and lymph node ratio (LNR) as useful indicators in the prognostic evaluation of patients affected by head and neck squamous cell carcinoma (HNSCC) who require neck dissection. The aim of this study was to assess the importance of LNY and LNR in the prognostic evaluation of head and neck cancer patients.

MATERIALS AND METHODS

Included studies were those examining LNY and/or LNR in head and neck cancer patients. We excluded case reports or case series, thyroid cancer or salivary gland cancer studies, a sample size less than 20, and studies with incomplete or missing survival estimate. Of the 2435 studies identified through a database search, 95 were reviewed for full text and 63 were finally included for the final analysis. Electronic databases, including PubMed (MEDLINE), Embase, and Scopus were screened up to January 1, 2024. The systematic review was conducted according to the MOOSE checklist. A set of sub-group meta-analyses were performed for oral cavity, oropharynx, hypopharynx, larynx, and mixed subsites using a random-effects model. Overall survival (OS), Disease Specific Survival (DSS), and Disease-Free Survival (DFS) Hazard Ratios (HR) related to a prespecified LNR and LNY exact value were chosen as summary statistics. Cumulative Hazard Ratios with 95% Confidence Interval (CI) were presented, calculated through the inverse variance method. Heterogeneity was evaluated with I2 statistics.

RESULTS

Results of the meta-analysis showed increased OS for a higher LNY (HR 1.33 95% CI 1.23-1.45). Regarding the LNR, a lower LNR value has an impact on survival, with an OS HR of 1.96 (95% CI 1.72-2.24). The same was true for DFS (HR 2.43 95% CI 1.82-3.23), and DSS (HR 2.07 95% CI 1.83-2.33).

CONCLUSIONS

Our analysis confirms the importance of LNY and LNR as prognostic indicators. Future studies are needed to establish the optimal cut-off values for both factors. LNY and LNR have the potential to be routinely evaluated in patients who undergo neck dissection for HNSCC.

Defining a minimum nodal yield for neck dissection in mucosal head and neck squamous cell carcinoma, a systematic review

BACKGROUND

Analysis of existing literature on lymph node yield (LNY) in neck dissection (ND) for head and neck squamous cell carcinomas (HNSCC) used as a prognostic factor and an indication of treatment adequacy.

METHODS

PubMed, EMBASE and Web of Science databases were systematically searched from January 2010 to June 2023. Inclusion criteria encompassed studies on mucosal HNSCC patients undergoing ND with data on LNY and its association with survival outcomes. The quality assessment followed the REMARK guidelines.

RESULTS

Among 29 included studies, minimum LNY tresholds associated with improved survival outcomes ranged from 10 to 36.5 nodes. The heterogeneity in subsite involvement and cN0/cN + status constituted a challenge in establishing a consensus cutoff. The review highlights the need for standardized surgical techniques and pathological assessments to ensure data comparability.

CONCLUSIONS

LNY is a prognostic indicator and could reflect ND quality in HNSCC.

Histopathological Prognostic Factors of Surgically Treated HPV-Associated Oropharyngeal Squamous Cell Carcinoma: A Systematic Review and Meta-analysis

BACKGROUND

Human papilloma virus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) is rising in prevalence and is associated with better survival than HPV-negative OPSCC. In surgically treated HPV-negative OPSCCs, adverse pathologic features such as positive surgical margins, extra-nodal extension (ENE) and perineural invasion are well described to portend worse clinical outcomes. These adverse pathological features, however, are not validated prognostic markers among surgically treated HPV-positive OPSCCs. To that end, we pooled all available evidence to address the prognostic significance of these histologic features.

PATIENTS AND METHODS

This meta-analysis was performed according to PRISMA guidelines. PubMed, Web of Science and Embase databases were systematically searched for articles evaluating 13 known adverse histopathological prognostic factors of surgically treated HPV-associated OPSCC. Data analysis was done using R v4.0.5.

RESULTS

A total of 32 studies (n = 31,535) fulfilled the inclusion criteria. ENE and advanced pT stage were associated with poorer overall survival (OS) [hazard ratio (HR):1.80, 95% confidence interval (CI) [1.59-2.03], p < 0.0001, HR: 3.28, 95% CI [2.20-4.87], p = 0.0025]; disease-specific survival (DSS) (HR: 3.14, 95% CI [1.20-8.26], p = 0.0327, HR: 3.49, 95% CI [2.45-4.96], p = 0.0043) and disease-free survival (DFS) (HR: 2.03, 95% CI [1.05-3.94], p = 0.0397, HR: 3.66, 95% CI [2.81-4.77], p = 0.0001) respectively. The presence of lymphovascular invasion (HR: 1.46, 95% CI [1.22-1.75], p = 0.0018) and positive margins (HR: 1.50, 95% CI [1.185-1.899], p = 0.0069) significantly worsen OS.

CONCLUSION

ENE, advanced pT stage, positive margins and lymphovascular invasion were adverse histologic prognostic marker among surgically treated HPV-positive OPSCC. The presence of these factors should be carefully evaluated in order to select the optimal patients for surgical treatment.

Factors influencing lymph node yield in head and neck squamous cell carcinoma: A scoping review

OBJECTIVES

In head and neck cancer surgery, several studies have demonstrated the prognostic significance of lymph node yield (LNY). To our knowledge, no review has evaluated both the contributing factors to LNY and its impact on survival outcomes across all head and neck squamous cell carcinoma (HNSCC) subsites.

MATERIALS AND METHODS

A scoping review of LNY in HNSCC was conducted according to The Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) framework to answer the following research questions: 1) Which surgeon, pathologist, and patient characteristics influence LNY? 2) Which anatomic subsites does LNY impact survival?

RESULTS

Surgeon experience and variation in pathology protocols and personnel can impact LNY. Extent of nodal dissection, advanced tumor characteristics, and treatment at an academic facility are associated with increased LNY. Patient characteristics such as age <40, male gender, and BMI > 30 are associated with increased LNY. In the oral cavity, LNY > 18 is an independent predictor of improved overall survival (OS), disease free survival (DFS), and disease-specific survival (DSS). In the oropharynx, published studies show mixed results with regards to the impact of LNY on OS, DFS, and DSS. LNY has not been associated with OS or DFS in the larynx, irrespective of nodal threshold.

CONCLUSIONS

Provider and patient characteristics may impact LNY. LNY ≥ 18 is associated with a survival benefit in the oral cavity and HNSCC overall. Further investigation of LNY particularly in prospective clinical trials is required prior to its adoption as a quality metric in HNSCC.

Lymph node level ratio: Are we relying too much on numbers?

The lymph node level ratio appears to be a continuation of nodal yield and nodal density, two prognostic metrics already in use. A retrospective analysis conducted in the current study showed that a value of fewer than 4 lymph nodes/level is linked to a lower overall and disease-specific survival. This letter aims to review the reasoning behind the use of node level ratios and nodal yields as quality and prognostic indicators, and to explore possible factors that could affect these.

Factors influencing nodal yield in neck dissections for head and neck malignancies

OBJECTIVE

A standard lateral neck dissection should yield at least 18 lymph nodes. The goal of the present study was to examine what factors might influence the number of lymph nodes retrieved during a neck dissection.

METHODS

This was a retrospective cohort study in a tertiary academic referral centre for head and neck oncology. Two hundred and nineteen consecutive neck dissections were examined. Age of the patient and primary site were recorded, along with tumour histology, previous radiotherapy and final nodal count.

RESULTS

The mean age was 62.2 ± 13.0 years. The most common primary site was the oral cavity (38.8 per cent). The mean number of lymph nodes was 30.63 ± 13.9. In total, 17.8 per cent had undergone previous radiotherapy. The mean number of lymph nodes was 33.26 ± 13.27 in patients with no previous radiation exposure and 18.47 ± 9.46 in those with previous radiation treatment.

CONCLUSION

Lymph node yield from a neck dissection is likely multi-factorial in nature. Previous radiotherapy, the only significant contributor, led to a mean reduction of lymph node yield from 33.3 to 18.5.

Low postoperative lymphocyte count increases risk of progression in human papillomavirus associated oropharyngeal cancer

BACKGROUND

We aim to explore the prognostic role of absolute lymphocyte count (ALC) before, during, and after treatment on oncologic outcomes in human papillomavirus associated oropharyngeal cancer (HPV(+)OPSCC).

METHODS

Retrospective cohort at a tertiary center, 2006-2018. Multivariable Cox regressions were used to determine the effect of ALC on risk of progression. Univariate linear regression was performed to determine clinical factors associated with lower ALC.

RESULTS

All 197 patients underwent primary surgery. Mean (SD) ALC nadirs (×10⁹  cells/L) were: baseline (N = 149): 1.69 (0.56); postoperative (N = 126): 1.58 (0.59); post-RT (N = 141): 0.68 (0.35) and long-term (N = 105): 0.88 (0.37). Lower baseline ALC nadir was associated with worse overall survival (HR 3.85, 95%CI: 1.03-14.29, p = 0.04). Lower postoperative ALC nadir was associated with higher risk of progression (HR 2.63, 95%CI: 1.04-6.67, p = 0.04).

CONCLUSIONS

Lower baseline ALC is associated with worse survival, whereas lower postoperative ALC is associated with increased risk of progression in surgically treated HPV(+)OPSCC.

LEVEL OF EVIDENCE: 3

Treatment Options in Early Stage (Stage I and II) of Oropharyngeal Cancer: A Narrative Review

OBJECTIVE

to show an overview on the treatments' options for stage I and II oropharyngeal carcinomasquamous cell carcinoma (OPSCC).

BACKGROUND

The traditional primary treatment modality of OPSCC at early stages is intensity modulated radiation therapy (IMRT). Trans-oral robotic surgery (TORS) has offered as an alternative, less invasive surgical option. Patients with human papilloma virus (HPV)-positive OPSCC have distinct staging with better overall survival in comparison with HPV-negative OPSCC patients.

METHODS

a comprehensive review of the English language literature was performed using PubMed, EMBASE, the Cochrane Library, and CENTRAL electronic databases.

CONCLUSIONS

Many trials started examining the role of TORS in de-escalating treatment to optimize functional consequences while maintaining oncologic outcome. The head-neck surgeon has to know the current role of TORS in HPV-positive and negative OPSCC and the ongoing trials that will influence its future implementation. The feasibility of this treatment, the outcomes ensured, and the side effects are key factors to consider for each patient. The variables reported in this narrative review are pieces of a bigger puzzle called tailored, evidence-based driven medicine. Future evidence will help in the construction of robust and adaptive algorithms in order to ensure the adequate treatment for the OPSCC at early stages.

Prognostic value of lymph node ratio versus American Joint Committee on Cancer N classification for surgically resected human papillomavirus-associated oropharyngeal squamous cell carcinoma

BACKGROUND

We compared prognostic values of lymph node ratio (LNR) and AJCC 8 N classification in surgically resected human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC).

METHODS

Using the National Cancer Database, we identified patients with HPV-associated OPSCC from 2010 to 2016 who underwent definitive surgical resection. Patients were analyzed by nodal grouping (LNR, N stage) and adjuvant radiation therapy(RT). Primary endpoint was overall survival.

RESULTS

We identified 4166 patients. Survival analysis showed significant improvement for LNR≤6% versus >6% (5 year OS% 92.7% vs. 83.7%, p < 0.001). N classification demonstrated good prognostic ability (5 year OS% for pN0, pN1, pN2 were 91.3%, 90.1%, 78.8%, p < 0.001), but poor separation among stages (compared to pN0: pN1 HR 1.40 [95% CI 0.63, 3.09], p = 0.41; pN2 HR 2.50 [95% CI 1.08, 5.81], p = 0.033). RT improved survival in the LNR > 6% group (5 year OS% 85.4% vs. 74.9%, p < 0.001; HR 0.41 [95% CI 0.28, 0.58], p < 0.001).

CONCLUSIONS

LNR should be considered an adjunct category in future staging systems for HPV-associated OPSCC.

Patterns of Nodal Metastases and Predictors of Occult Disease in HPV-Associated Oropharynx Cancer

OBJECTIVE

For human papilloma virus-associated oropharynx squamous cell carcinoma (HPV+ OPSCC), we evaluated the distribution of neck-level lymph node (LN) metastasis, based on postsurgical histopathology, and the incidence of and risk factors for occult LN metastases, as these patterns need clarification for this newer cancer subset.

STUDY DESIGN

Retrospective cohort study.

SETTING

National Cancer Database (NCDB).

METHODS

We analyzed 2358 patients in the NCDB with HPV+ OPSCC who underwent neck dissection (ND) from 2010 to 2015. Incidence and distribution of LN metastases were calculated for neck levels I to V. Variables associated with occult LN metastasis were assessed by multivariate logistic regression.

RESULTS

In therapeutic NDs (n = 1935), the following proportions of positive LNs were found: level I, 9.0% (n = 175); level II, 81.0% (n = 1568); level III, 29.6% (n = 573); level IV, 11.9% (n = 230); and level V, 4.9% (n = 95). In elective NDs (n = 423), occult-positive LNs were found in 35.8% (n = 152), with the following proportions by level: level I, 3.3% (n = 14); level II, 26.9% (n = 114); level III, 8.7% (n = 37); level IV, 4.0% (n = 17); and level V, 0.2% (n = 1). The presence of occult LNs was independently associated with a Charlson-Deyo score of 1 (odds ratio, 2.26; 95% CI, 1.18-4.31; P = .014) and lymphovascular invasion (odds ratio, 5.91; 95% CI, 3.21-11.18; P < .001). Occult LN metastases were not significantly associated with pT classification, primary site, or number of LNs resected.

CONCLUSION

For HPV+ OPSCC, occult nodal disease is common. Therapeutic NDs should encompass at least levels II, III, and IV and possibly I, whereas elective NDs could possibly encompass levels II and III.

LEVEL OF EVIDENCE

4.

Impact of Lymph Node Yield on Survival in Surgically Treated Oropharyngeal Squamous Cell Carcinoma

Objectives

(1) To estimate the association between neck dissection lymph node yield (LNY) and survival among patients with surgically treated human papilloma virus (HPV)–associated oropharyngeal squamous cell carcinoma (OPSCC). (2) To identify a clinically relevant quality metric for surgical treatment of HPV-related OPSCC.

Study Design

Retrospective cohort study.

Setting

National Cancer Database.

Subjects and Methods

From the National Cancer Database, 4130 patients were identified with HPV-associated OPSCC treated with primary surgery from 2010 to 2016. Based on prior literature, an adequate neck dissection LNY was defined as ≥18 lymph nodes. To determine whether LNY is associated with survival, univariable and multivariable Cox proportional hazards regression was performed. Analysis was stratified by adjuvant therapy regimen.

Results

A total of 2113 patients (51.2%) underwent surgery with or without adjuvant radiation (S ± RT), and 2017 patients (48.8%) underwent surgery with adjuvant chemoradiation. LNY ≥18 was associated with a 5-year survival benefit of 7.15% (91.7% for LNY ≥18, 84.5% for LNY <18, P = .004) for the S ± RT cohort on unadjusted survival analysis. For the S ± RT group, LNY ≥18 was associated with decreased hazard of death (hazard ratio, 0.45; 95% CI, 0.29-0.70; P < .001) after adjustment for patient characteristics, TNM staging, surgical margins, extranodal extension, and treating facility characteristics. For surgery with adjuvant chemoradiation, the adjusted hazard ratio estimate for LNY ≥18 was 0.64 (95% CI, 0.41-1.00), but the result was not statistically significant ( P = .052).

Conclusion

An adequate LNY from a neck dissection may affect survival when HPV-related OPSCC is treated with up-front surgery.

Lymph node yield and lymph node ratio in oral cavity and oropharyngeal carcinoma: Preliminary results from a prospective, multicenter, international cohort

OBJECTIVES

Recently, Lymph Node Yield (LNY) and Lymph Node Ratio (LNR) have emerged as prognostic indicators in head and neck cancer. However, there is a lack of data regarding the LNY and LNR values in the specific neck levels dissected and regarding the factors that influence these values.

MATERIALS AND METHODS

Preliminary results of the NCT03534778 trial are reported. LNY and LNR values were estimated for 100 patients with oral or oropharynx carcinoma, from November 1, 2018 to September 30, 2019.

RESULTS

Overall, the mean number of lymph nodes retrieved was 34.4 (95% confidence interval [CI] 31.6-37.3). LNY means and CI per single neck level were as follows: level I 5.5 lymph nodes harvested (95% CI 3.5-7.5), level II 15.4 (95% CI 10.6-20.2), level III 8.0 (95% CI 4.6-11.3), level IV 6.3 (95% CI 3.4-9.15), level V 6.3 (95% CI 3.6-9.0). cN+ patients had a higher number of lymph nodes retrieved, odds ratio (OR) 1.2 (95% CI 1.05-1.36). Smokers had less lymph nodes harvested, OR 0.78 (95% CI, 0.71-0.87). Mean LNR was 0.063 (95% CI 0.047-0.078). A multiple regression analysis showed that anatomic site, pN, smoking status and LNY statistically significantly predicted the LNR (p < 0.05) CONCLUSIONS: The LNY and LNR values are influenced by various demographic and pathological characteristics of the patient, such as the number of dissected levels, primary site, cN positivity, and smoking status.

Lymph Node Ratio in HPV-Associated Oropharyngeal Cancer: Identification of a Prognostic Threshold

OBJECTIVE

To evaluate the utility of lymph node ratio (LNR) as a prognostic factor for survival and recurrence in surgically treated patients with human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC).

STUDY DESIGN

Retrospective cohort study.

METHODS

In this retrospective cohort study of a tertiary healthcare system in a major metropolitan area, we reviewed 169 consecutive patients with HPV-related OPSCC treated using transoral robotic surgery. Univariable and multivariable Cox proportional hazards regression analysis with stratified models were used to compare LNR with other traditional clinicopathologic risk factors forrecurrence and survival. An LNR cutoff was found using the minimal P approach.

RESULTS

Multivariable Cox regression models showed that each additional percentage increase in LNR corresponded to an adjusted hazard ratio (HR) of 1.04 (confidence interval [CI] 1.02-1.07). LNR was more significant when adjusted for adequate lymph node yield of ≥ 18 nodes (HR 5.05, 95% confidence interval [CI] 1.38-18.47). The minimal P generated cutoff point at LNR ≥ 17% demonstrated a HR 4.34 (95% CI 1.24-15.2) for disease-free survival.

CONCLUSION

For HPV-related OPSCC, continuous LNR and an LNR threshold of 17% could be helpful in identifying recurrent disease in addition to measures such as lymph node number alone.

LEVEL OF EVIDENCE

4.