Nodal yield and topography of nodal metastases from oral cavity squamous cell carcinoma - An audit of 1004 cases undergoing primary surgical resection

Proposals for the delineation of neck clinical target volume for definitive Radiation therapy in patients with oral/ oropharyngeal squamous cell cancer based on lymph node distribution

PURPOSE/OBJECTIVE(S)

To establish the distribution pattern of cervical lymph node metastasis (LNM) and propose optimized clinical target volume (CTV) boundaries specific to oral/ oropharyngeal squamous cell cancer (OSCC/OPSCC).

MATERIALS/METHODS

531 patients with pathologically confirmed OSCC/OPSCC were enrolled from January 2013 to June 2022. Patients were stratified into two groups based on the minimal distance from the lesion's edge to the body's midline: ≤1 cm or > 1 cm. The geometric center of cervical metastatic LN was marked on a template CT. LN distribution probability maps were established. The relationships between the LN distribution and consensus guidelines were analyzed to propose modifications for CTV boundaries specific to OSCC/OPSCC.

RESULTS

A total of 1962 positive LNs were enrolled. Compared with the > 1 cm group, the ≤ 1 cm group has following feature tendencies: male smokers, younger, median organs, large gross lesion, infiltrative growth pattern, contralateral LNM. The most frequently involved level of LNM was ipsilateral II, but ipsilateral Ib had the highest involvement rate in the > 1 cm OSCC group. In addition, tongue cancer had a higher incidence of LN extranodal extension (ENE), which mainly distributes in ipsilateral level II. The skip metastasis was prone to from level III to Vb (3.5 %) in LN(+)/ENE (-), and level Ib to VIa (3.7 %) in LN(+)/ENE (+). Accordingly, we proposed the following modifications: 1. only including lateral and posterior margin of submandibular gland within 5 mm; 2. retracting posterior boundary of level II to front edge of levator scapula muscle, and descending the upper boundary to transverse process of C2 vertebra only for OSCC; 3. including posterior third of thyroglossal muscle or anterior edge of sternocleidomastoid muscle; 4. sparing level Va in case of only level II involvement; 5. including upper area of the thyroid cartilage plate in case of level Ib LN(+)/ENE (+); 6. sparing level VIIa is considered.

CONCLUSION

This is the first description of LN topographic spread patterns for OSCC/OPSCC. Modified CTV for prophylactic irradiation was proposed to spare the organs at risk and minimize adverse effects.

Do patients with cN0 oral squamous cell carcinoma benefit from elective neck dissection? A large-scale population-based study

BACKGROUND

The neck management of clinical-nodal negative (cN0) oral squamous cell carcinoma (OSCC) remains controversial. Elective neck dissection (END) and observation are the main strategies, but it is still not clear who could benefit the most from END. The purpose of this study was to clarify the potential clinical factors that affect the therapeutic value of END and to explore the actual characteristics associated with benefit from END.

METHODS

Patients with cN0 OSCC were identified in the SEER database from 2000 to 2019. 5-year Overall survival (OS) and disease-specific survival (DSS) were analyzed using the Kaplan‒Meier method, and the hazard ratios (HRs) for survival were estimated using the Cox regression model. Multiple subgroup analyses of DSS and OS among different factors, comparing END and No END, were performed.

RESULTS

A total of 17,019 patients with cN0 OSCC were included. The basic survival analysis and Cox regression model showed that END increased the probability of 5-year DSS and OS and was an independent prognostic factor. However, among patients who underwent only primary tumor surgery, no significant differences were found between the END and No END groups in 5-year DSS (P = 0. 585) and OS (P = 0.465). Further subgroup analysis showed that primary sites and T stage, but not other factors, might influence the benefit of END. Significant differences were found for T1 (P < 0.001 for OS) and T2 (P = 0.001 for DSS and < 0.001 for OS) tongue squamous cell carcinoma (TSCC) but not for other primary tumor sites.

CONCLUSION

This large-scale retrospective population-based cohort study suggests that not all patients with cN0 OSCC could benefit from END. Patients with cN0 TSCC are recommended to undergo END, especially with early-stage tumors.

Role of sentinel lymph node biopsy for oral squamous cell carcinoma: Current evidence and future challenges

Sentinel lymph node biopsy (SLNB) has been used across oncological specialties for prognostication, staging, and identification of occult nodal metastasis. Recent studies demonstrated the potential clinical utility of SLNB in oral cavity squamous cell carcinoma (OCSCC). Elective neck dissection is the current standard of care in early management of OCSCC with depth of invasion greater than 2-4 mm; however, majority of patients ultimately do not have nodal disease on final pathology. SLNB is an alternative procedure widely adopted in early cancer management in many oncological subspecialities. Several considerations such as depth of invasion, nodal mapping, histopathology methods, operator variability, postoperative complications, and advancement in preoperative and intraoperative imaging technology can guide the appropriate application to SLNB in OCSCC. The aim of this review is to discuss the current evidence for SLNB in the treatment of early stage OCSCC, imaging technologies that support SLNB procedures, and studies that are currently underway.

Influence of Site, Size, Depth of Invasion and Histologic Grading on the Occurrence of Cervical Level IIb Metastasis and Extranodal Extension in Clinically N0 Neck of Patients with OSCC: A Single Center Retrospective Analysis

Background

Depth of Invasion ≥ 4 mm, T stage and primary site with more than 20% chances for occult metastasis are currently the accepted indications for elective neck dissection. Nodal metastasis decreases survival by 50%. ENE further reduces the prognosis. Dissection of level IIb lymph nodes in clinically N0 neck does not improve survival.

Methods

A total of 320 patients were evaluated. Binary and multiple logistic regression and chi-square test were used for data analysis. ROC curve with Youden's J index was used to set up a cutoff value for DOI. The predictor variables were site, size, grading and depth of invasion of primary tumor. Incidence of level IIb metastasis and ENE were the outcomes.

Results

The study revealed a significant association and risk stratification between primary tumor characteristics with the occurrence of ENE. The cutoff value for DOI predicting ENE was 12.5 mm. Tumors of the oral tongue were an independent risk factor for level IIb metastasis.

Discussion

Size of primary tumor, DOI, tumors of the mandibular alveolus and poor grading are independent risk factors for ENE. Isolated metastasis to level IIb rarely occurs in the absence of concomitant level IIa metastasis. Size, DOI and grading were significantly associated with level IIb metastasis. However, only tumors of the oral tongue were independent risk factor.

Primary tumour characteristics poorly correlate with extracapsular spread and cervical sublevel IIb metastasis in patients with oral squamous cell carcinoma and clinically N0 neck: A retrospective study

Introduction:

Nodal metastasis reduces the survival by 50% in head-and-neck squamous cell carcinomas. The presence of nodal extension/extracapsular spread (ECS) further reduces survival. Current literature favors a selective level IIb sparing neck dissection in clinically N0 neck. Studies have evaluated the role of primary tumour size, number of lymph nodes, and depth of invasion (DOI) with the occurrence of extranodal extension (ENE).

Patients and Methods:

Patients were retrospectively reviewed who presented with oral cavity carcinomas and clinically N0 neck. Relationship was sought between tumour site, size, histological grading, DOI, and the occurrence of level IIb metastasis and ECS. A P < 0.05 was considered statistically significant.

Results:

The relationship showed insignificant correlation with P values (0.6643, 0.6704, 0.6779, and 0.6779) between site, size, grading, DOI, and level IIb and ENE.

Discussion:

Previous studies have shown DOI >5 mm and lymph node size 15 mm and multiple lymph nodes predict ECS. DOI and primary site with more than 20% for occult metastasis predicts elective neck treatment. However, in our study, no correlation was found between primary tumour characteristics and ECS or level IIb metastasis. Elective neck dissection is the standard surgical protocol from both diagnostic and therapeutic viewpoints. The only criterion for level IIb dissection is concomitant presence of level IIa involvement intraoperatively. Since ENE can occur early in the disease process, elective neck dissection remains the standard of care.