Role of Intraparotid and Neck Lymph Node Metastasis in Primary Parotid Cancer Surgery: A Population-Based Analysis

Machine learning-based survival prediction nomogram for postoperative parotid mucoepidermoid carcinoma

Parotid mucoepidermoid carcinoma (P-MEC) is a significant histopathological subtype of salivary gland cancer with inherent heterogeneity and complexity. Existing clinical models inadequately offer personalized treatment options for patients. In response, we assessed the efficacy of four machine learning algorithms vis-à-vis traditional analysis in forecasting the overall survival (OS) of P-MEC patients. Using the SEER database, we analyzed data from 882 postoperative P-MEC patients (stages I-IVA). Single-factor Cox regression and four machine learning techniques (random forest, LASSO, XGBoost, best subset regression) were employed for variable selection. The optimal model was derived via stepwise backward regression, Akaike Information Criterion (AIC), and Area Under the Curve (AUC). Bootstrap resampling facilitated internal validation, while prediction accuracy was gauged through C-index, time-dependent ROC curve, and calibration curve. The model's clinical relevance was ascertained using decision curve analysis (DCA). The study found 3-, 5-, and 10-year OS rates of 0.887, 0.841, and 0.753, respectively. XGBoost, BSR, and LASSO stood out in predictive efficacy, identifying seven key prognostic factors including age, pathological grade, T stage, N stage, radiation therapy, chemotherapy, and marital status. A subsequent nomogram revealed a C-index of 0.8499 (3-year), 0.8557 (5-year), and 0.8375 (10-year) and AUC values of 0.8670, 0.8879, and 0.8767, respectively. The model also highlighted the clinical significance of postoperative radiotherapy across varying risk levels. Our prognostic model, grounded in machine learning, surpasses traditional models in prediction and offer superior visualization of variable importance.

Topography and probability diagram of cervical and intra-parotid lymph node metastasis in parotid gland cancer

In parotid gland cancer (PGC), cervical lymph node metastasis (LNM) and intra-parotid LNM are known as significant indicators of poor prognosis. However, the topography of LNM in the affected parotid gland and the lymphatic progression of PGC has never been explored in detail. This was a retrospective analysis of data from 423 patients with previously untreated primary PGC (2005 to 2020), excluding patients with squamous cell carcinoma, lymphoma or metastatic disease in the parotid gland. The pattern of LNM was analyzed by neck sub-level and parotid sub-site. Using the conditional probability of neck level involvement, a probability diagram was plotted on several thresholds to visualize the sequential progression of LNM in PGC. The pattern of LNM progression was found to be similar between low- and high-grade pathology, but the incidence differed significantly (8.0% vs. 45.4%). Intra-parotid LNs and level IIa LNs were the most common sites (57.3% and 61.0%) of LNM in PGC, followed by level III (31.7%), Ib (25.6%), IV (22.0%), IIb (20.7%) and Va (20.7%) LNM. In intra-parotid LNs, the incidence of LNM in the deep parotid LNs was relatively low (9.4%); most intra-parotid LNMs were observed in the superficial parotid (90.6%) and peri-tumoral (in contact with the tumor) (31.3%) LNs. LNM to levels Ia, Vb and contra-lateral LNM occurred only in the very late stage. Our results provide detailed information about LNM progression in PGC at the sub-level and can help clinicians decide the treatment extent, including surgery or radiation.

Intraparotid node metastasis affects the long-term survival of patients with resectable recurrent parotid gland carcinoma

PURPOSE

The recurrence rate of parotid gland cancer is high, but research on the prognosis of recurrent parotid gland cancer (RPC) is relatively limited. We aim to determine the potential prognosis factors of RPC.

STUDY DESIGN

Retrospective cohort analysis.

SETTING

Tertiary cancer center.

METHODS

We conducted a retrospective review from 2012 to 2021 on RPC patients treated at the China National Cancer Center (CNCC). To analyze the impact of various variables on overall survival (OS) after recurrence, a univariate and multivariate Cox proportional hazard model was employed.

RESULTS

A total of 50/218 (23.0%) patients diagnosed with RPC and underwent surgery. The 5-year OS of all RPC patients in this cohort was 61.9%. 5 of 50 patients (10%) exhibited intraparotid node (IPN) metastasis. By univariate and multivariate analyses, we found that IPN metastasis was one of the prognostic factors of OS (p = 0.039) in RPC patients. The presence of IPN metastasis was also related to poor survival in individuals with negative cervical lymph nodes (CN0) (p = 0.011). In terms of the influence of surgical margins on prognosis, our findings revealed that RPC patients with negative margins exhibited a higher survival result than those with positive margins (p = 0.002).

CONCLUSION

According to this study, IPN metastasis indicate a high incidence of mortality in recurrent parotid cancer patients. Particularly, in CN0 patients, the presence of IPN metastasis was associated with poor survival in CN0 patients.

Number of positive lymph nodes is superior to neck stage of the 8th AJCC in predicting prognosis in parotid mucoepidermoid carcinoma

BACKGROUND

To clarify the impact of the number of positive lymph nodes (LNs) on the prognosis of parotid mucoepidermoid carcinoma (MEC).

METHODS

Patients who underwent neck dissection for parotid MEC were retrospectively enrolled. The primary outcome variable was overall survival (OS). Associations between OS and LN factors, including the AJCC N stage, intraparotid LN metastasis, number of positive LNs, LN size, and extranodal extension (ENE), were evaluated using Cox proportional hazard regression analyses.

RESULTS

A total of 720 patients were included with a mean age of 56 ± 16 years. There was no additional survival compromise until two positive LNs were presented. After adjusting for the number of positive LNs, intraparotid LN metastasis, ENE, and LN size were not related to prognosis. Our proposed N stage based on the number of metastatic LNs (0/1 vs. 2-4 vs. 5+) showed a superior C-index to the AJCC N stage in OS prediction.

CONCLUSION

Quantitative LN burden was an important determinant of prognosis, and the proposed N stage provided better OS stratification than the AJCC N stage.

Current management and future challenges in salivary glands cancer

Salivary gland cancers (SGCs) are rare, accounting for less than 5% of all malignancies of the head and neck region, and are morphologically heterogeneous. The diagnosis is mainly based on histology, with the complementary aid of molecular profiling, which is helpful in recognizing some poorly differentiated, borderline, or atypical lesions. Instrumental imaging defines the diagnosis, representing a remarkable tool in the treatment plan. Ultrasound and magnetic resonance are the most common procedures used to describe the primary tumour. The treatment of SGCs is multimodal and consists of surgery, radiotherapy, and systemic therapy; each treatment plan is, however, featured on the patient and disease's characteristics. On 24 June 2022, in the meeting "Current management and future challenges in salivary gland cancers" many experts in this field discussed the state of the art of SGCs research, the future challenges and developments. After the meeting, the same pool of experts maintained close contact to keep these data further updated in the conference proceedings presented here. This review collects the insights and suggestions that emerged from the discussion during and after the meeting per se.

Number of positive lymph nodes combined with the logarithmic ratio of positive lymph nodes predicts long-term survival for patients with node-positive parotid gland carcinoma after surgery: a SEER population-based study

PURPOSE

To evaluate the prognostic value of the number of positive lymph nodes (NPLN), the ratio of positive lymph nodes (pLNR), and the logarithmic ratio of positive lymph nodes (LODDS) in patients with parotid gland carcinoma. On this basis, establishing and validating an optimal nomogram.

METHODS

A total of 895 patients with T1-4N1-3M0 parotid gland carcinoma were included in our study from the Surveillance, Epidemiology, and End Results (SEER) database. Patients' data were randomly assigned to the training cohort and the validation cohort by a ratio of 7:3. Univariate and multivariate COX regression analysis were used to explore the relationship between the study factors and the prognosis of parotid gland carcinoma, including overall survival (OS) and cause-specific survival (CSS). The Akaike Information Criterion (AIC) was used to evaluate model fit. Harrell's concordance index (C-index), integrated discrimination improvement (IDI), and net reclassification index (NRI) were used to evaluate the predictive ability of these models. The decision curve analysis was used to evaluate the clinical benefit of the nomograms compared with the TNM stage.

RESULTS

NPLN, pLNR, and LODDS are independent risk factors for the prognostic of PGC. According to the AIC, C index, IDI, and NRI, the models combined with NPLN and LODDS were the best. The decision curves suggested that our nomograms had good predictive abilities for the prognosis of parotid gland carcinoma.

CONCLUSION

The two nomograms which contained NPLN and LODDS had the potential to predict OS and CSS in patients with parotid gland carcinoma.

Role of Intra-Parotid Lymph Node Metastasis in Primary Parotid Carcinoma

The parotid gland contains intra-glandular lymph nodes, the distribution of which is crucial for understanding the pathogenesis of intra-parotid lymph node metastases of parotid carcinoma and other head and neck carcinomas. Positive intra-parotid lymph node metastasis predicts the risk of positive cervical nodal metastasis. It is important to establish whether prophylactic neck dissection, including intra-parotid lymph nodes, contributes to treatment outcomes. The presence or absence of intra-parotid lymph nodes or metastasis-positive lymph nodes warrants further study. A preoperative diagnosis by imaging and fine-needle aspiration cytology of intra-parotid lymph nodes is difficult. Although intraoperative frozen section biopsy is performed during surgery, it is challenging to identify intra-parotid lymph nodes. The number of lymph nodes was the largest (47%) in the lower half of the superficial lobe, with 35% of nodes being concentrated in the inferior part of the cervicofacial branch, i.e., the lower pole of the parotid gland. Therefore, superficial parotidectomy and lower pole lobectomy need to be performed in cases in which a malignant tumor localizes to the superficial lobe or a lower pole. When intra-parotid lymph node metastases are detected during surgery, selective neck dissection (at least levels II and III) needs to be simultaneously performed.