Clinically Node-Negative Parotid Gland Cancers: Prognostic Factors of Survival and Surgical Extent

Utility of Elective Neck Dissection in Clinically Node-Negative Parotid Malignancy

OBJECTIVE

We sought to investigate the utility of elective neck dissection (END) in clinically node-negative parotid malignancy through the evaluation of factors that are associated with receiving END and survival analysis of patients who received END.

STUDY DESIGN

Retrospective cohort database study.

SETTING

The National Cancer Database (NCDB).

METHODS

The NCDB was used to extract patients with clinically node-negative parotid malignancy. END was defined as having 5 or more lymph nodes examined pathologically, as previously defined in the literature. Univariate and multivariate analyses were used to compare predictors of receiving END, rates of occult metastasis, and survival.

RESULTS

Of the 9405 included patients, 3396 (36.1%) underwent an END. END was most frequently performed for squamous cell carcinoma (SCC) and salivary duct histology. All other histologies were significantly less likely to undergo END compared to SCC (p < .05). Salivary ductal carcinoma and adenocarcinoma had the greatest rates of occult node disease (39.8% and 30.0%, respectively), followed by SCC (29.8%). Kaplan-Meier survival analysis showed a statistically significant increase in 5-year overall survival in patients who received END with poorly differentiated mucoepidermoid (56.2% vs 48.5%, p = .004) along with moderately and poorly differentiated SCC (43.2% vs 34.9%, p = .002; 48.9% vs 36.2%, p < .001, respectively).

CONCLUSION

Histological classification is a benchmark for determining which patients should receive an END. We demonstrated an increase in overall survival in patients who undergo END with poorly differentiated tumors of mucoepidermoid and SCC histology. As such, histology should be considered along with clinical T-stage and rate of occult nodal metastasis to determine eligibility for END.

The role of perineural invasion in parotid malignancy outcomes: A systematic review and meta-analysis

PURPOSE

At present, perineural invasion is used as a histologic indicator of aggressive salivary gland disease. In other head and neck malignancies, perineural invasion impacts staging of cancer lesions and therefore affects treatment options.

OBJECTIVE

To compare survival outcomes in primary parotid malignancies with and without perineural invasion.A systematic review pooled data from the scientific literature in patients with any primary parotid malignancy to investigate the prognosis of those with perineural invasion.

DATA SOURCES

PubMed (Medline), Scopus and Cochrane databases were queried from inception to July 2020 without any initial search constraints. Additional publications were included from review of pertinent articles.

STUDY SELECTION

Our inclusion criteria included primary parotid cancers with reported perineural invasion on survival outcomes. Exclusion criteria were non-English language text, non-human studies, reviews, textbooks, abstracts, case reports and case series. Two authors independently reviewed articles for inclusion. Of the initial 465 records, 83 articles were reviewed in full to yield a final collection of 14 studies.

DATA EXTRACTION AND SYNTHESIS

PRISMA-p guidelines were used in the reporting of our studies. A MOOSE Checklist was also used. MINORS criteria were applied to assess risk of bias. Random-effects models were used to estimate pooled effect sizes. No institutional review board review was needed for our study.

MAIN OUTCOMES AND MEASURES

Primary study outcomes were set prior to data collection and included overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS) and distant-metastasis-free survival (DMFS) in patients with and without perineural invasion.

RESULTS

Fourteen studies contributed to this meta-analysis. Compared to patients without perineural invasion, the pooled rate of mortality (HR = 3.64), time to recurrence (HR = 3.56), disease-specific mortality (HR = 2.77) and distant metastasis (HR = 3.84) was significantly higher for patients with PNI (all p <.001). Controlling for perineural invasion status, no moderator was associated with these survival outcomes (all p >.05). Given the clinical severity of perineural invasion, few studies were null as shown in a panel of publication bias plots.

CONCLUSION

Perineural invasion portends a poor survival outcome in patients with parotid malignancies.

LEVEL OF EVIDENCE: 1

Prognostic indicators in clinically node-negative malignant primary salivary tumours of the parotid: A multicentre experience

OBJECTIVES

Nodal metastasis is an important prognosticator in primary parotid cancers. The management of the clinically node-negative neck is an area lacking consensus. This study investigates the occult nodal metastasis rate, and prognostic indicators in primary parotid cancers.

MATERIALS AND METHODS

We performed a multicentre retrospective case note review of patients diagnosed and treated surgically with curative intent between 1997 and 2020. Demographic, clinic-pathological and follow-up data was recorded.

RESULTS

After exclusions, 334 patients were included for analysis, with a median follow-up of 48 months. The overall rate of occult lymph node metastasis amongst patients undergoing elective neck dissection was 22.4%, with older age, high-grade and more advanced primary tumours being associated with higher rates. On multivariable analysis, age ≥ 60 years (HR = 2.69, p = 0.004), high-grade tumours (HR = 2.70, p = 0.005) and advanced primary tumours (pT3-4, HR = 2.06, p = 0.038) were associated with worse overall survival. Occult nodal metastasis on final pathology was associated with a close-to-significant reduction in regional recurrence free survival (HR = 3.18, p = 0.076).

CONCLUSION

This large series confirms the significant occult lymph node metastasis rate in primary parotid cancer, and demonstrates the importance of primary histology, tumour grade and stage in predicting survival outcome. This data supports the use of elective neck dissection in patients with high-risk tumours.

Is Revision Surgery Necessary for Patients With High Risk of Recurrence After Parotidectomy? A Multicenter Retrospective Study

OBJECTIVES

Close margin is a frequent situation after parotidectomy. The need for systematic prophylactic revision surgery is a question that arises regularly for malignant tumors, as it exposes to a high risk of facial palsy, while oncological benefits are unclear.

STUDY DESIGN

retrospective study.

SETTING

Multicentric.

SUBJECTS AND METHODS

We included all patients operated for systematic revision surgery in case of close margins after parotidectomy for a malignant tumor and analyzed the rate of tumor residue and its risk factors.

RESULTS

A tumor residue was identified in 43.5% of 23 cases, but none in case of initial complete excision with supra-millimetric margins. Invaded lymph nodes were identified in 6 cases, but none in case of low-grade tumors.

CONCLUSIONS

Systematic revision seems mandatory in case of infra-millimetric margins and high-grade tumors or positive lymph node; further studies are needed to confirm whether it can be spared for T1-T2/N0 low-grade tumors, with close margins but complete initial excision.

Impact of Changing Surgical Strategies on Clinical Outcomes in Patients with Parotid Carcinoma: A 53-Year Single-Institution Experience

Background and Objectives: We investigated the clinical outcomes of patients who underwent surgery for parotid carcinoma in a single institution during a 53-year period. This study aimed to estimate the impact of changing the surgical approach to parotid carcinoma on clinical outcomes including the incidence rate of the facial nerve palsy. Materials and Methods: Sixty-seven patients with parotid carcinoma who underwent surgery between 1966 and 2018 were retrospectively reviewed. Group A consisted of 29 patients who underwent surgery from 1966 to 2002, and Group B consisted of 38 patients from 2002 to 2018. Treatment outcomes were estimated. Additionally, candidate prognostic factors of Group B, the current surgical approach group, were evaluated. Results: Partial parotidectomy and total parotidectomy were performed in 35 and 32 patients, respectively. Partial parotidectomy was performed in 4 patients in Group A and 31 patients in Group B, with a predominant increase in Group B. The facial nerve was preserved in 43 patients, among whom 8 in Group A (8/17; 47.1%) and 7 in Group B (7/26; 26.9%) had temporary postoperative facial nerve palsy. Postoperative radiotherapy was performed on 35 patients. The 5-year OS, DSS, and DFS rates for Group A were 77.1%, 79.9%, and 71.5%, respectively. The 5-year OS, DSS, and DFS rates for Group B were 77.1%, 77.1%, and 72.4%, respectively. Clinical T4 stage, clinical N+ stage, stage IV disease, and tumor invasion of the facial nerve were independent prognostic factors in Group B. Conclusions: The incidence of facial nerve palsy in the current surgical approach group decreased compared with that in the previous surgical approach group. The current surgical management and treatment policies for parotid carcinoma have led to improved outcomes.