Recurrence of nasopharyngeal carcinoma in the parotid region after parotid-gland-sparing radiotherapy

Clinical treatment considerations in the intensity-modulated radiotherapy era for parotid lymph node metastasis in patients with nasopharyngeal carcinoma

PURPOSE

No specific irradiation guidelines have been proposed for parotid lymph node (PLN) metastasis in patients with nasopharyngeal carcinoma (NPC). This study aimed to explore the dose prescription and target delineation for PLN metastasis in patients with NPC.

METHODS

With the NPC database from a big-data platform, 10,685 patients with primarily diagnosed, non-distant metastatic, histologically proven NPC and treated with intensity modulated radiotherapy (IMRT) at our center from 2008 to 2019 were reviewed and those with PLN metastasis were enrolled in this study. Dosimetry parameters were collected from the dose-volume histograms (DVH). The primary endpoint was overall survival (OS). Least absolute shrinkage and selection operator regression (LASSO) was operated for variable selection. Multivariate Cox regression analysis was applied to identify the independent prognostic factors.

RESULTS

PLN metastases were identified in 275/10685 (2.5%) patients. Of 367 positive PLN, 199 were in superficial intra-parotid, followed by 70 in deep intra-parotid, 54 in subparotid and 44 in subcutaneous pre-auricular. Better survival outcome was observed in PLN-radical IMRT group, compared with PLN-sparing group. In 190 patients received PLN-radical IMRT, multivariate analysis revealed that D95% of level VIII > 55 Gy was an independent beneficial prognostic factor for overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS), and parotid relapse-free survival (PRFS).

CONCLUSION

Based on the distribution pattern of PLN metastasis in NPC and the result of dose-finding study, involving the ipsilateral level VIII into low-risk clinical target volume (CTV2) is recommended for NPC with PLN metastasis.

A prediction model for xerostomia in locoregionally advanced nasopharyngeal carcinoma patients receiving radical radiotherapy

Background

This study was to evaluate the predictors of xerostomia and Grade 3 xerostomia in locoregionally advanced nasopharyngeal carcinoma (NPC) patients receiving radical radiotherapy and establish prediction models for xerostomia and Grade 3 xerostomia based on the predictors.

Methods

Totally, 365 patients with locoregionally advanced NPC who underwent radical radiotherapy were randomly divided into the training set (n = 255) and the testing set (n = 110) at a ratio of 7:3. All variables were included in the least absolute shrinkage and selection operator regression to screen out the potential predictors for xerostomia as well as the Grade 3 xerostomia in locoregionally advanced NPC patients receiving radical radiotherapy. The random forest (RF), a decision tree classifier (DTC), and extreme-gradient boosting (XGB) models were constructed. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), area under the curve (AUC) and accuracy were analyzed to evaluate the predictive performance of the models.

Results

In the RF model for predicting xerostomia, the sensitivity was 1.000 (95%CI 1.000–1.000), the PPV was 0.990 (95%CI 0.975–1.000), the NPV was 1.000 (95%CI 1.000–1.000), the AUC was 0.999 (95%CI 0.997–1.000) and the accuracy was 0.992 (95%CI 0.981–1.000) in the training set. The sensitivity was 0.933 (95%CI 0.880–0.985), the PPV was 0.933 (95%CI 0.880–0.985), and the AUC was 0.915 (95%CI 0.860–0.970) in the testing set. Hypertension, age, total radiotherapy dose, dose at 50% of the left parotid volume, mean dose to right parotid gland, mean dose to oral cavity, and course of induction chemotherapy were important variables associated with the risk of xerostomia in locoregionally advanced NPC patients receiving radical radiotherapy. The AUC of DTC model for predicting xerostomia was 0.769 (95%CI 0.666–0.872) in the testing set. The AUC of the XGB model for predicting xerostomia was 0.834 (0.753–0.916) in the testing set. The RF model showed the good predictive ability with the AUC of 0.986 (95%CI 0.972–1.000) in the training set, and 0.766 (95%CI 0.626–0.905) in the testing set for identifying patients who at high risk of Grade 3 xerostomia in those with high risk of xerostomia.

Conclusions

An RF model for predicting xerostomia in locoregionally advanced NPC patients receiving radical radiotherapy and an RF model for predicting Grade 3 xerostomia in those with high risk of xerostomia showed good predictive ability.

Treatment of persistent/recurrent nodal disease in nasopharyngeal cancer

PURPOSE OF REVIEW

Persistent or recurrent disease in the neck lymphatics is an unusual pattern of failure in nasopharyngeal carcinoma (NPC) after definitive radiotherapy or chemoradiotherapy. The purpose of this review is to critically synthesize the current knowledge regarding salvage treatment of this unique form of failure in NPC.

RECENT FINDINGS

Surgery in the form of radical neck dissection has been established as the standard salvage treatment with 5-year regional control of 60--86%. Recent shift in paradigm has resulted in the use of modified or selective neck dissection as salvage surgery in some centers. Risk factors for poor survival outcome include recurrent nodal disease, number of involved lymph nodes, extracapsular extension, high lymph node ratio, and positive resection margin. There are no well controlled studies on the role of additional radiotherapy or chemotherapy to improve local control or survival after salvage neck dissection in this group of patients with regional failure.

SUMMARY

There is limited literature regarding the extent of surgical dissection in treating nodal persistent or recurrent disease. Prospective studies are also needed to determine whether adjuvant therapy improves treatment outcomes.

Establishment and Validation of a Nomogram for Nasopharyngeal Carcinoma Patients Concerning the Prognostic Effect of Parotid Lymph Node Metastases

Purpose

The prognosis of nasopharyngeal carcinoma (NPC) patients with parotid lymph node (PLN) metastasis remains unclear. This study was performed to investigate the prognostic significance and optimal staging category of PLN metastasis and develop a nomogram for estimating individual risk.

Materials and Methods

Clinical data of 7,084 non-metastatic NPC patients were retrospectively reviewed. Overall survival (OS) was the primary endpoint. A nomogram was established based on the Cox proportional hazards regression model. The accuracy and calibration ability of this nomogram was evaluated by C-index and calibration curves with bootstrap validation.

Result

Totally, 164/7,084 NPC patients (2.3%) presented with PLNs. Multivariate analyses showed that PLN metastasis was a negative prognostic factor for OS, progression-free survival (PFS), distant metastasis-free survival (DMFS), and locoregional relapse-free survival (LRFS). Patients with PLN metastasis had a worse prognosis than N3 disease. Five independent prognostic factors were included in the nomogram, which showed a C-index of 0.743. The calibration curves for probability of 3- and 5-year OS indicated satisfactory agreement between nomogram-based prediction and actual observation. All results were confirmed in the validation cohort.

Conclusion

NPC patient with PLN metastasis had poorer survival outcome (OS, PFS, DMFS, and LRFS) than N3 disease. We developed a nomogram to provide individual prediction of OS for patients with PLN metastasis.

Investigation of long-term survival outcomes and failure patterns of patients with nasopharyngeal carcinoma receiving intensity-modulated radiotherapy: a retrospective analysis

Intensity-modulated radiotherapy (IMRT) has replaced the conventional radiotherapy (2D-RT) and improved clinical efficacy in Nasopharyngeal Carcinoma (NPC) patients. In the present study, we retrospectively analyzed the clinical characteristics of patients with NPC treated with IMRT to assess the long-term survival outcomes and failure patterns. Of the 527 patients, One hundred and twenty-one patients experienced treatment failure, 86 patients developed distant metastases, and 12 patients developed a second primary tumor. The local and regional recurrence rates were 31.4% and 14.0%, respectively. The 5-year overall survival (OS), progression-free survival (PFS), local recurrence-free survival (LRFS), regional relapse-free survival (RRFS), and distant metastatic relapse-free survival (DMFS) rates were 80.9%, 75.6%, 91.7%, 96.2%, and 83.0%, respectively. The 5-year LRFS rates of Stage T1-4 patients were 100.0%, 93.1%, 92.0%, and 85.8%, respectively. The 5-year DMFS rates of Stage N0-3 patients were 95.0%, 86.1%, 79.5%, and 67.2%, respectively. Multivariate analysis showed age and T-stage were independent predictors of OS, T-stage was an independent predictor of LRFS, and age and N-stage were independent predictors of PFS and DMFS.

In summary, the improved treatment results with IMRT are primarily due to the achievement of a higher local tumor control rate and OS in NPC patients. However, distant metastasis was the most commonly observed failure pattern after treatment. These results provide deep insights about the value of IMRT in the treatment and prognosis of NPC patients.

Role of diffusion-weighted imaging in the discrimination of benign and metastatic parotid area lymph nodes in patients with nasopharyngeal carcinoma

To assess the utility of apparent diffusion coefficient (ADC) determined on diffusion-weighted MR imaging (DWI) to differentiate between benign and malignant parotid area lymph nodes (PLN) in nasopharyngeal carcinoma (NPC) patients. Thirty-nine consecutive NPC patients with a total of 40 enlarged, biopsied PLNs underwent DWI examination. ADC values for benign and malignant PLNs were measured and compared. Receiver operating characteristic (ROC) curve analysis was to evaluate the optimal threshold level of ADC values for metastatic PLNs. The kappa was to assess the degree of agreement between histopathological diagnoses and ADC values, or imaging features of PLNs on MRI. We found the mean ADC value for benign PLNs was markedly higher than malignant PLNs. A threshold ADC of 1.01 × 10⁻³ mm²/s was associated with a sensitivity of 85.7% and a specificity of 72.7% (area under the curve: 0.84). A moderate agreement was observed between the histopathological diagnosis and the threshold of ADC value (k value: 0.483). However, short axis diameter, necrosis, extranodal extension, and regional grouping of PLNs on MRI showed only a fair agreement with the histopathological diagnosis (k value: 0.257, 0.305, 0.276, and 0.205, respectively). Therefore, DWI may be a promising technique to differentiate metastatic from benign PLNs.

Prognostic effect of parotid area lymph node metastases after preliminary diagnosis of nasopharyngeal carcinoma: a propensity score matching study

Parotid area lymph node (PLN) metastasis in nasopharyngeal carcinoma (NPC) is rare, and its prognosis remains largely unknown. Our study aimed to investigate the prognostic value and staging categories of PLN metastasis in patients with NPC and treated with intensity‐modulated radiation therapy (IMRT), to provide a reference for clinical treatment for NPC with PLN metastasis. Records for 1616 untreated NPC patients without distant metastasis was retrospectively reviewed. All patients underwent magnetic resonance imaging (MRI) examination prior to treatment and then received IMRT as their primary treatment. Forty‐five NPC patients (2.8%) showed initial PLN metastasis on follow‐up MRI. PLN metastasis was significantly associated with the N classification and clinical stage. Univariate analysis showed that PLN metastasis had an unfavorable influence on overall survival (OS), progression‐free survival (PFS), distant metastasis‐free survival (DMFS), and regional relapse‐free survival (RRFS) in NPC patients. Using propensity score matching (PSM) to calibrate selection bias and confounding bias, it was observed that PLN metastasis remained an adverse prognostic factor for OS, PFS, DMFS, and RRFS. Furthermore, the 5‐year DMFS and RRFS curves for PLN metastasis were significantly separated from that for N2 disease but crossed that for N3 disease. Therefore, PLN metastasis was found to be an adverse prognostic factor for NPC and to be associated with the same DMFS as N3 disease. Therefore, more aggressive therapeutic strategies consistent with those for N3 disease are recommended for NPC with PLN metastasis to reduce distant metastasis.

Analysis of rare periparotid recurrence after parotid gland-sparing intensity-modulated radiotherapy for nasopharyngeal carcinoma

PURPOSE

Periparotid recurrence is an uncommon phenomenon after intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma. This study aimed to discuss the clinical characteristics, reasonable causes and feasible therapeutic modalities of patients with nasopharyngeal carcinoma and periparotid recurrence.

PATIENTS AND METHODS

The medical records of 1852 patients with non-metastatic nasopharyngeal carcinoma treated with initial IMRT between January 2008 and December 2012 were retrospectively reviewed, and nine patients were finally found to have developed periparotid recurrence after IMRT. After periparotid failure, four received radiotherapy and chemotherapy, two had surgery, two had surgery and adjuvant radiotherapy or chemotherapy, and one received radiotherapy alone.

RESULT

The incidence rate of periparotid recurrence was 4.9‰. According to pretreatment magnetic resonance imaging (MRI) scans, all patients had both ipsilateral retropharyngeal lymph nodes metastasis with 66.7% of extracapsular spread and level II lymphadenopathy with all extracapsular spread. The median time interval to periparotid failure was 14.8 months, and six patients were found to have a relapse in the primary sites of unsuspicious parotid nodules. After a median follow-up of 46.4 months, five patients developed distant metastasis, three of them developed local failure. In addition, one developed regional failure, one developed locoregional recurrence, and only one was alive without evidence of disease at the last follow-up.

CONCLUSION

Periparotid recurrences are rare after definitive IMRT for nasopharyngeal carcinoma. However, patients with ipsilateral retropharyngeal lymph nodes or level II nodal extracapsular spread on pretreatment MRI could be suspicious of metastatic periparotid nodules. Distant metastases were the main treatment failure despite a combination of several salvage treatment of periparotid recurrence. More effective chemotherapy should be explored.

Parotid area lymph node metastases from preliminarily diagnosed patients with nasopharyngeal carcinoma: report on tumor characteristics and oncologic outcomes

The parotid area lymph node (PLN) is an uncommon site of metastasis originating from nasopharyngeal carcinoma (NPC). The study aimed to investigate clinical characteristics and outcomes of patients with preliminarily diagnosed NPC with PLN metastases. Here we retrospectively reviewed Magnetic resonance imaging (MRI) scans of 2221 patients with untreated nonmetastatic NPC who received intensity-modulated radiation therapy (IMRT). Finally, 64 (2.9%) patients were identified with PLN metastases, of which, 34 received PLN-sparing IMRT and 30 received PLN-radical IMRT. We also found that 42.2% had N3 disease and 95.3% had stages III-IVb. PLN metastases on MRI were characterized by ipsilateral retropharyngeal lymph node (RLN) or level II nodal extracapsular spread (ECS), ipsilateral giant cervical nodes, ipsilateral parapharyngeal extension, or solitary parotid metastasis. The 5-year overall survival, distant metastasis-free survival, regional relapse-free survival, and parotid relapse-free survival rates were 70.4%, 64.3%, 76.7%, and 87.9%, respectively. Distant metastases were the main cause of treatment failure and death. Using PLN-sparing IMRT, sparing PLN with minimal axial diameter of <10 mm, could increase the risk of parotid recurrence. However, it was not an independent prognostic factor. N classification and concurrent-based chemotherapy were almost statistically significant for distant failure and death. Overall, we demonstrated that the PLN metastases might be derived from RLN or level II nodal ECS, giant cervical nodes in a retrograde fashion, or parapharyngeal extension. Sparing PLN of <10 mm by IMRT should consider the risk of parotid recurrence. Distant metastases remained the dominant treatment failure. Further effective systemic chemotherapy should be explored.

Prognostic value of parotid lymph node metastasis in patients with nasopharyngeal carcinoma receiving intensity-modulated radiotherapy

The prognostic value and staging category of parotid lymph node (PLN) metastasis in nasopharyngeal carcinoma (NPC) remain unknown. We retrospectively reviewed MRI scans and medical records for 1811 NPC patients who received intensity-modulated radiotherapy. The diagnosis of PLN metastasis was mainly based on MRI follow-up. Twenty-five positive PLNs in 21/1811 patients were identified; the incidence of PLN metastasis was 1.2%. PLN metastasis was significantly associated with advanced N-category and stage. Ten of the 21 patients received irradiation of the involved PLNs; the PLN recurrence rate was significantly higher for patients who received no irradiation; thus only patients with irradiated PLN were included in prognostic analyses. PLN metastasis was associated with significantly poorer progression-free survival, overall survival and distant metastasis-free survival (DMFS), but not regional or local relapse-free survival, in univariate analysis. In multivariate analysis, PLN metastasis was also significantly associated with poor DMFS. PLN involvement had a significantly higher hazard ratio (HR) for distant failure than N2 disease and similar HR to N3 disease. In conclusion, PLN metastasis is rare in NPC and was associated with similarly poor DMFS as N3 disease. PLN metastasis should be suspected in advanced nodal disease, but diagnosed with care before administering aggressive treatment.

Recurrence of nasopharyngeal carcinoma in the parotid region after definitive intensity-modulated radiotherapy

PURPOSE

To discuss the clinical characteristics and management of periparotid recurrence of nasopharyngeal carcinoma after definitive intensity-modulated radiotherapy.

PATIENTS AND METHODS

The authors retrospectively reviewed the charts of 716 patients with nasopharyngeal carcinoma who underwent intensity-modulated radiotherapy at their center from January 2005 through December 2010. Disease recurred in a spared parotid gland in 10 patients (1.4%). After periparotid recurrence, 4 patients received surgery alone, 1 patient received radiotherapy alone, 2 patients received chemotherapy alone, 2 patients received surgery plus chemotherapy, and 1 patient received surgery plus radiotherapy.

RESULTS

After a median follow-up of 42.6 months (19.8 to 86.0 months), 4 patients died of tumor progression. The median survival time after periparotid recurrence was 25.1 months (5.0 to 74.5 months).

CONCLUSIONS

Periparotid recurrence is an uncommon pattern of failure after definitive intensity-modulated radiotherapy for nasopharyngeal carcinoma, and there were some long-term survivors in this patient population after salvage treatment.

Swallowing dysfunction in head and neck cancer patients treated by radiotherapy: review and recommendations of the supportive task group of the Italian Association of Radiation Oncology

PURPOSE

Dysphagia is a debilitating complication in head and neck cancer patients (HNCPs) that may cause a high mortality rate for aspiration pneumonia. The aims of this paper were to summarize the normal swallowing mechanism focusing on its anatomo-physiology, to review the relevant literature in order to identify the main causes of dysphagia in HNCPs and to develop recommendations to be adopted for radiation oncology patients. The chemotherapy and surgery considerations on this topic were reported in recommendations only when they were supposed to increase the adverse effects of radiotherapy on dysphagia.

MATERIALS AND METHODS

The review of literature was focused on studies reporting dysphagia as a pre-treatment evaluation and as cancer and cancer therapy related side-effects, respectively. Relevant literature through the primary literature search and by articles identified in references was considered. The members of the group discussed the results and elaborated recommendations according to the Oxford CRBM levels of evidence and recommendations. The recommendations were revised by external Radiation Oncology, Ear Nose and Throat (ENT), Medical Oncology and Speech Language Pathology (SLP) experts.

RESULTS

Recommendations on pre-treatment assessment and on patients submitted to radiotherapy were given. The effects of concurrent therapies (i.e. surgery or chemotherapy) were taken into account.

CONCLUSIONS

In HNCPs treatment, disease control has to be considered in tandem with functional impact on swallowing function. SLPs should be included in a multidisciplinary approach to head and neck cancer.