Lower-Neck Sparing Using Proton Therapy in Patients with Uninvolved Neck Nasopharyngeal Carcinoma: Is It Safe?

Current Status and Future Directions of Proton Therapy for Head and Neck Carcinoma

The growing interest in proton therapy (PT) in recent decades is justified by the evidence that protons dose distribution allows maximal dose release at the tumor depth followed by sharp distal dose fall-off. But, in the holistic management of head and neck cancer (HNC), limiting the potential of PT to a mere dosimetric advantage appears reductive. Indeed, the precise targeting of PT may help evaluate the effectiveness of de-escalation strategies, especially for patients with human papillomavirus associated-oropharyngeal cancer (OPC) and nasopharyngeal cancer (NPC). Furthermore, PT could have potentially greater immunogenic effects than conventional photon therapy, possibly enhancing both the radiotherapy (RT) capability to activate anti-tumor immune response and the effectiveness of immunotherapy drugs. Based on these premises, the aim of the present paper is to conduct a narrative review reporting the safety and efficacy of PT compared to photon RT focusing on NPC and OPC. We also provide a snapshot of ongoing clinical trials comparing PT with photon RT for these two clinical scenarios. Finally, we discuss new insights that may further develop clinical research on PT for HNC.

Distribution of regional lymph nodes metastasis in 870 cases of nasopharyngeal carcinoma and the suggestions for individualized elective prophylactic neck irradiation with intensity-modulated radiotherapy

PURPOSE

To explore the feasibility of individualized elective prophylactic neck irradiation (iEPNI) for optimizing current approach by investigating metastatic lymph nodes (LNs) distribution in nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

Records of 870 NPC patients without distant metastasis in Hunan Cancer Hospital from January 2019 to December 2019 were reviewed. LNs' locations were identified based on the 2013 guidelines. The intra-regional lymphatic drainage (IRLD) areas included Station 1st (level VIIa and II), Station 2nd (level III and Va), and Station 3rd (level IV, Vb, and Vc). Other levels were categorized as extra-regional areas.

RESULTS

Among the 870 patients, 94.5% cases exhibited LNs metastasis, including unilateral metastasis in 198 patients and bilateral metastasis in 624 patients. In the whole cohort, the most common involved IRLD areas were level IIb (87.1%), VIIa (80.0%), IIa (61.8%), Va (30.6%), IV (21.4%), Vb (8.9%), and Vc (1.1%). Besides, rates of LNs metastasis in Station 1st, 2nd, and 3rd were 94.3%, 61.1%, and 22.9%, respectively. Only four patients (4, 0.5%) revealed skipping metastasis among the three stations.

CONCLUSIONS

Lymph node metastasis follows an organized pattern from Station 1st to 3rd with scarce skipping metastasis. A potential iEPNI strategy of prophylactic neck irradiation to the ipsilateral latter node-negative station appears promising in NPC patients. Further prospective investigations are warranted to validate the approach.

Upper-neck irradiation versus standard whole-neck irradiation in nasopharyngeal carcinoma: A systematic review and meta-analysis

PURPOSE

To evaluate the role of upper-neck irradiation versus standard whole-neck irradiation in patients with N0-1 nasopharyngeal carcinoma.

METHODS

We conducted a PRISMA guideline based systematic review and meta-analysis. Randomized clinical trials assessing upper-neck irradiation versus whole-neck irradiation with or without chemotherapy in non-metastatic N0-1 nasopharyngeal carcinoma patients were identified. The studies were searched on the PubMed, Embase and Cochrane library up to March 2022. Survival outcomes, including overall survival, distant metastasis-free survival and relapse-free survival, and toxicities rate were evaluated.

RESULTS

There were two randomized clinical trials with 747 samples finally included. Upper-neck irradiation had similar overall survival (hazard ratio = 0.69, 95% confidence interval = 0.37-1.30), distant metastasis-free survival (hazard ratio = 0.92, 95% confidence interval = 0.53-1.60) and relapse-free survival (risk ratio = 1.03, 95% confidence interval = 0.69-1.55) compared to whole-neck irradiation. No differences in both acute and late toxicities were recorded between upper-neck irradiation and whole-neck irradiation.

CONCLUSION

This meta-analysis supports the potential role of upper-neck irradiation in this population of patients. Further research is needed to confirm results.