Feasibility of ipsilateral lower neck sparing irradiation for unilateral or bilateral neck node-negative nasopharyngeal carcinoma: systemic review and meta-analysis of 2, 521 patients

Optimizing Cervical Target Volume in Patients with Nasopharyngeal Cancer Based On Nodal Drainage Distance

PURPOSE

To determine the potential nodal drainage distances of nasopharyngeal carcinoma (NPC) by investigating spatial distribution of metastatic lymph nodes (LN).

EXPERIMENTAL DESIGN

Patients with NPC harboring at least two ipsilateral metastatic LNs were enrolled. LN spreading distances were analyzed in nonrestricted direction, cranial-to-caudal direction, and between the two most caudal LNs. Euclidean distance (ED) and vertical distance (VD) between any two LNs were computed. The nearest-neighbor ED and VD covering 95% of LNs or patients (p95-ED and p95-VD) were considered drainage distances, and were further validated by independent internal and external cohorts with recurrent LNs.

RESULTS

In all, 5,836 metastatic LNs in 948 patients were contoured. Corresponding to the three scenarios, per-LN level, the p95-EDs were 2.83, 3.28, and 3.55 cm, and p95-VDs were 2.17, 2.32, and 2.63 cm, respectively. Per-patient level, the p95-EDs were 3.25, 3.95, and 3.81 cm, and p95-VDs were 2.67, 2.81, and 2.73 cm, respectively. In internal validation, over 95% of recurred LNs occurred within ED of 2.91 cm and VD of 0.82 cm to the neighbor LN, and the corresponding distances in external validation were 2.77 and 0.67 cm, respectively.

CONCLUSIONS

In NPC, the maximum LN drainage distance was 3.95 cm without considering the direction. Specifically, in cranial-to-caudal direction, the sufficient vertical drainage distance was 2.81 cm, indicating that a 3-cm extension from the most inferior node may be rational as caudal border of the prophylactic clinical target volume (CTV). These findings promote in-depth understanding of nodal spreading patterns, uncovering paramount evidence for individualized CTV.

Selectively sparing of the supraclavicular area during intensity-modulated radiotherapy in nasopharyngeal carcinoma: A double-center observation study

BACKGROUND AND PURPOSE

This study was aimed at evaluating the feasibility of sparing the supraclavicular area, namely levels IVb and Vc, during intensity-modulated radiotherapy (IMRT) in nasopharyngeal carcinoma (NPC) patients with N1-2 disease[except N1 disease with purely restropharyngeal lymph nodes(RPN) involvement], and providing a basis for the revision of International Guideline for the delineation of the clinical target volume (CTV).

PATIENTS AND MATERIALS

Patients with NPC (stage TanyN1-2M0) diagnosed pathologically in Fujian Cancer Hospital (Center 1, Only Lin SJ's attending group) from January 2014 to March 2018 and Jiangxi Cancer Hospital(Center 2) from January 2014 to December 2015 were included. According to our principle, the supraclavicular area (levels IVb and Vc) were excluded from the CTVnd. Survival outcomes focused on regional recurrence-free survival (RRFS) and recurrence rates of levels IVb and Vc were analysed.

RESULTS

A total of 672 eligible patients were recruited (Center 1, n = 362; Center 2, n = 310). There was no significant difference in 5-year RRFS (97.33 % vs. 97.24 %, p = 0.980), overall survival (OS) (89.14 % vs. 88.56 %, p = 0.327), local recurrence-free survival (LRFS) (94.90 % vs. 95.30 %, p = 0.593) and distant metastasis-free survival (DMFS) (89.38 % vs. 86.60 %, p = 0.130) between Center 1 and Center 2. Twenty patients developed regional failure (median: 36 months), among them, only one case (0.15 %) was recorded as levels IVb and Vc recurrence.

CONCLUSION

Omitting the supraclavicular area (levels IVb and Vc) during IMRT should be safe and feasible for N1-2 disease (except N1 disease with purely RPN involvement). Well-designed multicenter prospective trials should be conducted to confirm our findings.

Efficacy and toxicities of elective upper-neck irradiation versus whole-neck irradiation of the uninvolved neck in patients with nasopharyngeal carcinoma: A meta-analysis

BACKGROUND

This meta-analysis aimed to investigate the efficacy and radiation-related toxicities of upper-neck irradiation (UNI) over whole-neck irradiation (WNI) in patients with unilateral or bilateral node-negative nasopharyngeal carcinoma.

METHODS

We conducted a systematic review to identify studies comparing survival and toxicities between UNI and WNI by searching key databases up to Aug 2022. Hazard ratios (HRs) with 95% confidence intervals (CIs) for regional recurrence-free survival (RRFS), local recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS) were pooled using R 4.0.5. Risk ratios (RRs) for acute and late radiation-related toxicities were also pooled. Subgroup analyses according to nodal status, radiotherapy techniques, and study type were conducted.

RESULTS

Eight studies enrolling 2568 patients were included. Patients who received UNI showed similar RRFS (HR 0.99, 95% CI 0.57-1.74, P = 0.975), LRFS (HR 0.86, 95% CI 0.53-1.41, P = 0.559), DMFS (HR 0.90, 95% CI 0.63-1.29, P = 0.581), PFS (1.10, 95% CI 0.73-1.67, P = 0.642), and OS (1.03, 95% CI 0.77-1.37, P = 0.866) compared with WNI. When stratified by nodal status, the pooled HRs for RRFS in patient subgroups with stage N0 disease, stage N1 with only retropharyngeal lymph nodes metastasis, and unilateral cervical lymph node metastasis were 0.46 (95% CI 0.04-5.16, P = 0.529), 1.12 (95% CI 0.29-4.38, P = 0.872), and 1.02 (95% CI 0.48-2.16, P = 0.968) respectively, none of which reached statistical significance. UNI was associated with lower incidences of grade 1-2 hypothyroidism (RR 0.75, 95% CI 0.57-0.97, P = 0.031) and grade 1-2 dysphagia (RR 0.58, 95% CI 0.42-0.80, P < 0.001) compared with WNI.

CONCLUSION

UNI had similar efficacy and fewer toxicities compared with WNI for patients with unilateral or bilateral node-negative nasopharyngeal carcinoma. The lower-neck sparing of the uninvolved neck is a valid option for N0, N1, and even unilateral N3 diseases in nasopharyngeal carcinoma.

Involved site radiation therapy in stage I-III nasopharyngeal carcinoma with limited lymph node burden (ISRT-NPC) or elective region irradiation: a study protocol for a multicenter non-inferiority randomized controlled phase III clinical trial

BACKGROUND

Current radiotherapy guidelines and consensus statements uniformly recommend elective region irradiation (ERI) as the standard strategy for nasopharyngeal carcinoma (NPC). However, given the scarcity of skip-metastasis, the improved assessment accuracy of nodal involvement, and the striking advancements in chemotherapy for NPC, a one-fits-all delineation scheme for clinical target volumes of the nodal region (CTVn) may not be appropriate anymore, and modifications of the CTVn delineation strategy may be warranted. Involved site irradiation (ISI) covering merely the initially involved nodal site and potential extranodal extension has been confirmed to be as effective as ERI with decreased radiation-related toxicities in some malignancies, but has not yet been investigated in NPC. This study aims to compare the regional control, survival outcomes, radiation-related toxicities, and quality of life (QoL) of ISI with conventional ERI in NPC patients with a limited nodal burden.

METHODS

ISRT-NPC is a prospective, multicenter, open-label, noninferiority, phase III randomized controlled trial. A total of 414 patients will be randomly assigned in a 1:1 ratio to receive ISI or ERI. Randomization will be stratified by institution scale and N stage. Generally, in the ISI group, the high-risk CTV1 (dose: 60 Gy) includes a 1-cm expansion of the positive LN as well as the VIIa and the retrostyloid space above the bilateral transverse process of the atlantoaxial spine (C1), regardless of N status. The low-risk CTV2 (dose: 50 Gy) covers the cervical nodal region with a 3-cm caudal expansion below the transverse process of C1 for N0 disease and a 3-cm expansion below the positive LN for positive LNs.

DISCUSSION

The results of this trial are expected to confirm that ISI is a non-inferior strategy to ERI in stage I-III patients with low LN burden, enabling the minimization of treatment-related toxicity and improvement of long-term QoL without compromising regional control.

TRIAL REGISTRATION

ClinicalTrails.gov, NCT05145660. Registered December 6, 2021.

Metastatic patterns of level II-V cervical lymph nodes assessed per vertebral levels in nasopharyngeal carcinoma

BACKGROUND AND PURPOSE

The current cervical lymph nodes classification system is not perfectly reasonable for radiotherapy of nasopharyngeal carcinoma (NPC). This study aimed to determine the metastatic patterns of level II-V lymph nodes in NPC by using vertebrae as anatomical landmarks.

MATERIALS AND METHODS

Four hundred and forty node-positive NPC patients were selected. Metastatic lymph nodes were diagnosed using positron emission tomography/computed tomography scan or magnetic resonance imaging. We evaluated univariate and multivariate logistic correlations between the vertebral levels of metastatic level II-V lymph nodes.

RESULTS

The metastasis rate of level II-V lymph nodes gradually decreased from C2 (66.5%) and C3 (68.2%) to T1 (4.1%) vertebral levels. When assessed per vertebral level, 98.4% were non-skip metastasis. The interval of vertebral levels and distance between the inferior border of the tumor and the metastatic lymph nodes were similar in N1 and N2 patients. Univariate correlation analysis showed the metastasis of level II-V lymph nodes at each vertebral level was associated with the metastasis at any other vertebral level. In the multivariate analysis, metastasis at any one of the C2-C7 vertebral levels strongly and positively correlated with metastasis at two adjacent vertebral levels, including one level above and one below.

CONCLUSION

This is the first study to report the distribution and non-skip metastatic patterns of level II-V lymph nodes assessed per vertebral levels in NPC. The low-risk clinical target volume could be reduced to two vertebral levels below the vertebral level of the metastatic level II-V nodes when both imaging modalities are available.

Upper-Neck Versus Whole-Neck Irradiation at the Contralateral Uninvolved Neck in Patients With Unilateral N3 Nasopharyngeal Carcinoma

PURPOSE

Upper-neck irradiation (UNI) at the uninvolved neck has shown similar regional relapse-free survival as standard whole-neck irradiation (WNI) in patients with N0-1 nasopharyngeal carcinoma. However, whether UNI at the contralateral uninvolved neck is feasible in unilateral N3 disease, defined as >6 cm and/or below the caudal border of the cricoid cartilage, remains unclear.

METHODS AND MATERIALS

Data for 291 patients with nasopharyngeal carcinoma with unilateral N3 disease who were treated with intensity modulated radiation therapy from 2009 to 2015 were retrospectively analyzed. Among them, 190 received bilateral WNI (WNI group); the remaining 101 received WNI at the involved neck and UNI at the contralateral uninvolved neck (UNI group). Survival rates were estimated using the Kaplan-Meier method, and differences between groups were compared using the log rank tests.

RESULTS

The median follow-up was 79.4 months (interquartile range, 56.0-89.3). Twenty-five patients had regional lymph node relapses (UNI: 10.9%, 11/101 vs WNI: 7.4%, 14/190; P = .31). Of these, 23 patients relapsed within the previously involved neck regions, while only 2 patients had relapses in the contralateral uninvolved neck (1 each in the UNI and WNI groups). Five-year regional relapse-free survival rates were similar between groups (89.7% vs 92.7%, P = .29). Similar between-group findings were also observed for 5-year overall survival (76.1% vs 80.4%, P = .40), distant metastasis-free survival (74.9% vs 79.2%, P = .44), and local relapse-free survival (95.6% vs 94.7%, P = .64). Furthermore, oncologic outcomes in subgroup and multivariable analyses were similar between groups.

CONCLUSIONS

Regional control and survival outcomes were comparable in UNI at the contralateral uninvolved neck and standard WNI in patients with nasopharyngeal carcinoma with unilateral N3 disease. Our findings provide evidence for future radiation therapy guidelines of nasopharyngeal carcinoma.

Retrospective analysis of adjuvant radiotherapy in oral cavity or oropharyngeal cancer: Feasibility of omitting lower-neck irradiation

Objectives

Adjuvant radiotherapy is the standard of care in locally advanced head and neck cancers. The radiation field is correlated with the surgical field in the adjuvant radiotherapy setting; therefore, tailoring the irradiation field is reasonable.

Materials and methods

We retrospectively analyzed patients with oral cavity and oropharyngeal cancers included in the cancer registry between 2015 and 2019 in the study hospital. Patients who underwent whole-neck irradiation (WNI) were compared with those who underwent lower-neck–sparing (LNS) irradiation.

Results

A total of 167 patients with oral cavity and oropharyngeal cancers were included in the study. Cancer recurrence was recorded in 33% of the patients. The rate of recurrence of oral cavity and oropharyngeal cancer at neck level IV was 8%. The 2-year incidence of level IV recurrence was lower in the WNI group than in the LNS group (2% vs. 10%; p = 0.04). The 2-year disease-free survival rates were 75% and 63% in the WNI and LNS groups, respectively (p = 0.08).

Conclusion

The rate of level IV recurrence was higher in the LNS group than in the WNI group. Trends of improvement in disease-free survival with lower-neck irradiation suggested that it is premature to consider LNS irradiation as daily practice in patients with oral cavity and oropharyngeal cancer.

The Chinese Society of Clinical Oncology (CSCO) clinical guidelines for the diagnosis and treatment of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant epithelial tumor originating in the nasopharynx and has a high incidence in Southeast Asia and North Africa. To develop these comprehensive guidelines for the diagnosis and management of NPC, the Chinese Society of Clinical Oncology (CSCO) arranged a multi‐disciplinary team comprising of experts from all sub‐specialties of NPC to write, discuss, and revise the guidelines. Based on the findings of evidence‐based medicine in China and abroad, domestic experts have iteratively developed these guidelines to provide proper management of NPC. Overall, the guidelines describe the screening, clinical and pathological diagnosis, staging and risk assessment, therapies, and follow‐up of NPC, which aim to improve the management of NPC.

The next decade of clinical trials in locoregionally advanced nasopharyngeal carcinoma

Clinical trials are powerful weapons in the battle against nasopharyngeal carcinoma (NPC). Based on clinical trials conducted in the past two decades, concurrent chemoradiotherapy combined with adjuvant chemotherapy or induction chemotherapy has been recommended as the standard treatment for locoregionally advanced NPC in various guidelines. However, there remain shortcomings concerning current treatment modalities that should be refined in future research. In this article, we review the achievements of published clinical trials for locoregionally advanced NPC and propose future directions for subsequent clinical trials. We believe that refinement of current regimens of chemotherapy, de-intensification of treatment for specific groups of patients, developing personalized treatment based on predictors ( e.g. applying plasma Epstein-Barr virus DNA) and investigating novel therapies, such as targeted therapy and immunotherapy, should be applied with the highest priority when designing clinical trials for locoregionally advanced NPC in the next decade.

Thyroid dose-volume thresholds for the risk of radiation-related hypothyroidism in nasopharyngeal carcinoma treated with intensity-modulated radiotherapy-A single-institution study

BACKGROUND

To identify thyroid dose-volume thresholds for radiotherapy (RT)-related hypothyroidism (HT) in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated RT (IMRT). In this way, we desired to guide the design of treatment plans and, finally, lower HT prevalence.

METHODS

In total, 345 NPC patients treated with IMRT were evaluated retrospectively during a median follow-up of 45.2 (range, 11.3-64.9) months. Serum-based assessments of thyroid function before and after IMRT were monitored periodically. Thyroid dose-volume parameters were analyzed for their association with HT risk.

RESULTS

In total, 44.1% of patients (152/345) developed primary HT. Analyses of thyroid dose-volume parameters identified a stringent dose-volume histogram (DVH) threshold defined by V_25Gy (the percentage thyroid volume that receives >25 Gy, not the absolute volume) ≤60%, V_35Gy  ≤ 55%, and V_45Gy  ≤ 45%. Patients whose thyroid DVHs satisfied these constraints had a lower prevalence of 2-year HT compared with the overall prevalence (13.2% vs 25.8%, P < .001). Another DVH was defined by V_25Gy  > 95%, V_35Gy  > 90%, and V_45Gy  > 75%, and patients whose thyroid DVHs satisfied with these constraints had a higher prevalence of 2-year HT than the overall incidence (36.0% vs 25.8%, P < .001).

CONCLUSION

We recommend V_25Gy  ≤ 60%, V_35Gy  ≤ 55%, and V_45Gy  ≤ 45% as the "stringent" DVH line, and V_25Gy  > 95%, V_35Gy  > 90%, and V_45Gy  > 75% as the "inhibition" DVH line, under the precondition of not compromising the target coverage. These findings could help in the design of individual treatment plans and, eventually, to lowering of HT prevalence.