Tumor factors associated with in‐field failure for nasopharyngeal carcinoma after intensity‐modulated radiotherapy

Long-term Outcomes Following Individualized Primary Tumor Clinical Target Volume Delineation Based on Stepwise Spread Patterns of Nasopharyngeal Carcinoma Treated With Intensity-Modulated Radiotherapy

PURPOSE

Our institution has developed an individualized elective primary tumor clinical target volume (CTVp) delineation protocol for nasopharyngeal carcinoma (NPC) based on stepwise tumor spread patterns in intensity modulated radiation therapy for over 10 years. Herein, we report the long-term efficacy and toxicities in patients with NPC treated under this protocol.

METHODS AND MATERIALS

A total of 7262 patients with histologically proven nonmetastatic NPC treated with intensity modulated radiation therapy following this individualized delineation protocol were retrospectively evaluated. Survival rates were estimated using the Kaplan-Meier method. Dose-volume histogram parameters for patients with local relapse were compared with those of propensity score-matched without local relapse. Dosimetric comparisons of our delineation protocol with the 2018 International Guideline (2018-IG) were conducted on representative early- and advanced-stage NPC cases.

RESULTS

The 5-year local relapse-free survival, regional relapse-free survival, distant metastasis-free survival, progression-free survival, and overall survival were 93.6%, 94.4%, 86.8%, 77.8%, and 86.0%, respectively. 92.3% of local relapses and 86.0% of regional relapses occurred within the 95% isodose lines and were considered in-field failures. No significant differences in dose-volume histogram parameters were observed between the local relapse group and the propensity score-matched nonrelapse group. Compared with the 2018-IG, our contouring protocol resulted in a 58.4% and 48.3% reduction in PTV70, and an 80.8% and 62.8% reduction in PTV60 for early and advanced-stage diseases, respectively. Late grade 3 toxicities included ototoxicity (1.8%), xerostomia (0.2%), dysphagia (0.2%), temporal lobe injury (0.2%), and trismus (0.1%).

CONCLUSIONS

Individualized elective CTVp delineation based on the stepwise spread patterns of nasopharyngeal carcinoma achieved excellent long-term outcomes and reduced the irradiated volumes at equivalent dose levels compared with the 2018-IG.

Recurrent Patterns in Patients With Nasopharyngeal Caricinoma and Risks Leading to Inaccurate Delineation in Marginal Failure in the Era of Intensity-Modulated Radiotherapy

OBJECTIVE

To investigate the failure patterns of recurrent nasopharyngeal carcinoma (NPC), especially to identify the relationship between the recurrent-prone anatomic structures and the tumor regression sites after the introduction of chemotherapy (IC).

METHOD

A cohort of 1121 non-metastatic patients with NPC was retrospectively enrolled. The pretreatment and recurrent images of each patient were registered to the planning CT. Tumor regression sites after IC (Vicr) overlapped with recurrent tumor (rGTV) were evaluated for the delineation accuracy and dose sufficiency in marginal failure patients.

RESULTS

A total of 126 (11.24%) experienced tumor recurrence. Re-evaluation of 12 patients with local marginal recurrence, their rGTV within Vicr predominantly located at choanae, sphenoidal sinus, and cavernous sinus. The regression sites did not receive the full 70 Gy but over half receiving with 60Gy.

CONCLUSION

Analysis from marginal failure that exempts tumor regression sites from GTV or an insufficient prescription dose of less than 70 Gy may contribute to marginal failure.

International Recommendations on Postoperative Management for Potentially Resectable Locally Recurrent Nasopharyngeal Carcinoma

Locally recurrent nasopharyngeal carcinoma (NPC) presents substantial challenges in clinical management. Although postoperative re-irradiation (re-RT) has been acknowledged as a potential treatment option, standardized guidelines and consensus regarding the use of re-RT in this context are lacking. This article provides a comprehensive review and summary of international recommendations on postoperative management for potentially resectable locally recurrent NPC, with a special focus on postoperative re-RT. A thorough search was conducted to identify relevant studies on postoperative re-RT for locally recurrent NPC. Controversial issues, including resectability criteria, margin assessment, indications for postoperative re-RT, and the optimal dose and method of re-RT, were addressed through a Delphi consensus process. The consensus recommendations emphasize the need for a clearer and broader definition of resectability, highlighting the importance of achieving clear surgical margins, preferably through an en bloc approach with frozen section margin assessment. Furthermore, these guidelines suggest considering re-RT for patients with positive or close margins. Optimal postoperative re-RT doses typically range around 60 Gy, and hyperfractionation has shown promise in reducing toxicity. These guidelines aim to assist clinicians in making evidence-based decisions and improving patient outcomes in the management of potentially resectable locally recurrent NPC. By addressing key areas of controversy and providing recommendations on resectability, margin assessment, and re-RT parameters, these guidelines serve as a valuable resource for clinical experts involved in the treatment of locally recurrent NPC.

Effect analysis of 847 nasopharyngeal carcinoma cases treated with intensity modulated radiation: Experience and suggestions

OBJECTIVES

To identify the failure patterns and prognostic factors of nonmetastatic nasopharyngeal carcinoma (NPC) in the intensity-modulated radiotherapy (IMRT) era.

METHODS

Data on 847 patients with newly diagnosed, non-disseminated NPC treated by IMRT between 2012 and 2016 were retrospectively reviewed. Survival outcome, failure patterns and prognosis factors were analyzed.

RESULTS

The 5-year local relapse-free survival, nodal relapse-free survival, distant metastasis-free survival, disease-free survival, and overall survival rates were 94.3%, 95.3%, 84.8%, 76.5% and 85.7%, respectively. The major local recurrence sites were the nasopharynx (91.5%, 43/47) and skull base (68.1%, 32/47); 39 patients had in-field failures, four had marginal failures, and four had out-field failures. Level IIb (62.2%, 23/37) was the most frequent regional recurrence site, followed by IIa (35.1%, 13/37) and retropharyngeal region (32.4%, 12/37); 35 cases had in-field failure alone, one had out-field failure alone, and one had both in- and out-field failure. TNM stage was the most significant factor for prognosis prediction. 402 (47.5%) patients had acute adverse events of grade 3 or 4; leukopenia (31.5%) and mucositis (26.7%) was the most common hematological and non-hematological event, respectively. Late complications were slight or moderate damages; xerostomia (647/847, 76.4%) and hearing impairment (422/847, 49.8%) remained the most troublesome.

CONCLUSION

NPC patients treated with IMRT obtained satisfactory survival outcomes. The key failure pattern was distant metastasis. The main pattern of local-regional failure was in-field failure. Screening high risk patients with distant metastases and optimizing radiotherapy targets should be studied.

New T staging recommendations for recurrent nasopharyngeal carcinoma

OBJECTIVE

The International Union for Cancer Control/American Joint Committee on Cancer (UICC/AJCC) rT staging is not clinically practical for recurrent nasopharyngeal carcinoma (rNPC). The aim of this study was to establish a new rT staging to guide the treatment of rNPC.

METHODS

We conducted a retrospective analysis of 175 patients diagnosed with rNPC between January 2012 and December 2020, using ROC curve analysis to evaluate its effectiveness.

RESULTS

We analyzed the overall survival (OS) and progression-free survival(PFS) of patients diagnosed with rNPC according to the 8th (UICC/AJCC) rT staging, and found that the overall survival of rT1 and rT2 patients (OS; 29.98% vs. 27.09%, p = 0.8059) and progression-free survival (PFS; 28.48% vs. 26.12%, p = 0.4045) had no significant difference. In rT1 and rT2 patients of this study, overall survival(OS; 30.44% vs. 24.91%, p = 0.0229) and progression-free survival(PFS 29.12% vs. 24.03%, p = 0.0459) had a significant difference. Smoking, family history, and time interval of initial recurrence were independent prognostic factors for OS and PFS.

CONCLUSION

The new rT staging of this study has a better predictive value for survival of rNPC patients than the 8th (UICC/AJCC) rT staging.

Efficacy of salvage surgery versus re-irradiation for isolated regional lymph node recurrence in patients with nasopharyngeal carcinoma

BACKGROUND

To compare the clinical characteristics and prognoses of patients with isolated regional lymph node recurrent nasopharyngeal carcinoma (irrNPC) who underwent surgery or re-irradiation treatment.

METHODS

We retrospectively reviewed 124 irrNPC patients who underwent initial radiotherapy between January 2010 and December 2020. The staging of regional lymph node recurrence was as follows: 75.8% for rN1, 14.5% for rN2, and 9.7% for rN3. Fifty-five patients underwent regional lymph node surgery (Surgery group), and sixty-nine patients received salvage radiotherapy with or without chemotherapy (Re-irradiation group). The survival rate was compared using Kaplan‒Meier analysis and evaluated by the log-rank test. Cox proportional hazard models were used to analyze prognostic factors.

RESULTS

The median follow-up time was 70 months, the 5-year overall survival (OS) was 74%, and the median survival time was 60.8 months. There were no significant differences in 5-year OS (75.6% vs. 72.4%, P = 0.973), regional recurrence-free survival (RRFS, 62.7% vs. 71.1%, P = 0.330) or distant metastasis-free survival (DMFS, 4.2% vs.78.7%, P = 0.677) between the Surgery group and Re-irradiation group. Multivariate analysis revealed age at recurrence, radiologic extra-nodal extension (rENE) status, and recurrent lymph node (rN) classification as independent prognostic factors for OS. The rENE status was an independent prognostic factor for DMFS. Subgroup analysis of the Surgery group revealed that the rN3 classification was an adverse prognostic factor for OS. Age at recurrence ≥ 50 years, GTV-N dose, and induction chemotherapy were found to be independent prognostic factors for OS, RRFS, and DMFS, respectively, in the Re-irradiation group.

CONCLUSIONS

For NPC patients with isolated regional lymph node recurrence after initial radiotherapy, those who underwent surgery had survival prognosis similar to those who underwent re-radiotherapy with or without chemotherapy. A prospective study is needed to validate these findings.

Embracing Personalized Strategies in Radiotherapy for Nasopharyngeal Carcinoma: Beyond the Conventional Bounds of Fields and Borders

Radiotherapy is the primary treatment modality for non-metastatic nasopharyngeal carcinoma (NPC) across all TN-stages. Locoregional control rates have been impressive even from the 2D radiotherapy (RT) era, except when the ability to deliver optimal dose coverage to the tumor is compromised. However, short- and long-term complications following head and neck RT are potentially debilitating, and thus, there has been much research investigating technological advances in RT delivery over the past decades, with the primary goal of limiting normal tissue damage. On this note, with a plateau in gains of therapeutic ratio by modern RT techniques, future advances have to be focused on individualization of RT, both in terms of dose prescription and the delineation of target volumes. In this review, we analyzed the guidelines and evidence related to contouring methods, and dose prescription for early and locoregionally advanced (LA-) NPC. Next, with the preference for induction chemotherapy (IC) in patients with LA-NPC, we assessed the evidence concerning radiotherapy adaptations guided by IC response, as well as functional imaging and contour changes during treatment. Finally, we discussed on RT individualization that is guided by EBV DNA assessment, and its importance in the era of combinatorial immune checkpoint blockade therapy with RT.

Nomograms incorporating primary tumor response at mid-radiotherapy to predict survival in locoregionally advanced nasopharyngeal carcinoma

BACKGROUND

A nomogram that incorporates tumor response at mid-radiotherapy (mid-RT) to predict the prognosis of locoregionally advanced nasopharyngeal carcinoma (LA-NPC) has not been established.

METHODS

This study retrospectively reviewed 583 patients with LA-NPC who underwent magnetic resonance imaging scans at mid-RT (the fourth week of RT) between 2015 and 2019.

RESULTS

Primary tumor (PT) response at mid-RT was found to predict disease-free survival (DFS) and overall survival (OS). Independent factors from multivariable analysis to predict DFS and OS were assembled into nomograms with (nomograms Amid-RT and Bmid-RT ) or without (nomograms Abaseline and Bbaseline ) PT response. Internal validation revealed good performance of these nomograms in discrimination: C-statistics = 0.761 for nomogram Amid-RT and 0.809 for nomogram Bmid-RT , which showed better discrimination performance than (C-statistics: 0.755) nomogram Abaseline and (C-statistics: 0.798) nomogram Bbaseline (Z-statistic = 2.476, p < 0.05; Z-statistic = 1.971, p < 0.05).

CONCLUSION

The nomograms based on PT response at mid-RT showed favorable predictive accuracy for DFS and OS in patients with LA-NPC.

Why subclinical involvement is prescribed the same high dose as gross tumor volume: A study on high-dose clinical target volume in intensity-modulated radiotherapy plan of nasopharyngeal carcinoma

BACKGROUND

Most nasopharyngeal carcinoma (NPC) protocols define primary gross tumor volume (GTVnx) plus a range from 2 to 5 mm as the high-dose clinical target volume (hd-CTV). However, in China, hd-CTV is defined as GTVnx plus 0 mm.

METHODS

A total of 40 patients with newly diagnosed nonmetastatic NPC (T1-T4 ten cases each) treated with IMRT were consecutively enrolled. Real and virtual treatment plans were designed according to the definitions of hd-CTV recommended by China and Radiation Therapy Oncology Group (RTOG), respectively.

RESULTS

The hd-CTV in China was significantly smaller than that of RTOG. Exposure doses to 5 mm subclinical involvement and OARs as well as NTCP in the China treatment plan were significantly lower than those of RTOG.

CONCLUSION

It could be recommended to divide the hd-CTV into GTV and subclinical target volume and to prescribe different doses for the GTV and subclinical involvement in the IMRT plan of NPC.

Prognostic generalization of multi-level CT-dose fusion dosiomics from primary tumor and lymph node in nasopharyngeal carcinoma

PURPOSE

To investigate the prognostic performance of multi-level computed tomography (CT)-dose fusion dosiomics at the image-, matrix-, and feature-levels from the gross tumor volume (GTV) at nasopharynx and the involved lymph node for nasopharyngeal carcinoma (NPC) patients.

METHODS

Two hundred and nineteen NPC patients (175 vs. 44 for training vs. internal validation) were used to train prediction model, and 32 NPC patients were used for external validation. We first extracted CT and dose information from intratumoral nasopharynx (GTV_nx) and lymph node (GTV_nd) regions. Then, the corresponding peritumoral regions (RING_3 mm and RING_5 mm) were also considered. Thus, the individual and combination of intratumoral and peritumoral regions were as follows: GTV_nx, GTV_nd, RING_3 mm_nx, RING_3 mm_nd, RING_5 mm_nx, RING_5 mm_nd, GTV_nxnd, RING_3 mm_nxnd, RING_5 mm_nxnd, GTV + RING_3 mm_nxnd, and GTV + RING_5 mm_nxnd. For each region, 11 models were built by combining five clinical parameters and 127 features from: (1) dose images alone; (2-7) fused dose and CT images via wavelet-based fusion using CT weights of 0.2, 0.4, 0.6, and 0.8, gradient transfer fusion, and guided-filtering-based fusion (GFF); (8) fused matrices (sumMat); (9-10) fused features derived via feature averaging (avgFea) and feature concatenation (conFea); and finally, (11) CT images alone. The concordance index (C-index) and Kaplan-Meier curves with log-rank test were used to assess model performance.

RESULTS

The fusion models' performance was better than single CT/dose model on both internal and external validation. Models that combined the information from both GTV_nx and GTV_nd regions outperformed the single region model. For internal validation, GTV + RING_3 mm_nxnd GFF model achieved the highest C-index both in recurrence-free survival (RFS) and metastasis-free survival (MFS) predictions (RFS: 0.822; MFS: 0.786). The highest C-index in external validation set was achieved by RING_3 mm_nxnd model (RFS: 0.762; MFS: 0.719). The GTV + RING_3 mm_nxnd GFF model is able to significantly separate patients into high-risk and low-risk groups compared to dose-only or CT-only models.

CONCLUSION

Fusion dosiomics model combining the primary tumor, the involved lymph node, and 3 mm peritumoral information outperformed single-modality models for different outcome predictions, which is helpful for clinical decision-making and the development of personalized treatment.

Prognostic value of the cervical lymph node necrosis ratio in nasopharyngeal carcinoma

PURPOSE

Whether cervical lymph node necrosis (CNN) is an independent adverse prognostic factor in nasopharyngeal carcinoma (NPC) has not been determined. In this study, the CNN ratio was graded quantitatively to explore the prognostic value in NPC.

PARTICIPANTS AND METHODS

We retrospectively reviewed a total of 648 pathologically confirmed as NPC. We outlined metastatic lymph nodes and necrotic area of lymph nodes slice by slice on the magneticresonanceimages (MRI) cross section, and calculated the corresponding CNN ratio.

RESULTS

The median CNN ratio (17.37 %) was taken as the cut-off point, 256 (39.51 %) patients were divided into CNN1 group (<17.37 %, n = 128) and CNN2 group (≥17.37 %, n = 128), 392 (60.49 %) patients without lymph nodes necrosis were CNN0. Among the CNN0, CNN1 and CNN2 groups, five-year overall survival (OS) was 82.4 %, 76.6 % and 71.1 %, locoregional recurrence-free survival (LRRFS) was 91.3 %, 91.1 % and 90.5 %, distant metastasis-free survival (DMFS) was 83.7 %, 78.5 % and 68.7 %, progression-free survival (PFS) was 78.3 %, 71.7 % and 61.6 % respectively. By multivariate analysis, CNN was an independent prognostic factor for OS (P = 0.003), DMFS (P = 0.019) and PFS (P = 0.007). More than 3 cycles of chemotherapy significantly increased OS (P = 0.024) and DMFS (P = 0.015) in the CNN1 group.

CONCLUSIONS

This study indicated that CNN is one of the factors with the negative prognosis of NPC. The CNN ratio might be used as one of the reference factors in the formulation of individualized treatment plan.