SPECT/CT-guided elective nodal irradiation for head and neck cancer is oncologically safe and less toxic: A potentially practice-changing approach

Imaging Modalities for Head and Neck Cancer: Present and Future

Several imaging modalities are utilized in the diagnosis, treatment, and surveillance of head and neck cancer. First-line imaging remains computed tomography (CT); however, MRI, PET with CT (PET/CT), and ultrasound are often used. In the last decade, several new imaging modalities have been developed that have the potential to improve early detection, modify treatment, decrease treatment morbidity, and augment surveillance. Among these, molecular imaging, lymph node mapping, and adjustments to endoscopic techniques are promising. The present review focuses on existing imaging, novel techniques, and the recent changes to imaging practices within the field.

A multi-institutional feasibility lead-in trial of lymphatic mapping with SPECT-CT for evaluating contralateral disease in lateralized oropharynx cancer using 99m-technetium sulfur colloid

BACKGROUND

Lymphatic mapping with SPECT-CT has been demonstrated to accurately define lymphatic drainage patterns in oropharyngeal cancer but there has yet to be a study demonstrating its feasibility across multiple institutions.

METHODS

Twelve adult patients with lateralized oropharyngeal carcinoma (T1-T3) who were planned for definitive or adjuvant radiotherapy without contralateral nodal disease underwent injection of 99-m technetium sulfur colloid followed by static planar lymphoscintigraphy to verify tracer migration, and SPECT-CT acquired at 30 ± 15 min (optional) and 3 h (±1 h) (mandatory time-point).

RESULTS

All 12 patients completed the study with 7/12 patients having the injections performed under local anesthetic and 5 patients requiring general anesthetic. There were no tracer migration failures and there were no serious adverse events or complications encountered. Four out of 12 patients (33%) showed contralateral drainage patterns.

CONCLUSIONS

Lymphatic mapping with SPECT-CT of lateralized oropharyngeal squamous cell carcinoma can be performed safely across multiple institutions.

Is bilateral radiotherapy necessary for patients with unilateral squamous cell carcinoma of unknown primary of the head and neck region?

Background and Purpose

Squamous cell carcinoma of unknown primary (SCC-CUP) of the head and neck region remains a clinical challenge, with uncertainty surrounding the necessity of contralateral irradiation of cervical lymphatic drainage in cases of unilateral involvement.

Materials and Methods

A retrospective study was conducted at the Department of Radiation Oncology, University Medical Center Mainz, on a cohort of 50 patients with unilateral SCC-CUP of the head and neck region treated between 2005 and 2019. 30 patients received bilateral and 20 received unilateral cervical radiotherapy. The majority (n = 38, 76 %) were treated with modern IMRT/ VMAT (Intensity-modulated Radiation Therapy/ Volumetric Modulated Arc Therapy) techniques.

Results

After a median follow-up of 64.5 months, locoregional recurrences occurred in 26 % of cases (n = 13/50), all of which were ipsilateral and predominantly within the volume of the previous irradiated CTV (clinical target volume) (85 %, n = 11/13). No patient treated unilaterally developed a contralateral recurrence in the neck. After 3 years, we observed 7 locoregional recurrences in the bilateral irradiated group (n = 7/30, 23 %), and 5 locoregional recurrences in the unilateral irradiated group (n = 5/20, 25 %). After 3 years, 12 patients had died in the bilateral irradiated group (n = 12/30, 40 %), and 7 in the unilateral irradiated group (n = 7/20, 35 %). 7 Patients showed distant metastases after 3 years in the bilateral irradiated group (n = 7/30, 23 %), and 2 in the unilateral irradiated group (n = 2/20, 10 %). Locoregional control (LRC) at 5 years was 66.2 % in the bilaterally irradiated group, and 70.0 % in the unilaterally irradiated group. Overall survival (OS) was 52.6 % (bilateral) and 64.0 % (unilateral). Distant metastasis-free survival (DMFS) was 74.7 % (bilateral) and 84.4 % (unilateral). No significant differences were observed in OS (p = 0.37), LRC (p = 0.91), and DMFS (p = 0.91) between the groups.Acute toxicity ≥ °2 accordingly CTCAE (Common Terminology Criteria of Adverse Events) was high with 97% while late toxicity ≥ °2 was moderate with 31%. There was no statistically significant difference between the group of unilateral and bilateral irradiated patients.

Conclusion

These data suggest that contralateral cervical irradiation may be of limited benefit in patients with SCC-CUP, as recurrences occured ipsilaterally, and predominantly within the area of prior irradiation. Unilateral irradiation seems to be adequate for carefully selected patients.

Personalized neck irradiation guided by sentinel lymph node biopsy in patients with squamous cell carcinoma of the oropharynx, larynx or hypopharynx with a clinically negative neck: (Chemo)radiotherapy to the PRIMary tumor only. Protocol of the PRIMO study

Background

Elective neck irradiation (ENI) is performed in head and neck cancer patients treated with definitive (chemo)radiotherapy. The aim is to eradicate nodal metastases that are not detectable by pretreatment imaging techniques. It is conceivable that personalized neck irradiation can be performed guided by the results of sentinel lymph node biopsy (SLNB). It is expected that ENI can be omitted to one or both sides of the neck in 9 out of 10 patients, resulting in less radiation side effects with better quality of life.

Methods/design

This is a multicenter randomized controlled trial aiming to compare safety and efficacy of treatment with SLNB guided neck irradiation versus standard bilateral ENI in 242 patients with cN0 squamous cell carcinoma of the oropharynx, larynx or hypopharynx for whom bilateral ENI is indicated. Patients randomized to the experimental-arm will undergo SLNB. Based on the histopathologic status of the SLNs, patients will receive no ENI (if all SLNs are negative), unilateral neck irradiation only (if a SLN is positive at one side of the neck) or bilateral neck irradiation (if SLNs are positive at both sides of the neck). Patients randomized to the control arm will not undergo SLNB but will receive standard bilateral ENI. The primary safety endpoint is the number of patients with recurrence in regional lymph nodes within 2 years after treatment. The primary efficacy endpoint is patient reported xerostomia-related quality of life at 6 months after treatment.

Discussion

If this trial demonstrates that the experimental treatment is non-inferior to the standard treatment in terms of regional recurrence and is superior in terms of xerostomia-related quality of life, this will become the new standard of care.

Detectability and intra-fraction motion of individual elective lymph nodes in head and neck cancer patients on the Magnetic Resonance Image guided linear accelerator

Background and purpose

Individual elective lymph node irradiation instead of elective neck irradiation is a new concept for head-and-neck cancer (HNC) patients developed for the Magnetic Resonance Image guided linear accelerator (MR-linac). To prepare this, the detectability, volume changes and intra-fraction motion of elective lymph nodes on the MR-linac was assessed.

Materials and methods

A total of 15 HNC patients underwent diagnostic pre-treatment MRI. Additionally, two MR-linac scans were obtained with a 10-minute time difference in the first week of radiation treatment. Elective lymph node contours inside lymph node levels (Ib-V) were segmented on the pre-treatment MRI and the MR-linac scans and compared on number and maximal transversal diameter. Intra-fraction motion of elective lymph nodes on the MR-linac was estimated using Center of Mass (COM) distances and incremental isotropic expansion of lymph node segmentations.

Results

Of all 679 detected lymph nodes on the pre-treatment MRI, eight lymph nodes were not detectable on the first MR-linac scan and 16 new lymph nodes were detected. Lymph node diameters between the pre-treatment MRI scan and the MR-linac scan varied from -0.19 to + 0.13 mm. COM distances varied from 1.2 to 1.7 mm and lymph node contours had to be expanded with 3 mm.

Conclusions

Nearly all elective lymph nodes were detectable on the 1.5T MR-linac scan with no major changes in target volumes compared to the pre-treatment MRI. Simulated intra-fraction motion during the MR-linac scans was smaller than the 5-mm margin that will be used in the first elective lymph node radiation treatment.

Survival and Swallowing Function after Primary Radiotherapy versus Transoral Robotic Surgery for Human Papillomavirus-Associated Oropharyngeal Squamous Cell Carcinoma

INTRODUCTION

The aim of this study was to investigate the impact of primary transoral robotic surgery (TORS) versus radiotherapy (RT) on progression-free survival (PFS), overall survival (OS), and 1-year swallowing function for patients with early-stage HPV-associated oropharyngeal squamous cell carcinoma (OPSCC).

METHODS

Patients with stage I-II (AJCC 8th Ed.) HPV-associated OPSCC treated with TORS followed by risk-adapted adjuvant therapy or (chemo)radiotherapy between 2014 and 2019 were identified. PFS, OS, and swallowing outcomes including gastrostomy tube (GT) use/dependence, and Functional Oral Intake Scale (FOIS) change over 1 year were compared.

RESULTS

One hundred sixty-seven patients were analyzed: 116 treated with TORS with or without adjuvant RT and 51 treated with RT (50 chemoRT). The RT group had more advanced tumor/nodal stage, higher comorbidity, and higher rates of concurrent chemotherapy. There were no differences in 3-year PFS (88% TORS vs. 75% RT) or OS (90% vs. 81%) between groups, which persisted after adjusting for stage, age, and comorbidity. GT use/dependence rates were higher in the RT group. Mean (SD) FOIS scores in the TORS group were 6.9 (0.4) at baseline and 6.4 (1.0) at 1 year, compared with 6.7 (0.6) and 5.6 (1.7) for the RT group. Only clinical nodal stage was found to be significantly associated with FOIS change from baseline to 1 year.

CONCLUSION

There were no differences in PFS or OS between patients treated with primary TORS or RT for early-stage HPV-associated OPSCC. Clinical N2 status is associated with FOIS change at 1 year and may be the major factor affecting long-term swallowing function, irrespective of primary treatment modality.

The Sentinel Lymph Node in Treatment Planning: A Narrative Review of Lymph-Flow-Guided Radiotherapy

The sentinel lymph node technique is minimally invasive and used routinely by surgeons, reducing the need for morbid extensive lymph node dissections, which is a significant advantage for cancer staging and treatment decisions. The sentinel lymph node could also help radiation oncologists to identify tumor drainage for each of their patients, leading to a more personalized radiotherapy, instead of a probabilistic irradiation based on delineation atlases. The aim is both to avoid recurrence in unexpected areas and to limit the volume of irradiated healthy tissues. The aim of our study is to evaluate the impact of sentinel lymph node mapping for radiation oncologists. This concept, relying on sentinel lymph node mapping for treatment planning, is known as lymph-flow-guided radiotherapy. We present an up-to-date narrative literature review showing the potential applications of the sentinel lymph node technique for radiotherapy, as well as the limits that need to be addressed before its routine usage.

Sentinel node-assisted neck dissection in advanced oral squamous cell carcinoma-A new protocol for staging and treatment

BACKGROUND

Sentinel lymph node biopsy (SLNB) is used to improve the staging of and guide treatment in patients with early-stage T1-T2 N0 oral squamous cell carcinoma (OSCC). The role of sentinel nodes (SNs) and the use of SN-technique in advanced OSCC (T3-T4 and/or N+) remain to be evaluated. This study investigates the nodal drainage and the rate of positive SNs (SNs+) in all stages of OSCC.

MATERIALS AND METHODS

In total, 85 patients with T1-T4 OSCC diagnosed 2019-2021 were included. We used a prolonged interval between peritumoral injection of radionuclide and SPECT-CT to include all SNs.

RESULTS

Patients with advanced OSCC presented a higher proportion of contralateral lymphatic drainage and a higher rate of SN+ compared to patients with early-stage disease. T3-T4 and N+ tumors presented a tendency for a higher rate of contralateral lymphatic drainage compared to T1-T2 and N0 tumors (p = 0.1). The prevalence of positive nodes (SNs+) was higher among patients with advanced disease, T3-T4 versus T1-T2 (p = 0.0398).

CONCLUSION

SN-assisted ND enables identification and removal of all SNs + and has the potential for more accurate staging and could possibly give prognostic advantages regarding regional recurrence for all OSCC patients, especially among those with advanced disease. The precise localization of the SNs + also suggests that a more individualized ND approach might be possible in the future even for patients with advanced OSCC.

Sentinel node identification in laryngeal and pharyngeal carcinoma after flexible endoscopy-guided tracer injection under topical anesthesia: A feasibility study

BACKGROUND

The aim of this study was to investigate the feasibility of flexible endoscopy-guided tracer injection for sentinel lymph node (SLN) identification in patients with laryngeal and pharyngeal carcinoma.

METHODS

Sixteen cT1-4N0-2M0 patients with laryngeal or pharyngeal carcinoma underwent intra- and peritumoral [^99m Tc]Tc-nanocolloid injections after topical anesthesia under endoscopic guidance. SPECT-CT scans were performed at two time points.

RESULTS

Tracer injection and visualization of SLNs was successful in 15/16 (94%) patients. Median number of tracer injections was 1 intratumoral and 3 peritumoral. The median duration of the endoscopic procedure including tracer injection after biopsy taking was 7 min (range 4-16 min). A total of 28 SLNs were identified which were all visualized on the early and late SPECT-CT. Most SLNs were visualized in neck levels II and III.

CONCLUSIONS

Flexible endoscopy-guided tracer injection for SLN identification is a feasible and fast procedure in laryngeal and pharyngeal carcinoma patients.

Raaijmakers C, Philippens ME. Individual elective lymph node irradiation for the reduction of complications in head and neck cancer patients (iNode): A phase-I feasibility trial protocol

Introduction

The long-term complication rate in head-and-neck squamous cell carcinoma (HNSCC) patients caused by radiotherapy (RT) can be decreased by restricting elective neck irradiation (ENI) from large adjacent lymph node levels to only individual elective lymph nodes. The primary objective of this study is to treat the first HNSCC patients with individual elective lymph node irradiation by means of a Magnetic Resonance-linac (MR-linac) in order to assess the feasibility.

Methods and analysis

In this phase I feasibility study, 20 patients will be included with histologically proven cT2-4N0-1M0 HNSCC originating from the oropharynx, hypopharynx or larynx, planned for treatment with primary radiotherapy and bilateral elective neck irradiation (ENI). Patients will be treated with 35 fractions in six weeks, according to the DAHANCA schedule. Individual lymph nodes inside the conventional lymph node levels will be categorized in low-risk, intermediate-risk and high-risk based on cytology, histology and imaging parameters. Low-risk and intermediate-risk lymph nodes will irradiated in 20 and 23 fractions respectively, with a fraction dose of 2 Gy (=40/46 Gy EQD2). The high-risk lymph nodes and the primary tumor will be irradiated in 35 fractions of 2 Gy (=70 Gy equivalent dose in 2 Gy fractions (EQD2)). To limit treatment burden, 20 fractions will be applied on the MR-linac. The last 15 fractions (sequential boost at the primary tumor, intermediate-risk and high-risk lymph nodes) will be applied on a conventional linear accelerator. The main study endpoint is the percentage of fractions that are successfully completed on the MR-linac.

Ethics and dissemination

With individual elective lymph node irradiation we expect less toxicity and a better quality of life for HNSCC patients. However, as the treatment time on the MR-linac will be longer (30-45 vs 15 min per fraction) we need to examine if patients can endure this new treatment concept.

High-Accuracy Nodal Staging of Head and Neck Cancer With USPIO-Enhanced MRI: A New Reading Algorithm Based on Node-to-Node Matched Histopathology

OBJECTIVES

Ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging (MRI) is a potential diagnostic tool for lymph node assessment in patients with head and neck cancer. Validation by radiologic-pathologic correlation is essential before the method is evaluated in clinical studies. In this study, MRI signal intensity patterns of lymph nodes are correlated to their histopathology to develop a new USPIO-enhanced MRI reading algorithm that can be used for nodal assessment in head and neck cancer patients.

MATERIALS AND METHODS

Ten head and neck cancer patients underwent in vivo USPIO-enhanced MRI before neck dissection. An ex vivo MRI of the neck dissection specimen was performed for precise coregistration of in vivo MRI with histopathology. Normal clinical histopathological workup was extended with meticulous matching of all lymph nodes regarded as potentially metastatic based on their in vivo MRI signal intensity pattern. On the basis of histopathology of resected nodes, in vivo MRI signal characteristics were defined separating benign from malignant lymph nodes.

RESULTS

Fifteen of 34 node-to-node correlated lymph nodes with remaining signal intensity on T2*-weighted MRI were histopathologically metastatic and 19 were benign. Radiological analysis revealed that metastatic lymph nodes showed equal or higher MRI signal intensity when compared with lipid tissue on T2*-weighted MGRE sequence (15/16 lymph nodes; 94%), whereas healthy lymph nodes showed lower (17/19 lymph nodes; 89%) or complete attenuation of signal intensity (273/279; 98%) when compared with lipid tissue on T2*-weighted MGRE. Histopathology of all resected specimens identified 392 lymph nodes. Six lymph nodes with (micro)metastases were missed with in vivo MRI. Whether these 6 lymph nodes were correlated to a nonmalignant lymph node on in vivo MRI or could not be detected at all is unclear.

CONCLUSIONS

We developed a new reading algorithm to differentiate benign from malignant lymph nodes in head and neck cancer patients on the basis of their appearance on high-resolution T2*-weighted USPIO-enhanced MRI. Next steps involve validation of our reading algorithm to further improve the accuracy of neck lymph node staging with USPIO-enhanced MRI in prospective clinical studies with larger number of patients.

Diagnostic test accuracy of sentinel lymph node biopsy in squamous cell carcinoma of the oropharynx, larynx, and hypopharynx: A systematic review and meta-analysis

The aim of this meta-analysis was to determine the diagnostic test accuracy of sentinel lymph node biopsy (SLNB) in patients with oropharyngeal, laryngeal, and hypopharyngeal squamous cell carcinoma (SCC). For this purpose, MEDLINE, EMBASE, and Web of Science were searched from inception to March 8, 2022. Included were studies evaluating diagnostic test accuracy of SLNB to identify cervical lymph node metastases with elective neck dissection or follow-up as reference. A bivariate generalized linear mixed model approach was used for the meta-analysis. Nineteen studies were eligible, evaluating 377 cases in total. The pooled estimates of sensitivity and negative predictive value were 0.93 (95% CI: 0.86-0.96) and 0.97 (95% CI: 0.94-0.98), respectively. The excellent accuracy of SLNB justifies a place in the diagnostic workup of patients with larynx and pharynx SCC. Randomized trials are required to demonstrate oncologic safety and benefits on treatment related morbidity and quality of life when omitting elective neck treatment based on SLNB.

Assessment of Occult Nodal Micrometastases to the Clinically Negative Contralateral Neck in Locally Advanced Supraglottic Squamous Cell Carcinoma

The aim of this study is  to study the incidence of occult nodal micrometastases (ONM) in the contralateral neck and compare it to the laterality of the primary tumor. Retrospective analysis of the medical records of patients with locally advanced supraglottic squamous cell carcinoma and Clinically negative contralateral neck (cN0-CLN) - who had concurrent total laryngectomy and bilateral neck dissection as their primary treatment at the Otolaryngology Department, Al Kas Al Ainy School of Medicine-Cairo University between 2015 and 2020 - was conducted. Patients were divided into 3 groups according to the extent of the primary tumor. 28 patients met the inclusion criteria. Patients with well-lateralized tumors were 14 (Group A), tumors abutting the midline were 4 (Group B) and tumors significantly involving the contralateral side were 14 (Group C). There was no statistically significant difference in age of patients among the three groups. Eleven patients had cervical lymphadenopathy in the final pathology reports. Seven patients had ONM, all of whom were among group C patients (7/14; 50%). The degree of tumor differentiation was not associated with the presence of ONM. Treatment of the cN0-CLN is justified in locally advance supraglottic carcinoma significantly crossing the midline. The total number of patients with ONM in the cN0-CLN exceeds the threshold for observation, however the authors could not recommend or refute the practice of routine prophylactic treatment of the cN0-CLN as none of the patients-in this study-with well-lateralized tumors or tumors just abutting the midline showed ONM.

Target Definition in MR-Guided Adaptive Radiotherapy for Head and Neck Cancer

In recent years, MRI-guided radiotherapy (MRgRT) has taken an increasingly important position in image-guided radiotherapy (IGRT). Magnetic resonance imaging (MRI) offers superior soft tissue contrast in anatomical imaging compared to computed tomography (CT), but also provides functional and dynamic information with selected sequences. Due to these benefits, in current clinical practice, MRI is already used for target delineation and response assessment in patients with head and neck squamous cell carcinoma (HNSCC). Because of the close proximity of target areas and radiosensitive organs at risk (OARs) during HNSCC treatment, MRgRT could provide a more accurate treatment in which OARs receive less radiation dose. With the introduction of several new radiotherapy techniques (i.e., adaptive MRgRT, proton therapy, adaptive cone beam computed tomography (CBCT) RT, (daily) adaptive radiotherapy ensures radiation dose is accurately delivered to the target areas. With the integration of a daily adaptive workflow, interfraction changes have become visible, which allows regular and fast adaptation of target areas. In proton therapy, adaptation is even more important in order to obtain high quality dosimetry, due to its susceptibility for density differences in relation to the range uncertainty of the protons. The question is which adaptations during radiotherapy treatment are oncology safe and at the same time provide better sparing of OARs. For an optimal use of all these new tools there is an urgent need for an update of the target definitions in case of adaptive treatment for HNSCC. This review will provide current state of evidence regarding adaptive target definition using MR during radiotherapy for HNSCC. Additionally, future perspectives for adaptive MR-guided radiotherapy will be discussed.

Elective upper-neck versus whole-neck irradiation of the uninvolved neck in patients with nasopharyngeal carcinoma: an open-label, non-inferiority, multicentre, randomised phase 3 trial

BACKGROUND

The aim of this trial was to address whether elective ipsilateral upper-neck irradiation (UNI) sparing the uninvolved lower neck provides similar regional relapse-free survival compared with standard whole-neck irradiation (WNI) in patients with nasopharyngeal carcinoma.

METHODS

This open-label, non-inferiority, randomised, controlled, phase 3 trial was done at three Chinese medical centres. Patients aged 18-65 years with untreated, non-keratinising, non-distant metastatic (M0) nasopharyngeal carcinoma; with N0-N1 disease (according to International Union Against Cancer-American Joint Committee on Cancer TNM classification, seventh edition); and a Karnofsky performance status score of 70 or higher were randomly assigned (1:1) to receive elective UNI or WNI of the uninvolved neck. Total radiation doses of 70 Gy (for the primary tumour volume and the enlarged retropharyngeal nodes), 66-70 Gy (for the involved cervical lymph nodes), 60-62 Gy (for the high-risk target volume), and 54-56 Gy (for the low-risk target volume) were administered in 30-33 fractions, five fractions per week. Patients with stage II-IVA disease were recommended to receive combined intravenous cisplatin-based chemotherapy (either induction chemotherapy followed by concurrent chemoradiotherapy or concurrent chemoradiotherapy alone). Randomisation was done centrally by the Clinical Trials Centre of Sun Yat-sen University Cancer Centre by means of a computer-generated random number code with a block size of four. Patients were stratified according to treatment centre and nodal status. Investigators and patients were not masked to treatment allocation. The primary endpoint was regional relapse-free survival in the intention-to-treat population. Non-inferiority was indicated if the upper limit of the 95% CI of the difference in 3-year regional relapse-free survival between the UNI and WNI groups was within 8%. Adverse events were analysed in the safety population (defined as all patients who commenced the randomly assigned treatment). This study is registered with ClinicalTrials.gov, NCT02642107, and is closed.

FINDINGS

Between Jan 22, 2016, and May 23, 2018, 446 patients from 469 screened were randomly assigned to receive UNI (n=224) or WNI (n=222). Median follow-up was 53 months (IQR 46-59). 3-year regional relapse-free survival was similar in the UNI and WNI groups (97·7% [95% CI 95·7-99·7] in the UNI group vs 96·3% [93·8-98·8] in the WNI group; difference -1·4% [95% CI -4·6 to 1·8]; p_{non-inferiority}<0·0001). Although acute radiation-related toxic effects were similar between the groups, the incidence of late toxicity was lower in the UNI group than in the WNI group, including any-grade hypothyroidism (66 [30%] of 222 patients vs 87 [39%] of 221), skin toxicity (32 [14%] vs 55 [25%]), dysphagia (38 [17%] vs 71 [32%]), and neck tissue damage (50 [23%] vs 88 [40%]). No patients died during treatment. After treatment, one patient in the WNI group died from a non-cancer-related cause (dermatomyositis).

INTERPRETATION

Elective UNI of the uninvolved neck provides similar regional control and results in less radiation toxicity compared with standard WNI in patients with N0-N1 nasopharyngeal carcinoma.

FUNDING

Sun Yat-sen University Clinical Research 5010 Program, the Natural Science Foundation of Guangdong Province, and the Overseas Expertise Introduction Project for Discipline Innovation.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Single vocal cord irradiation for early-stage glottic cancer: Excellent local control and favorable toxicity profile

OBJECTIVE

To validate the earlier reported promising oncologic outcomes and favorable toxicity profile following single vocal cord irradiation (SVCI) in an expanded cohort of patients with early-stage glottic cancer treated at our institute with longer follow-up time.

MATERIALS AND METHODS

Between February 2011 and January 2020, 111 consecutive patients with early-stage glottic cancer were treated with SVCI to the whole involved vocal cord (58.08 Gy, given in 16 fractions of 3.63 Gy). Setup verification was done using cone-beam CT, prior to each fraction. The endpoints were local control (LC), overall survival (OS), grade ≥ 3 toxicity and voice quality assessment using voice-handicap index (VHI) questionnaires.

RESULTS

Median follow-up was 41 months (range; 8-84). Two patients developed in-field local failure (LF). The 3- and 5-year LC rates were 99.1% and 97.1%, respectively. As both patients with LF were successfully salvaged with total laryngectomy, the 5-year ultimate LC-rates was 99%. The 5-years OS was 80.6%. All patients finished treatment without any interruption. No patients developed acute grade ≥ 3 toxicity. Late grade 3 toxicity was reported in 7 patients (6.5%) out of 108 patients evaluable for late toxicity; 2 because of severe hoarseness and 5 because of laryngeal radionecrosis (4.5%). The 5-years laryngectomy-free survival was 98.1%. The VHI-scores improved over time, only 22% of patients had VHI > 30 at 3-years post-radiotherapy, compared to 38% at baseline.

CONCLUSIONS

Local control rate and laryngectomy-free survival of SVCI are excellent with favorable toxicity profile and good VHI-score. These results validate our early results.

The dosimetric and clinical advantages of the GTV-CTV-PTV margins reduction by 6 mm in head and neck squamous cell carcinoma: Significant acute and late toxicity reduction

PURPOSE

We aim to identify the dosimetric and clinical impact of reducing the total GTV-CTV-PTV margins in head-and-neck squamous cell carcinoma (HNSCC) treated with definitive (chemo)radiation.

MATERIALS AND METHODS

The acute and late toxicity and outcomes of 155 consecutive patients treated between February 2017 and March 2019 with GTV-CTV-PTV margins of 9 mm were compared to those of 155 consecutive patients treated with total margin of 15 mm margin, before April 2015. All patients were treated with VMAT with daily-image guidance using CBCT.

RESULTS

Reducing the GTV-CTV-PTV by 6 mm resulted in significant reduction of total irradiated volume (PTV-total) by a median of 28.1% and significant reduction of doses to all salivary glands (largest reduction ipsilateral parotid gland; median -9.6 Gy) and constrictor muscle (-6.1 Gy) with subsequent reduction of the incidence of overall acute grade 3 toxicity (47.7% for 9 mm and 66.5% for 15 mm groups, p = 0.001), grade 3 mucositis (18.1% vs. 35.5%, p < 0.001) and feeding tube-dependency at the end of treatment (24.5% vs. 40%, p = 0.005). The incidence of late grade ≥ 2 xerostomia and dysphagia were also significantly lower in the 9 mm group (31.7% vs. 58.6% p < 0.001, and 15.4% vs. 26.7%, p = 0.04). The 2-year rates of loco-regional control, disease-free and overall survival were 78.8% vs.75.8%, 70.9% vs. 64.4%, and 83.8% vs. 67.6%, (p > 0.05, all).

CONCLUSION

Reduction of the total GTV-CTV-PTV margins from 15 to 9 mm in HNSCC significantly reduced the irradiated volumes and the dose to salivary glands and constrictor muscle with significant reduction of radiation-related toxicity. The loco-regional control rates of both groups were comparable.

Reducing target volume in definitive radiotherapy for human papillomavirus-associated tonsil cancer

BACKGROUND

To evaluate the efficacy and safety of reducing target volume in definitive radiotherapy for HPV-associated tonsil cancer.

METHODS

A single-institution cohort of 90 patients with human papillomavirus (HPV)-associated tonsil cancer who received definitive radiotherapy with a 5-mm expansion from the gross tumor volume to clinical target volume between 2008 and 2019 were included. The overlapping volume of initial planning target volume and the recurrent tumor was calculated and categorized as one of three failure types: in-field: ≥95%; marginal-field: 50%-94%; and out-field: <50%.

RESULTS

With a median follow-up of 59.4 months, the 3-year and 5-year local control rates were 94.4% and 92.8%, respectively. A total of seven local failures were identified, of which 4 (4.4%) were in-field, 2 (2.2%) were marginal-field, and 1 (1.1%) was out-field. Grade 3 acute and late toxicities developed in 30 (33.3%) and 5 (5.6%) patients, respectively.

CONCLUSIONS

Reducing target volume could be an alternative option for selected patients with HPV-associated tonsil cancer.

Single photon emission computed tomography-computed tomography visualization of sentinel lymph nodes for lymph flow guided nodal irradiation in oral tongue cancer

PURPOSE

To evaluate correlation of single photon emission computed tomography-computed tomography (SPECT-CT) data on lymph flow (LF) from oral tongue cancer (OC) and the topography of lymph nodes (LN) metastases; to determine the clinical value of lymph flow guided radiotherapy (LFGRT).

MATERIALS AND METHODS

SPECT-CT visualization of LF from the OC lesions was performed after peritumoral injection of 99mTc-phytate in 26 primary patients with clinical stage cT1-2N0M0 disease. We determined the individual drainage (unilateral/bilateral) from the tumor, and localization of sentinel LNs according to the neck levels. Metastases in LNs were verified with histology and a 2-year follow-up.

RESULTS

SPECT-CT detected bilateral LF in 10 (38.5%) of 26 patients; in 16 (61.5%) cases the drainage was unilateral. Histology revealed LNs metastases in three cases; regional recurrences were diagnosed in other four patients. In all seven observations metastases were located at the same site and level as the sentinel LNs. In eight (30.8%) of 26 patients sentinel LNs were visualized unilaterally at levels Ib-IIa; in five cases, unilaterally at levels I-IIa-III. In these patients, LFGRT demonstrated 59%-70% reduction of irradiated volume, and 26%-42% and 51%-70% decrease of the mean dose to the spinal cord and the contralateral parotid gland. In patients with a bilateral drainage the reduction of doses absorbed by the spinal cord and contralateral parotid gland was 19% and 6%, respectively.

CONCLUSION

Localization of sentinel LNs determined by SPECT-CT corresponds to the localization of metastatic LNs in terms of side and levels.

Reduction of GTV to high-risk CTV radiation margin in head and neck squamous cell carcinoma significantly reduced acute and late radiation-related toxicity with comparable outcomes

BACKGROUND AND PURPOSE

We aim to retrospectively investigate whether reducing GTV to high-risk CTV margin will significantly reduce acute and late toxicity without jeopardizing outcome in head-and-neck squamous cell carcinoma (HNSCC) treated with definitive (chemo)radiation.

MATERIALS AND METHODS

Between April 2015 and April 2019, 155 consecutive patients were treated with GTV to high-risk CTV margin of 10 mm and subsequently another 155 patients with 6 mm margin. The CTV-PTV margin was 3 mm for both groups. All patients were treated with volumetric-modulated arc therapy with daily image-guidance using cone-beam CT. End points of the study were acute and late toxicity and oncologic outcomes.

RESULTS

Overall acute grade 3 toxicity was significantly lower in 6 mm, compared to 10 mm group (48% vs. 67%, respectively, p < 0.01). The same was true for acute grade 3 mucositis (18% vs. 34%, p < 0.01) and grade ≥ 2 dysphagia (67% vs. 85%, p < 0.01). Also feeding tube-dependency at the end of treatment (25% vs. 37%, p = 0.02), at 3 months (12% and 25%, p < 0.01), and at 6 months (6% and 15%, p = 0.01) was significantly less in 6 mm group. The incidence of late grade 2 xerostomia was also significantly lower in the 6 mm group (32% vs. 50%, p < 0.01). The 2-year rates of loco-regional control, disease-free and overall survival were 78.7% vs. 73.1%, 70.6% vs. 61.4%, and 83.2% vs. 74.4% (p > 0.05, all).

CONCLUSION

The first study reporting on reduction of GTV to high-risk CTV margin from 10 to 6 mm showed significant reduction of the incidence and severity of radiation-related toxicity without reducing local-regional control and survival.

Unilateral versus bilateral nodal irradiation: Current evidence in the treatment of squamous cell carcinoma of the head and neck

Cancers of the head and neck region often present with nodal involvement. There is a long-standing convention within the community of head and neck radiation oncology to irradiate both sides of the neck electively in almost all cases to include both macroscopic and microscopic disease extension (so called elective nodal volume). International guidelines for the selection and delineation of the elective lymph nodes were published in the early 2000s and were updated recently. However, diagnostic imaging techniques have improved the accuracy and reliability of nodal staging and as a result, small metastases that used to remain undetected and were thus in the past included in the elective nodal volume, will now be included in high-dose volumes. Furthermore, the elective nodal areas are situated close to the parotid glands, the submandibular glands and the swallowing muscles. Therefore, irradiation of a smaller, more selected volume of the elective nodes could reduce treatment-related toxicity. Several researchers consider the current bilateral elective neck irradiation strategies an overtreatment and show growing interest in a unilateral nodal irradiation in selected patients. The aim of this article is to give an overview of the current evidence about the indications and benefits of unilateral nodal irradiation and the use of SPECT/CT-guided nodal irradiation in squamous cell carcinomas of the head and neck.

Comparing unilateral vs. bilateral neck management in lateralized oropharyngeal cancer between surgical and radiation oncologists: An international practice pattern survey

BACKGROUND

Management of the neck in oropharyngeal carcinoma varies due to a lack of clarity of patterns of lymphatic drainage and concern of failure in the contralateral neck. With recent advances in transoral surgical techniques, surgical management has become increasingly prevalent as the primary treatment modality. We compare international practice patterns between surgical and radiation oncologists.

METHODS

A survey of neck management practice patterns was developed and pilot tested by 6 experts. The survey comprised items eliciting the nature of clinical practice, as well as patterns of neck management depending on extent of nodal disease and location and extent of primary site disease. Proportions of surgical and radiation oncologists treating the neck bilaterally were compared using the chi-squared statistic.

RESULTS

Two-hundred and twenty-two responses were received from 172 surgical oncologists, 44 radiation oncologists, 3 medical oncologists, and 3 non-oncologists from 32 different countries. For tongue base cancers within 1 cm of midline (67% vs. 100%, p < 0.001), and for tonsil cancers with extension to the medial 1/3 of the soft palate (65% vs. 100%, p < 0.001) or tongue base (77% vs. 100%, p < 0.001), surgical oncologists were less likely to treat the neck bilaterally. For isolated tonsil fossa cancers with no nodal disease, both surgical and radiation oncologists were similarly likely to treat unilaterally (99% vs. 97%, p = NS). However, with increasing nodal burden, radiation oncologists were more likely to treat bilaterally for scenarios with a single node < 3 cm (15% vs. 2%, p < 0.001), a single node with extranodal extension (41% vs. 18%, p < 0.001), multiple positive nodes (55% vs. 23% p < 0.001), and node(s) > 6 cm (86% vs. 33%, p < 0.001). For tumors with midline extension, even with a negative PET in the contralateral neck, the majority of surgical and radiation oncologists would still treat the neck bilaterally (53% and 84% respectively).

CONCLUSIONS

The present study demonstrates significant practice pattern variability for management of the neck in patients with lateralized oropharyngeal carcinoma. Surgical oncologists are less likely to treat the neck bilaterally, regardless of tumor location or nodal burden. Even in the absence of disease in the contralateral neck on imaging, them majority of practitioners are likely to treat bilaterally when the disease approaches midline.

What is the role of sentinel lymph node biopsy in the management of oral cancer in 2020?

Approximately 70–80% of patients with cT1-2N0 oral squamous cell carcinoma (OSCC) ultimately prove to have no cancer in the cervical lymphatics on final pathology after selective neck dissection. As a result, sentinel lymph node biopsy (SLNB) has been adopted during the last decade as a diagnostic staging method to intelligently identify patients who would benefit from formal selective lymphadenectomy or neck irradiation. While not yet universally accepted, SLNB is now incorporated in many national guidelines. SLNB offers a less invasive alternative to elective neck dissection (END), and has some advantages and disadvantages. SLNB can assess the individual drainage pattern and, with step serial sectioning and immunohistochemistry (IHC), can enable the accurate detection of micrometastases and isolated tumor cells (ITCs). Staging of the neck is improved relative to END with routine histopathological examination. The improvements in staging are particularly notable for the contralateral neck and the pretreated neck. However, for floor of mouth (FOM) tumors, occult metastases are frequently missed by SLNB due to the proximity of activity from the primary site to the lymphatics (the shine through phenomenon). For FOM cancers, it is advised to perform either elective neck dissection or superselective neck dissection of the preglandular triangle of level I. New tracers and techniques under development may improve the diagnostic accuracy of SLNB for early-stage OSCC, particularly for FOM tumors. Treatment of the neck (either neck dissection or radiotherapy), although limited to levels I–IV, remains mandatory for any positive category of metastasis (macrometastasis, micrometastasis, or ITCs). Recently, the updated EANM practical guidelines for SLN localization in OSCC and the surgical consensus guidelines on SLNB in patients with OSCC were published. In this review, the current evidence and results of SLNB in early OSCC are presented.

Healthcare resource utilization following unilateral versus bilateral radiation therapy for oropharyngeal carcinoma

PURPOSE

To describe differences in healthcare resource utilization between patients treated with bilateral vs. unilateral neck radiation therapy (RT) for lateralized oropharyngeal cancer.

METHODS

A propensity score matching strategy was used to identify two otherwise clinically similar cohorts of tonsillar cancer patients treated with either bilateral or unilateral neck RT. Cohorts were matched based on similar propensity scores for age, sex, ECOG performance status, pack-year smoking history, cT-category, cN-category, HPV-status, and use of concurrent chemotherapy. Short term (from start of RT to 3 months following end of RT) resource utilization included: 1) outpatient supportive care visits, 2) hospital admission, and 3) interventions (feeding tube insertion and outpatient intravenous hydration). Long-term resource utilization included feeding tube dependency at 1-year.

RESULTS

Among 559 patients with tonsillar cancer treated between 2004-2017, propensity score matching identified a unilateral neck RT cohort (n = 81) and bilateral neck RT cohort (n = 81) with similar clinical and treatment characteristics. Bilateral neck RT was associated with a higher likelihood of hospitalization (33% vs 12%, p < 0.01), outpatient IV hydration (33% vs 17%, p = 0.03), and feeding tube insertion (33% vs 10%, p < 0.001); a greater number of total days of hospitalization (110 vs 47 days, p < 0.01) and outpatient IV hydration (135 vs 72 days, p = 0.02); and higher total number of supportive clinic visits (1226 vs 1053 days, p = 0.04). In the long-term, bilateral RT was associated with higher rate of feeding tube dependency at 1-year (7% vs 0%, p < 0.001).

CONCLUSION

Bilateral RT for tonsillar cancer resulted in significant increase in health resource utilization.

New Developments in Imaging for Sentinel Lymph Node Biopsy in Early-Stage Oral Cavity Squamous Cell Carcinoma

Sentinel lymph node biopsy (SLNB) is a diagnostic staging procedure that aims to identify the first draining lymph node(s) from the primary tumor, the sentinel lymph nodes (SLN), as their histopathological status reflects the histopathological status of the rest of the nodal basin. The routine SLNB procedure consists of peritumoral injections with a technetium-99m [^99mTc]-labelled radiotracer followed by lymphoscintigraphy and SPECT-CT imaging. Based on these imaging results, the identified SLNs are marked for surgical extirpation and are subjected to histopathological assessment. The routine SLNB procedure has proven to reliably stage the clinically negative neck in early-stage oral squamous cell carcinoma (OSCC). However, an infamous limitation arises in situations where SLNs are located in close vicinity of the tracer injection site. In these cases, the hotspot of the injection site can hide adjacent SLNs and hamper the discrimination between tracer injection site and SLNs (shine-through phenomenon). Therefore, technical developments are needed to bring the diagnostic accuracy of SLNB for early-stage OSCC to a higher level. This review evaluates novel SLNB imaging techniques for early-stage OSCC: MR lymphography, CT lymphography, PET lymphoscintigraphy and contrast-enhanced lymphosonography. Furthermore, their reported diagnostic accuracy is described and their relative merits, disadvantages and potential applications are outlined.

Deep learning for elective neck delineation: More consistent and time efficient

BACKGROUND/PURPOSE

Delineation of the lymph node levels of the neck for irradiation of the elective clinical target volume in head and neck cancer (HNC) patients is time consuming and prone to interobserver variability (IOV), although international consensus guidelines exist. The aim of this study was to develop and validate a 3D convolutional neural network (CNN) for semi-automated delineation of all nodal neck levels, focussing on delineation accuracy, efficiency and consistency compared to manual delineation.

MATERIAL/METHODS

The CNN was trained on a clinical dataset of 69 HNC patients. For validation, 17 lymph node levels were manually delineated in 16 new patients by two observers, independently, using international consensus guidelines. Automated delineations were generated by applying the CNN and were subsequently corrected by both observers separately as needed for clinical acceptance. Both delineations were performed two weeks apart and blinded to each other. IOV was quantified using Dice similarity coefficient (DSC), mean surface distance (MSD) and Hausdorff distance (HD). To assess automated delineation accuracy, agreement between automated and corrected delineations were evaluated using the same measures. To assess efficiency, the time taken for manual and corrected delineations were compared. In a second step, only the clinically relevant neck levels were selected and delineated, once again manually and by applying and correcting the network.

RESULTS

When all lymph node levels were delineated, time taken for correcting automated delineations compared to manual delineations was significantly shorter for both observers (mean: 35 vs 52 min, p < 10^-5). Based on DSC, automated delineation agreed best with corrected delineation for lymph node levels Ib, II-IVa, VIa, VIb, VIIa, VIIb (DSC >85%). Manual corrections necessary for clinical acceptance were 1.4 mm MSD on average and were especially low (<1mm) for levels II-IVa, VIa, VIIa and VIIb. IOV was significantly smaller with automated compared to manual delineations (MSD: 1.4 mm vs 2.5 mm, p < 10^-11). When delineating only the clinically relevant neck levels, the correction time was also significantly shorter (mean: 8 vs 15 min, p < 10^-5). Based on DSC, automated delineation agreed very well with corrected delineation (DSC > 87%). Manual corrections necessary for clinical acceptance were 1.3 mm MSD on average. IOV was significantly smaller with automated compared to manual delineations (MSD: 0.8 mm vs 2.3 mm, p < 10^-3).

CONCLUSION

The CNN developed for automated delineation of the elective lymph node levels in the neck in HNC was shown to be more efficient and consistent compared to manual delineation, which justifies its implementation in clinical practice.

Short-term and long-term unstimulated saliva flow following unilateral vs bilateral radiotherapy for oropharyngeal carcinoma

BACKGROUND

We aimed to compare unstimulated saliva flow using 3-minute modified Schirmer test (MST) following bilateral vs unilateral radiotherapy (RT) in oropharyngeal carcinoma (OPC).

METHODS

We reviewed OPC patients treated with definitive intensity-modulated radiation therapy (IMRT) between 2011 and 2017. MST was measured at baseline, 1-/6-/12-/24-month post-RT. MST values were compared between bilateral-RT vs unilateral-RT groups. Multivariable logistic regression analysis (MVA) identified predictors of hyposalivation (MST < 25 mm).

RESULTS

Total 498 bilateral-RT and 36 unilateral-RT patients were eligible. The MST values at 1-/6-/12-/24-month post-RT were all significantly reduced from baseline for the entire cohort. Baseline unilateral-RT and bilateral-RT MST values (in mm) were similar (P = .2), but much higher for unilateral-RT 1-month (mean: 19.1 vs 13.0, P = .03), 6-month (20.5 vs 9.3, P < .001), 12-month (20.1 vs 11.9, P < .01), and 24-month post-RT (22.2 vs 13.9, P = .04). MVA confirmed that unilateral RT reduced the likelihood of hyposalivation vs bilateral RT (OR 2.36, P = .006).

CONCLUSION

Unilateral RT reduces unstimulated salivary flow in OPC patients.

Death unrelated to cancer and death from aspiration pneumonia after definitive radiotherapy for head and neck cancer

BACKGROUND AND PURPOSE

The incidence of hypopharyngeal and supraglottic cancer (HSC) is high in Japan. This study aimed to retrospectively identify risk factors for death unrelated to cancer and death from aspiration pneumonia after definitive radiotherapy (RT) for HSC.

MATERIALS AND METHODS

Overall, 391 patients who began definitive RT for HSC between 2006 and 2014 were identified from the Osaka International Cancer Institute electronic database. Among 391 patients, 33 had a history of surgery for esophageal cancer (EC) and 19 received simultaneous RT for synchronous EC. The cause of death was divided into 3 main categories: "cancer under study," "other malignancy," and "unrelated to cancer." Cox proportional hazard model was used to estimate the hazard ratio (HR).

RESULTS

The median follow-up for survivors was 8 (range 3.6-14.1) years. At the last follow-up, 202 patients died. Death from "cancer under study," "other malignancy," and "unrelated to cancer" occurred in 92 (45.5%), 55 (27.2%), and 55 (27.2%) patients, respectively. Twelve patients died from aspiration pneumonia. In multivariate analysis for death unrelated to cancer and death from aspiration pneumonia, history of surgery for EC (HR: 3.87, p < 0.001; HR: 6.84, p = 0.007, respectively) and simultaneous RT for synchronous EC (HR: 3.74, p = 0.006; HR: 16.37, p < 0.001, respectively) were significant risk factors.

CONCLUSION

The laryngeal preservation approach by RT for HSC patients with a history of surgery for EC and simultaneous RT for synchronous EC should be used with caution.

Lymphoscintigraphy for Sentinel Node Mapping in Head and Neck Cancer

The aim of this comprehensive review is to describe and analyze the role of the sentinel node mapping in head and neck cancers. For this purpose, head and neck neoplasms have been categorized in cutaneous malignancies and neoplasms of the upper aerodigestive tract. A concise description of lymphatic drainage will be the "prelude" for each section, as well as the description of the injection techniques, when specific. Concisely, the attention has been focused on detection rate of the sentinel node by lymphoscintigraphy for each cancer, and for those patients in which the sentinel lymph node has been identified, true-positives rates, false-negative rates, and overall accuracy has been pointed out. Overall, in cutaneous neoplasms of the head and neck, the detection rate is higher than 90%, however the false-negative rate is still an issue, in particular in melanoma, inducing the need for newer developments. In fact, new tracers and techniques are already available, while prospective multicenter trials exploring the outcome impact are needed in the near future. For the upper aerodigestive tract and in particular oral cavity and oropharynx, sentinel lymph node identification by lymphoscintigraphy allows avoiding unnecessary neck dissection and/or node irradiation. Even in this case, the main limit remains the risk of false-negative rates. While, for patients affected by laryngeal and hypopharyngeal cancers the data seem very limited and, although the feasibility has been demonstrated, performances of this lymphoscintigraphy still need to be confirmed by multicenter studies.

Emerging Concepts and Novel Strategies in Radiation Therapy for Laryngeal Cancer Management

Laryngeal squamous cell carcinoma is the second most common head and neck cancer. Its pathogenesis is strongly associated with smoking. The management of this disease is challenging and mandates multidisciplinary care. Currently, accepted treatment modalities include surgery, radiation therapy, and chemotherapy—all focused on improving survival while preserving organ function. Despite changes in smoking patterns resulting in a declining incidence of laryngeal cancer, the overall outcomes for this disease have not improved in the recent past, likely due to changes in treatment patterns and treatment-related toxicities. Here, we review emerging concepts and novel strategies in the use of radiation therapy in the management of laryngeal squamous cell carcinoma that could improve the relationship between tumor control and normal tissue damage (therapeutic ratio).