The accuracy of target delineation in laryngeal and hypopharyngeal cancer

Oncological outcome of vocal cord-only radiotherapy for cT1-T2 glottic laryngeal squamous cell carcinoma

PURPOSE

Early-stage glottic cancer can be treated with radiotherapy only. Modern radiotherapy solutions allow for individualized dose distributions, hypofractionation and sparing of organs at risk. The target volume used to be the entire voice box. This series describe the oncological outcome and toxicity of individualized vocal cord-only hypofractionated radiotherapy for early stage (cT1a-T2 N0).

METHODS

Retrospective cohort study with patients treated in a single center between 2014 and 2020.

RESULTS

A total of 93 patients were included. Local control rate was 100% for cT1a, 97% for cT1b and 77% for cT2. Risk factor for local recurrence was smoking during radiotherapy. Laryngectomy-free survival was 90% at 5 years. Grade III or higher late toxicity was 3.7%.

CONCLUSION

Vocal cord-only hypofractionated radiotherapy appears to be oncologically safe in early-stage glottic cancer. Modern, image-guided radiotherapy led to comparable results as historical series with very limited late toxicity.

Tumor volume definitions in head and neck squamous cell carcinoma - Comparing PET/MRI and histopathology

BACKGROUND AND PURPOSE

In cancer treatment precise definition of the tumor volume is essential, but despite development in imaging modalities, this remains a challenge. Here, pathological tumor volumes from the surgical specimens were obtained and compared to tumor volumes defined from modern PET/MRI hybrid imaging. The purpose is to evaluate mismatch between the volumes defined from imaging and pathology was estimated and potential clinical impact.

METHODS AND MATERIALS

Twenty-five patients with head and neck squamous cell carcinoma were scanned on an integrated PET/MRI system prior to surgery. Three gross tumor volumes (GTVs) from the primary tumor site were delineated defined from MRI (GTV_MRI), PET (GTV_PET) and one by utilizing both anatomical images and clinical information (GTV_ONCO). Twenty-five primary tumor specimens were extracted en bloc, scanned with PET/MRI and co-registered to the patient images. Each specimen was sectioned in blocks, sliced and stained with haematoxylin and eosin. All slices were digitalized and tumor delineated by a head and neck pathologist. The pathological tumor areas in all slices were interpolated yielding a pathological 3D tumor volume (GTV_PATO). GTV_PATOwas compared with the imaging GTV's and potential mismatch was estimated.

RESULTS

Thirteen patients were included. The mean volume of GTV_ONCOwas larger than the GTV's defined from PET or MRI. The mean mismatch of the GTV_PATOcompared to the GTV_PET, GTV_MRIand GTV_ONCOwas 31.9 %, 54.5 % and 27.9 % respectively, and the entire GTV_PATO was only fully encompassed in GTV_ONCO in 1 of 13 patients. However, after the addition of a clinical 5 mm margin the GTV_PATO was fully encompassed in GTV_ONCO in 11 out of 13 patients.

CONCLUSIONS

Despite modern hybrid imaging modalities, a mismatch between imaging and pathological defined tumor volumes was observed in all patients.A 5 mm clinical margin was sufficient to ensure inclusion of the entire pathological volume in 11 out of 13 patients.

Delineation uncertainties of tumour volumes on MRI of head and neck cancer patients

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Role of target delineation uncertainties in head and neck cancer patients.

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Knowing contouring variations for MRI allows better adaptation of MRLinac for H&N cancers.

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An interobserver variation for GTV among 8 observers was below 2 mm using MRI.

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Variability between observers might improve using other imaging modalities.

Background

During the last decade, radiotherapy using MR Linac has gone from research to clinical implementation for different cancer locations. For head and neck cancer (HNC), target delineation based only on MR images is not yet standard, and the utilisation of MRI instead of PET/CT in radiotherapy planning is not well established. We aimed to analyse the inter-observer variation (IOV) in delineating GTV (gross tumour volume) on MR images only for patients with HNC.

Material/methods

32 HNC patients from two independent departments were included. Four clinical oncologists from Denmark and four radiation oncologists from Australia had independently contoured primary tumour GTVs (GTV-T) and nodal GTVs (GTV-N) on T2-weighted MR images obtained at the time of treatment planning. Observers were provided with sets of images, delineation guidelines and patient synopsis. Simultaneous truth and performance level estimation (STAPLE) reference volumes were generated for each structure using all observer contours. The IOV was assessed using the DICE Similarity Coefficient (DSC) and mean absolute surface distance (MASD).

Results

32 GTV-Ts and 68 GTV-Ns were contoured per observer. The median MASD for GTV-Ts and GTV-Ns across all patients was 0.17 cm (range 0.08–0.39 cm) and 0.07 cm (range 0.04–0.33 cm), respectively. Median DSC relative to a STAPLE volume for GTV-Ts and GTV-Ns across all patients were 0.73 and 0.76, respectively. A significant correlation was seen between median DSCs and median volumes of GTV-Ts (Spearman correlation coefficient 0.76, p < 0.001) and of GTV-Ns (Spearman correlation coefficient 0.55, p < 0.001).

Conclusion

Contouring GTVs in patients with HNC on MRI showed that the median IOV for GTV-T and GTV-N was below 2 mm, based on observes from two separate radiation departments. However, there are still specific regions in tumours that are difficult to resolve as either malignant tissue or oedema that potentially could be improved by further training in MR-only delineation.

Endoscopic diagnosis value of narrow band imaging Ni classification in vocal fold leukoplakia and early glottic cancer

OBJECTIVES

To explore the diagnostic value and the correlation between histological diagnosis and the Ni classification under narrow band imaging (NBI) for vocal fold leukoplakia (VFL) and early glottic cancer.

METHODS

A total of 91 patients with 119 vocal fold lesions were selected from January 2017 to May 2020. All these patients were subsequently examined by white light imaging (WLI) and NBI endoscopy, and then all lesions were classified by the Ni classification according to the characteristics of intraepithelial papillary capillary loop (IPCL) observed. The gold standard of diagnosis was histopathological results. Eventually, the chi-square and kappa test were applied, respectively, to evaluate the diagnostic value of NBI endoscopy and the consistency of Ni classification and pathological results.

RESULTS

The accuracy and sensitivity of NBI endoscopy were significantly higher than that of WLI endoscopy (P < 0.05). For the diagnosis of precancerous lesions under the NBI, the sensitivity, specificity, positive and negative predictive value were 69.6% (16/23), 90.6% (87/96), 64.0% (16/25) and 92.6% (87/94), which for malignant lesions were 84.4% (65/77), 92.9% (39/42), 95.6% (65/68) and 76.5% (39/51). Moreover, for patients with low-grade intraepithelial neoplasia (mild and moderate dysplasia), type IV lesions accounted for the most (69.6 vs 30.4%; χ² = 36.961, P < 0.001). For high-grade intraepithelial neoplasia or carcinoma in situ, type Va lesions were predominant (χ² = 30.526, P < 0.001), while type Vb and Vc lesions were dominant in invasive carcinoma (χ² = 64.373, P < 0.001). Besides, the kappa test revealed that there was a high consistency between Ni classification and pathological diagnosis (Kappa = 0.667, P < 0.001).

CONCLUSIONS

The Ni classification can improve the diagnosis accuracy of vocal fold lesions which enables clear visualization of mucosal microvasculature. This is essential for the early diagnosis of VFL and early glottic cancer during routine endoscopic examination.

Diagnostic Value and Pathological Correlation of Narrow Band Imaging Classification in Laryngeal Lesions

OBJECTIVES

To explore the diagnostic value and pathological correlation of narrow band imaging (NBI) classification in laryngeal lesions.

METHODS

A total of 112 patients (123 lesions) with laryngeal lesions from July 2018 to May 2019 were selected in this study. All patients were examined by NBI and white light imaging endoscopy. The NBI endoscopy was applied to classify the observed lesion sites according to intraepithelial papillary capillary loop pattern. The gold standard of diagnosis was pathological results. To evaluate the consistency of NBI classification and pathological results.

RESULTS

The sensitivity, specificity, positive predictive value, and negative predictive value of the diagnosis for benign, precancerous, and malignant lesions under the NBI endoscopy were 90.91%, 81.19%, 74.07%, 85.42%; 41.67%, 92.93%, 58.82%, 86.79%; and 93.51%, 65.22%, 91.14%, 68.18%, respectively. There was a high consistency between NBI classification and pathological results (κ = 0.679, P < .001).

CONCLUSIONS

The NBI classification can improve the accuracy of the diagnosis of laryngeal lesions. It is important for early diagnosis and treatment of vocal cord leukoplakia and laryngeal cancer.

Dose accumulation to assess the validity of treatment plans with reduced margins in radiotherapy of head and neck cancer

BACKGROUND AND PURPOSE

Literature has reported reduced treatment toxicity in head-and-neck radiotherapy (HNRT) when reducing the planning target volume (PTV) margin from 5 to 3 mm but loco-regional control was not always preserved. This study used deformable image registration (DIR)-facilitated dose accumulation to assess clinical target volume (CTV) coverage in the presence of anatomical changes.

MATERIALS AND METHODS

VMAT plans for 12 patients were optimized using 3 or 5 mm PTV and planning risk volume (PRV) margins. The planning computed tomography (pCT) scan was registered to each daily cone beam CT (CBCT) using DIR. The inverse registration was used to reconstruct and accumulate dose (D acc ). CTV coverage was assessed using the dose-volume histogram (DVH) metric D 99 % acc and by individual voxel analysis. Both approaches included an uncertainty estimate using the 95% level of confidence.

RESULTS

D 99 % acc was less than 95% of the prescribed doseD presc for three cases including only one case where this was at the 95% level of confidence. However for many patients, the accumulated dose included a substantial volume of voxels receiving less than 95%D presc independent of margin expansion, which predominantly occurred in the subdermal region. Loss in target coverage was very patient specific but tightness of target volume coverage at planning was a common factor leading to underdosage.

CONCLUSION

This study agrees with previous literature that PTV/PRV margin reduction did not significantly reduce CTV coverage during treatment, but also highlighted that tight coverage of target volumes at planning increases the risk of clinically unacceptable dose delivery. Patient-specific verification of dose delivery to assess the dose delivered to each voxel is recommended.

Verification of HE-based CTV in laryngeal and hypopharyngeal cancer using pan-cytokeratin

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Currently clinical CTV margins lack evidence and need (histopathological) validation.

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Tumor outline on HE and pan-cytokeratin staining are comparable for laryngeal cancer.

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HE-based delineations can be used for histopathology based CTV-margin definition.

Background

For accurate target definition, we determined margins for the clinical target volume (CTV) for laryngeal and hypopharyngeal cancer in computed tomography (CT, 4.3 mm), magnetic resonance imaging (MR, 6.1 mm) and fluorodeoxyglucose (FDG)-positron emission tomography (PET, 5.2 mm). Previously, we used Hematoxylin-eosin (HE) stained whole-mount sections of total laryngectomy specimens as gold standard to define CTV margins. In the present study, we verified the HE-based tumor delineation with staining for pan-cytokeratin, specific for squamous cell carcinoma.

Methods

Twenty-seven patients with a T3/T4 laryngeal hypopharyngeal tumor were included. From each patient, a total laryngectomy specimen was obtained. Four subsequent 3-mm thick slices containing tumor were selected of which 4-µm thick whole-mount sections were obtained and stained with HE and for pan-cytokeratin CK-AE1/3. Tumors were microscopically delineated on both sections by an experienced head-and-neck pathologist. Tumor delineations were compared using the conformity index (CI) and the distance between both contours.

Results

The CI between HE-based and CK-AE1/3-based tumor delineations was 0.87. The maximum and 95th percentile (p95) extent of the HE-based tumor delineations from the CK-AE1/3-based tumor delineations were 1.7 mm and 0.7 mm, respectively. The maximum and p95 extent of the CK-AE1/3-based tumor delineations from the HE-based tumor delineations was 1.9 mm and 0.8 mm, respectively.

Conclusions

Histopathological assessment of tumor outline on standard HE-stained sections is comparable to microscopic tumor extent based on squamous cell specific pan-cytokeratin staining. Therefore, CTV margins based on HE based tumor contour will be adequate.

Evaluation of diffusion weighted imaging for tumor delineation in head-and-neck radiotherapy by comparison with automatically segmented 18F-fluorodeoxyglucose positron emission tomography

Background and purpose

Diffusion weighted (DW) MRI may facilitate target volume delineation for head-and-neck (HN) radiation treatment planning. In this study we assessed the use of a dedicated, geometrically accurate, DW-MRI sequence for target volume delineation. The delineations were compared with semi-automatic segmentations on ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) images and evaluated for interobserver variation.

Methods and materials

Fifteen HN cancer patients underwent both DW-MRI and FDG-PET for RT treatment planning. Target delineation on DW-MRI was performed by three observers, while for PET a semi-automatic segmentation was performed using a Gaussian mixture model. For interobserver variation and intermodality variation, volumes, overlap metrics and Hausdorff distances were calculated from the delineations.

Results

The median volumes delineated by the three observers on DW-MRI were 10.8, 10.5 and 9.0 cm³ respectively, and was larger than the median PET volume (8.0 cm³). The median conformity index of DW-MRI for interobserver variation was 0.73 (range 0.38–0.80). Compared to PET, the delineations on DW-MRI by the three observers showed a median dice similarity coefficient of 0.71, 0.69 and 0.72 respectively. The mean Hausdorff distance was small with median (range) distances between PET and DW-MRI of 2.3 (1.5–6.8), 2.5 (1.6–6.9) and 2.0 (1.35–7.6) mm respectively. Over all patients, the median 95th percentile distances were 6.0 (3.0–13.4), 6.6 (4.0–24.0) and 5.3 (3.4–26.0) mm.

Conclusion

Using a dedicated DW-MRI sequence, target volumes could be defined with good interobserver agreement and a good overlap with PET. Target volume delineation using DW-MRI is promising in head-and-neck radiotherapy, combined with other modalities, it can lead to more precise target volume delineation.

Technical Note: Diffusion-weighted MRI with minimal distortion in head-and-neck radiotherapy using a turbo spin echo acquisition method

PURPOSE

Diffusion-weighted (DW) MRI, showing high contrast between tumor and background tissue, is a promising technique in radiotherapy for tumor delineation. However, its use for head-and-neck patients is hampered by poor geometric accuracy in conventional echo planar imaging (EPI) DW-MRI. An alternative turbo spin echo sequence, DW-SPLICE, is implemented and demonstrated in patients.

METHODS

The DW-SPLICE sequence was implemented on a 3.0 T system and evaluated in 10 patients. The patients were scanned in treatment position, using a customized head support and immobilization mask. Image distortions were quantified at the gross tumor volume (GTV) using field map analysis. The apparent diffusion coefficient (ADC) was evaluated using an ice water phantom.

RESULTS

The DW images acquired by DW-SPLICE showed no image distortions. Field map analysis at the gross tumor volumes resulted in a median distortion of 0.2 mm for DW-SPLICE, whereas for the conventional method this was 7.2 mm. ADC values, measured using an ice water phantom were in accordance with literature values.

CONCLUSIONS

The implementation of DW-SPLICE allows for diffusion-weighted imaging of patients in treatment position with excellent geometrical accuracy. The images can be used to facilitate target volume delineation in RT treatment planning.

Modality-specific target definition for laryngeal and hypopharyngeal cancer on FDG-PET, CT and MRI

BACKGROUND AND PURPOSE

The goal of this study was to improve target definition by deriving modality-specific margins for clinical target volumes (CTV) for laryngeal and hypopharyngeal cancer on CT, MRI and 18-FDG-PET.

MATERIAL AND METHODS

Twenty-five patients with T3/T4 laryngeal/hypopharyngeal cancer underwent CT, MRI and 18-FDG-PET scans before laryngectomy. HE-sections were obtained from the surgical specimen and tumor was delineated (tumor_HE). The GTVs on CT and MRI were delineated in consensus. PET-based GTVs were automatically segmented. The three-dimensionally reconstructed specimen was registered to the various images. Modality-specific CTV margins were derived and added to the GTVs to achieve adequate tumor coverage. The resulting CTVs were compared with each other, to tumor_HE, and to CTV_CT10 constructed on CT with the clinical margin of 10mm.

RESULTS

CTV margins of 4.3mm (CT), 6.1mm (MRI) and 5.2mm (PET) were needed to achieve adequate tumor coverage. The median volumes of the resulting modality-specific CTVs were 44ml (CT), 48ml (MRI) and 39ml (PET), while the CTV_10mm was 80ml.

CONCLUSION

For laryngohypopharyngeal tumors, 45-52% target volume reduction compared with CTV_10mm is achievable when modality-specific CTV margins are used. PET-based CTVs were significantly smaller compared to CT- and MRI-based CTVs.

How to minimize morbidity in radiotherapy of pharyngolaryngeal tumors?

PURPOSE OF REVIEW

Radiotherapy is one of the most effective treatment modalities for head and neck cancer. However, because of the intricacy between tumors and normal tissues, it can induce morbidity, such as mucositis, dermatitis, xerostomia, dysphagia, hearing loss, vision impairment, skin fibrosis, and osteoradionecrosis of the jaw, and it can dramatically impact on patient quality of life.

RECENT FINDINGS

Throughout the last decade, significant improvements have been made in head and neck cancer radiotherapy, especially with the introduction on a routine basis of intensity-modulated radiotherapy.

SUMMARY

In this context, this review manuscript will focus on how the implementation of intensity-modulated radiotherapy influences treatment morbidity. Specifically, the issues of target volume and organ-at-risk delineation, sparing of organs at risk, tailored treatment intensity, adaptive treatment, and the use of proton therapy will be discussed.

CT-based volumetric tumor growth velocity: A novel imaging prognostic indicator in oropharyngeal cancer patients receiving radiotherapy

OBJECTIVES

Volumetric tumor growth velocity (TGV) reflects in vitro tumor aggressiveness, but its prognostic value has not been investigated in vivo. We examined the prognostic impact of TGV on oncologic outcomes in patients with oropharyngeal squamous cell cancer (OSCC).

MATERIALS AND METHODS

101 OSCC patients with two pretreatment CTs with time gap of 2 or more weeks treated at a single institution between 2004 and 2008 were identified. Primary tumor and nodal targets were segmented in scans. Linear growth rates were calculated. Recursive partitioning analysis (RPA) identified cut point associated with outcomes.

RESULTS

Median follow-up was 59months (range 7-118). Median primary TGV was 0.65% increase per day (range 0-9.37%). RPA identified TGV cut point associated with local control (LC) of 1% per day. Patients with higher TGV had decreased 5-year LC (73% vs. 98%, p=0.0004), distant control (DC, 62% vs. 91%, p=0.0007), and overall survival (OS, 38% versus 93%, p<0.0001). In multivariate analysis including demographics, tumor stage, subsite, and treatment factors, TGV⩾1% per day independently predicted worsened LC (p = 0.02), DC (p = 0.003), and OS (p < 0.0001). However, this TGV cutoff was not significantly predictive of LC, DC, or OS for a subset of presumed HPV-positive patients.

CONCLUSION

OSCC TGV⩾1% per day is a substantive negative prognostic indicator for disease control and overall survival, particularly in HPV non-associated tumors. This novel CT-based volumetric assessment of TGV suggests a simple methodology for risk stratification of patients.

Validated guidelines for tumor delineation on magnetic resonance imaging for laryngeal and hypopharyngeal cancer

BACKGROUND

Validation of magnetic resonance imaging (MRI) and development of guidelines for the delineation of the gross tumor volume (GTV) is of utmost importance to benefit from the visibility of anatomical details on MR images and to achieve an accurate GTV delineation. In the ideal situation, the GTV delineation corresponds to the histopathologically determined 'true tumor volume'. Consequently, we developed guidelines for GTV delineation of laryngeal and hypopharyngeal tumors on MRI and determined the accuracy of the resulting delineation of the tumor outline on histopathology as gold standard.

MATERIAL AND METHODS

Twenty-seven patients with T3 or T4 laryngeal/hypopharyngeal cancer underwent a MRI scan before laryngectomy. Hematoxylin and eosin sections were obtained from surgical specimens and tumor was delineated by one pathologist. GTV was delineated on MR images by three independent observers in two sessions. The first session (del1) was performed according to clinical practice. In the second session (del2) guidelines were used. The reconstructed specimen was registered to the MR images for comparison of the delineated GTVs to the tumor on histopathology. Volumes and overlap parameters were analyzed. A target margin needed to assure tumor coverage was determined.

RESULTS

The median GTVs (del1: 19.4 cm³, del2: 15.8 cm³) were larger than the tumor volume on pathology (10.5 cm³). Comparable target margins were needed for both delineation sessions to assure tumor coverage. By adding these margins to the GTVs, the target volumes for del1 (median: 81.3 cm³) were significantly larger than for del2 (median: 64.2 cm³) (p ≤ 0.0001) with similar tumor coverage.

CONCLUSIONS

In clinical radiotherapy practice, the delineated GTV on MRI is twice as large as the tumor volume. Validated delineation guidelines lead to a significant decrease in the overestimation of the tumor volume.