Patterns of locoregional failure following post-operative intensity-modulated radiotherapy to oral cavity cancer: quantitative spatial and dosimetric analysis using a deformable image registration workflow

Patterns of relapse after postoperative radiotherapy in patients with oral cavity cancer and a flap

PURPOSE

Reconstructive surgery with a flap is standard practice in advanced oral cavity squamous cell carcinoma to restore essential functions. However, these functions may be compromised by postoperative radiotherapy. This study evaluates relapse patterns and treatment-related toxicity in these patients.

METHODS AND MATERIALS

A multicentre 2018-2023 study included 247 patients with oral cavity squamous cell carcinoma. Uni- and multivariate analyses estimated the cumulative incidence of locoregional failures, survival rates, and prognostic factors.

RESULTS

Among the patients, 74.0 % had pT3-4 tumours, 78.5 % had free flaps, regional pedicled flaps (12.6 %), or local flaps (8.5 %). Flaps were not delineated on planning CTs. Median follow-up for living patient was 36.8months. Fifty-eight patients (23.0 %) had involved soft-tissue margins; no correlation was found between margin involvement, stage, or flap type. Forty patients experienced local relapse within a median of 8.23months. Local relapse rates were higher in patients with involved (28.6 %) versus clear margins (9.3 %, P<0.004). Two-year locoregional relapse and survival rates were 17.8 %, and 74.3 %, respectively. Performance status greater than 1, locoregional relapse, and distant relapse were associated with poorer survival. Coregistration of planning-relapse CTs is challenging due to flap changes, limiting relapse pattern analysis. Subgroup analysis of locoregional relapses (14 out of 53) at the main contributing centre revealed that five relapses occurred at the native tissue-flap junction, with minor flap involvement in two cases and no intraflap failure. All other relapses occurred outside the flap.

CONCLUSIONS

Involved margin rates correlating with increased local relapse risk and were not different according flap type. Further investigation into flap segmentation and planning optimization is needed. The OPTIFLAP trial (NCT06798922, PHRC2024) aims to determine whether radiotherapy can be optimized to spare flaps without increasing the risk of locoregional failure.

Combined Spatial and Dosimetric Recurrence Pattern Analysis in Head and Neck Squamous Cell Carcinoma Following Postoperative (Chemo)radiotherapy

BACKGROUND

Advancements in nodal staging for head and neck squamous cell carcinoma (HNSCC) have prompted radiotherapy de-escalation trials to reduce irradiation of electively treated neck regions, with the goal of improving treatment tolerability. While volumetric de-escalation has shown promise in definitive radiotherapy of HNSCC, limited data exist regarding its safety in the postoperative treatment setting. This study aimed to assess dose-level-specific locoregional recurrence patterns following standard postoperative (chemo)radiotherapy in a mixed HNSCC cohort to inform risk-adaptive radiotherapy strategies.

MATERIALS AND METHODS

We retrospectively reviewed 203 HNSCC patients (75% HPV-negative, 25% HPV-positive) treated with curative intent postoperative (chemo)radiotherapy from 2017 to 2021. Recurrence imaging was co-registered with planning CT, and recurrent tumor volumes were dosimetrically compared to the target volume dose and spatially analyzed using a center-of-mass-based approach. We classified five recurrence types: A (central high-dose), B (peripheral high-dose), C (central intermediate- or low-dose), D (peripheral intermediate- or low-dose), and E (extraneous dose).

RESULTS

With a median follow-up of 39.7 months, the three-year local, regional, and distant control of HPV-negative HNSCC were 84%, 87%, and 87%, respectively. Of 56 recurrences, 17 were local, 13 regional, 3 locoregional, 9 combined local/regional with concomitant distant failure, and 14 distant only. Of 40 analyzed recurrences, we identified 47.5% as type A/B, 5% as type C/D intermediate-dose, and 20% as type E, half of which were secondary cancers. Among the 27.5% (11/40) type C/D low-dose recurrences in the elective target volume, 15% (6/40) were true nodal failures, resulting in an overall elective neck failure rate of 3% (6/203).

CONCLUSION

The predominance of high-dose recurrences suggests that biological tumor resistance is a key driver of treatment failure, highlighting the necessity to refine postoperative risk stratification and integrate tumor biology into dose escalation decisions. The low incidence of isolated nodal recurrences in electively treated neck regions supports the feasibility of volumetric de-escalation of postoperative radiotherapy. This approach might not only be feasible for HPV-associated oropharyngeal cancers but also for HPV-negative tumors, provided that accurate nodal staging has been conducted.

Extra-capsular nodal extension after surgical resection for HPV-positive oropharyngeal Cancer: Adjuvant radiation versus chemoradiation

PURPOSE

The prognostic significance of extra-capsular nodal extension (ECE) after surgical resection for human papillomavirus (HPV)-positive oropharyngeal cancer is controversial, and the optimal choice of adjuvant therapy is uncertain in this setting.

METHODS AND MATERIALS

A review of institutional databases identified a total of 63 patients with pathological evidence of ECE in at least 1 cervical lymph node after transoral robotic surgery and neck dissection for HPV-positive squamous cell carcinoma of the oropharynx. Clinical outcomes were compared based on whether patients received adjuvant radiation (20 patients) or chemoradiation (43 patients). The Kaplan Meier method was used to determine survival statistics with comparisons between groups conducted with the log-rank test.

RESULTS

With a median follow-up of 50 months (range, 6 to 110 months), the 3-year overall survival for the entire population was 87 %. No significant difference was observed between patients treated by adjuvant radiation and chemoradiation with respect to 3-year overall survival (86 % versus 87 %, p = 0.45), local-regional control (91 % vs. 90 %, p = 0.71), and progression-free survival (83 % vs. 85 %, p = 0.57). Exploratory subset analysis of competing variables failed to identify any group in which the addition of chemotherapy to radiation improved outcome.

CONCLUSIONS

While the presence of ECE after surgical resection has historically been considered an indication for the use of concurrent chemoradiation in the adjuvant setting, these data suggest that this paradigm should be re-evaluated in the setting of HPV-positive oropharyngeal cancer.

Patterns of loco-regional progression and patient outcomes after definitive-dose radiation therapy for anaplastic thyroid cancer

BACKGROUND

The aim of this study is to characterize the patterns of loco-regional progression (LRP) and outcomes after definitive-dose intensity modulated radiation therapy (IMRT) for anaplastic thyroid cancer (ATC) with macroscopic neck disease at the time of IMRT.

METHODS

Disease/treatment characteristics and outcomes for patients with unresected or incompletely resected ATC who received IMRT (≥45 Gy) were retrospectively reviewed. For those with LRP after IMRT, progressive/recurrent gross tumor volumes (rGTV) were contoured on diagnostic CTs and co-registered with initial planning CTs using deformable image registration. rGTVs were classified based on established spatial/dosimetric criteria.

RESULTS

Forty patients treated between 2010-2020 formed the cohort. Median IMRT dose was 66 Gy (45-70 Gy); altered fractionation (AF) was used in 24 (60 %). All received concurrent chemotherapy. In addition to areas of gross disease, target volumes (TVs) commonly included: central compartment/upper mediastinum (levels VI/VII), neck levels II-V in an involved, and levels III-IV in an uninvolved lateral neck. Median overall survival was 7.1 m. Median progression free survival was 7.4 m for patients with locoregional disease and 1.8 m for patients with distant metastasis at the time of IMRT. Twenty-one patients (53 %) developed LRP at median of 10.9 m; freedom from LRP at 3 m and 12 m was 71 % (95 %CI 58-87 %) and 47 % (95 %CI 32-68 %). Forty-one individual rGTVs were identified and most occurred within the high dose (HD) TVs: Type A/central HD (n = 29, 71 %) and B/peripheral HD (n = 3, 7 %).

CONCLUSIONS

Despite an intensive treatment schedule, including AF and concurrent chemotherapy, classic radio-resistant and rapid Type A failures predominated; isolated extraneous dose failures were rare. While these findings support the IMRT and TV delineation strategies described herein, they highlight the importance of identifying novel strategies to further improve LRC for patients with unresectable disease without targetable mutations for contemporary neo-adjuvant strategies.

Interpreting the patterns of local failure following postoperative volumetric-modulated arctherapy in oral cavity and oropharynx cancers: Impact of the different methods of analysis

PURPOSE

Intensity-modulated radiation therapy or volumetric-modulated arctherapy is nowadays the recommended radiation technique for the treatment of head and neck cancers. However, by providing a significant dose gradient between target volumes and organs at risk, there is a risk of target missing and thus recurrence in case of inadequate delineation. It is therefore necessary to determine the origin of these recurrences to improve clinical practice. Over the past years, different methods have been described for the analysis of recurrences. Using the patterns of failure of patients with oral cavity and oropharynx carcinoma, treated with postoperative volumetric-modulated arctherapy in our institution, the purpose of this work was to analyse the sites of local recurrences and to evaluate the disparity in the classification of recurrences when different methods were used.

MATERIAL AND METHODS

Between 2011 and 2019, 167 patients who underwent postoperative volumetric-modulated arctherapy for oral cavity or oropharyngeal cancers were included (60 and 40 % respectively). Two or three dose levels were prescribed (54Gy, 59.4/60Gy±66Gy). Local recurrence occurred in 17 patients (10.2 %). We assessed the patterns of local recurrences according to four methods: 1/ volume-based method using the volume overlap between the recurrence volume and initial target volumes; 2/ volume-based method of overlap between the recurrence volume and the 95 % treatment isodose; 3/ point-based method using the position of the barycentre of the recurrence volume; 4/ combined centroid method classifying recurrences according to both the initial target volumes and dose distribution. Each case was reviewed to make a clinical judgment on these classifications and assessed them as "appropriate", "possible", or "inappropriate".

RESULTS

For the volume-based method using overlap between the recurrence volume and the initial clinical target volume, this classification was clinically judged as inappropriate in 11 out of 17 cases (65 %). For the volume-based method using overlap between the recurrence volume and the 95 % prescribed isodose, this classification was clinically judged as appropriate in 15 out of 17 cases (88 %). For the point-based method, this classification was clinically judged as appropriate in 14 out of 17 cases (82 %). Thirteen out of 17 local recurrences had the same classification between this point-based method and the volume-based method of overlap between the recurrence volume and the 95 % prescribed isodose. For the combined centroid method, among 17 local recurrences nine were classified as type A, two as type B, two as type C, three as type D and one as type E. This classification was clinically judged as appropriate in 15 out of 17 cases (88 %). Only five out of 17 of the local recurrences were classified the same way according to the four different methods (29 %).

CONCLUSION

Recurrences that are "marginal" or "outfield" represent a major challenge for intensity-modulated radiation therapy/volumetric-modulated arctherapy quality assurance and improvement of delineation recommendations. To date, there are no published methods that give complete satisfaction.

High-dose loco-regional pattern of failure after primary radiotherapy in p16 positive and negative head and neck squamous cell carcinoma - A DAHANCA 19 study

Introduction

Patients with failure after primary radiotherapy (RT) for head and neck squamous cell carcinoma (HNSCC) have a poor prognosis. This study investigates pattern of failure after primary curatively intended IMRT in a randomized controlled trial in relation to HPV/p16 status.

Material and methods

Patients with HNSCC of the oral cavity, oropharynx (OPSCC), hypopharynx or larynx were treated with primary curative IMRT (+/-cisplatin) and concomitant nimorazole between 2007 and 12. Of 608 patients, 151 had loco-regional failure within five years, from whom 130 pairs of scans (planning-CT and diagnostic failure scan) were collected and deformably co-registered. Point of origin-based pattern of failure analysis was conducted, including distance to CTV1 and GTV, and estimated dose coverage of the point of origin.

Results

Of 130 patients with pairs of scans, 104 (80 %) had at least one local or regional failure site covered by 95 % of prescribed dose and 87 (67 %) of the failures had point of origin within the high-dose CTV (CTV1). Of failures from primary p16 + OPSCC, the majority of both mucosal (84 %) and nodal (61 %) failures were covered by curative doses. For p16- tumors (oral cavity, OPSCC p16neg, hypopharynx and larynx), 75 % of mucosal and 66 % of nodal failures were high-dose failures.

Conclusion

Radioresistance is the primary cause of failure after RT for HNSCC irrespective of HPV/p16 status. Thus, focus on predictors for the response to RT is warranted to identify patients with higher risk of high-dose failure that might benefit from intensified treatment regimens.

[Issues and implementation of postoperative radiotherapy after flap reconstructive surgery in head and neck cancers]

The management of head and neck cancers is multidisciplinary, often relying on the use of combined treatments to maximize the chances of cure. Combined treatments are however also responsible for cumulative side effects. The aim of reconstructive surgery with a flap is to restore a function lost with the loss of substance from the tumor resection. However, changes in reconstructive surgery have impact of postoperative radiotherapy planning. The optimization of imaging protocols for radiotherapy planning should make it possible to identify postoperative changes and to distinguish flaps from surrounding native tissues to delineate the flaps and document the spontaneous evolution of these flaps or dose-effect relationships in case of radiotherapy. Such changes include atrophy, fibrosis of soft tissue flaps and osteoradionecrosis of bone flaps. Radiotherapy optimization also involves standardization of the definition of target volumes in situations where a flap is present, a situation that is increasingly common in routine care. This evolution of practice, beyond the essential multidisciplinary consultation meetings defining treatment indications, requires a close radio surgical collaboration with respect to technical aspects of the two disciplines. Doing so, anticipation of relapse and toxicity profiles could possibly lead to propose strategies for personalized de-escalation of multimodal treatments through interdisciplinary trials.

Reconstructive flap surgery in head and neck cancer patients: an interdisciplinary view of the challenges encountered by radiation oncologists in postoperative radiotherapy

Background

Major advances have been made in reconstructive surgery in the last decades to reduce morbidity in head and neck cancer. Flaps are now present in 80% of patients with oral cavity cancer to cover anatomic, functional, and cosmetic needs. However, gaps in interdisciplinary innovation transfer from surgery to postoperative radiotherapy (poRT) remain challenging. We aimed to provide an interdisciplinary view of the challenges encountered by radiation oncologists in planning head and neck postoperative radiotherapy.

Methods

A systematic and critical review was conducted to address areas of optimization in surgery and radiology that may be relevant to poRT.

Results

Despite extensive surgical literature on flap techniques and salvage surgery, 13 retrospective series were identified, where flap outcomes were indirectly compared between surgery alone or poRT. These low-evidence studies suggest that radiotherapy accelerates flap atrophy, fibrosis, and osteoradionecrosis and deteriorates functional outcomes. Preliminary evidence suggests that tumor spread occurs at the flap-tissue junction rather than in the flaps. One prospective 15-patient study showed 31.3% vs. 39.2% flap volume reduction without or with poRT. In an international consensus, experts recognized the needs for optimized flap-sparing poRT against flap-related functional deterioration and bone damage. CT, MRI, and PET-CT modalities show potential for the delineation of the junction area between native tissues and flap for flap segmentation and to characterize flap-specific changes quantitatively and correlate them with patterns of relapse or complications.

Conclusion

Flap management in poRT is insufficiently documented, but poRT seems to damage flaps. Current gaps in knowledge underscore the need for prospective flap assessment and interdisciplinary trials investigating flap morbidity minimization by flap-sparing poRT planning.

Patterns of failure for recurrent head and neck squamous cell carcinoma treated with salvage surgery and postoperative IMRT reirradiation

Purpose/Objectives

The purpose of this study was to evaluate patterns of locoregional recurrence (LRR) after surgical salvage and adjuvant reirradiation with IMRT for recurrent head and neck squamous cell cancer (HNSCC).

Materials/Methods

Patterns of LRR for 61 patients treated consecutively between 2003 and 2014 who received post-operative IMRT reirradiation to ≥ 60 Gy for recurrent HNSCC were determined by 2 methods: 1) physician classification via visual comparison of post-radiotherapy imaging to reirradiation plans; and 2) using deformable image registration (DIR). Those without evaluable CT planning image data were excluded. All recurrences were verified by biopsy or radiological progression. Failures were defined as in-field, marginal, or out-of-field. Logistic regression analyses were performed to identify predictors for LRR.

Results

A total of 55 patients were eligible for analysis and 23 (42 %) had documented LRR after reirradiation. Location of recurrent disease prior to salvage surgery (lymphatic vs. mucosal) was the most significant predictor of LRR after post-operative reirradiation with salvage rate of 67 % for lymphatic vs. 33 % for mucosal sites (p = 0.037). Physician classification of LRR yielded 14 (61 %) in-field failures, 3 (13 %) marginal failures, and 6 (26 %) out-of-field failures, while DIR yielded 10 (44 %) in-field failures, 4 (17 %) marginal failures, and 9 (39 %) out-of-field failures. Most failures (57 %) occurred within the original site of recurrence or first echelon lymphatic drainage. Of patients who had a free flap placed during salvage surgery, 56 % of failures occurred within 1 cm of the surgical flap.

Conclusion

Our study highlights the role of DIR in enhancing the accuracy and consistency of POF analysis. Compared to traditional visual inspection, DIR reduces interobserver variability and provides more nuanced insights into dose-specific and spatial parameters of locoregional recurrences. Additionally, the study identifies the location of the initial recurrence as a key predictor of subsequent locoregional recurrence after salvage surgery and re-IMRT.

Mapping Local Failure Following Bladder Radiotherapy According to Dose

AIMS

To determine the relationship between local relapse following radical radiotherapy for muscle-invasive bladder cancer (MIBC) and radiation dose.

MATERIALS AND METHODS

Patients with T2-4N0-3M0 MIBC were recruited to a phase II study assessing the feasibility of intensity-modulated radiotherapy to the bladder and pelvic lymph nodes. Patients were planned to receive 64 Gy/32 fractions to the bladder tumour, 60 Gy/32 fractions to the involved pelvic nodes and 52 Gy/32 fractions to the uninvolved bladder and pelvic nodes. Pre-treatment set-up was informed by cone-beam CT. For patients who experienced local relapse, cystoscopy and imaging (CT/MRI) was used to reconstruct the relapse gross tumour volume (GTVrelapse) on the original planning CT . GTVrelapse D98% and D95% was determined by co-registering the relapse image to the planning CT utilising deformable image registration (DIR) and rigid image registration (RIR). Failure was classified into five types based on spatial and dosimetric criteria as follows: A (central high-dose failure), B (peripheral high-dose failure), C (central elective dose failure), D (peripheral elective dose failure) and E (extraneous dose failure).

RESULTS

Between June 2009 and November 2012, 38 patients were recruited. Following treatment, 18/38 (47%) patients experienced local relapse within the bladder. The median time to local relapse was 9.0 months (95% confidence interval 6.3-11.7). Seventeen of 18 patients were evaluable based on the availability of cross-sectional relapse imaging. A significant difference between DIR and RIR methods was seen. With the DIR approach, the median GTVrelapse D98% and D95% was 97% and 98% of prescribed dose, respectively. Eleven of 17 (65%) patients experienced type A failure and 6/17 (35%) patients type B failure. No patients had type C, D or E failure. MIBC failure occurred in 10/17 (59%) relapsed patients; of those, 7/11 (64%) had type A failure and 3/6 (50%) had type B failure. Non-MIBC failure occurred in 7/17 (41%) patients; 4/11 (36%) with type A failure and 3/6 (50%) with type B failure.

CONCLUSION

Relapse following radiotherapy occurred within close proximity to the original bladder tumour volume and within the planned high-dose region, suggesting possible biological causes for failure. We advise caution when considering margin reduction for future reduced high-dose radiation volume or partial bladder radiotherapy protocols.

Impact of the method chosen for the analysis of recurrences after radiotherapy for head and neck cancers: volume-based, point-based and combined methods

Intensity modulated radiation therapy for head and neck is a complex technique. Inappropriate delineation and/or dose distribution can lead to recurrences. Analysis of these recurrences should lead to improve clinical practice. For several years, different methods of analysis have been described. The purpose of this review is to describe these different methods and to discuss their advantages and limitations. The first published methods used a volume-based approach studying the entire volume of recurrence according to initial target volumes, or dose distribution. The main limitation of these methods was that the volume of recurrence studied was dependent on the delay in diagnosis of that recurrence. Subsequently, other methods used point-based approaches, conceptualizing recurrence either as a spherical expansion from a core of radioresistant cells (center of mass of recurrence volume) or using a more clinical approach, taking into account tumor expansion pathways. More recently, more precise combined methods have been described, combining the different approaches. The choice of method is decisive for conclusions on the origin of recurrence.

Head and Neck Cancer Adaptive Radiation Therapy (ART): Conceptual Considerations for the Informed Clinician

For nearly 2 decades, adaptive radiation therapy (ART) has been proposed as a method to account for changes in head and neck tumor and normal tissue to enhance therapeutic ratios. While technical advances in imaging, planning and delivery have allowed greater capacity for ART delivery, and a series of dosimetric explorations have consistently shown capacity for improvement, there remains a paucity of clinical trials demonstrating the utility of ART. Furthermore, while ad hoc implementation of head and neck ART is reported, systematic full-scale head and neck ART remains an as yet unreached reality. To some degree, this lack of scalability may be related to not only the complexity of ART, but also variability in the nomenclature and descriptions of what is encompassed by ART. Consequently, we present an overview of the history, current status, and recommendations for the future of ART, with an eye toward improving the clarity and description of head and neck ART for interested clinicians, noting practical considerations for implementation of an ART program or clinical trial. Process level considerations for ART are noted, reminding the reader that, paraphrasing the writer Elbert Hubbard, "Art is not a thing, it is a way."