Evaluation of survival outcome and prognostic factors for oral cavity cancer treated with volumetric arc therapy

PURPOSE

This study aimed to evaluate the survival outcomes and identify prognostic factors for patients with oral cavity cancer (OCC) who underwent adjuvant treatment with volumetric arc therapy (VMAT) using simultaneous integrated boost (SIB).

METHODS

Data was collected for post-operated patients of carcinoma of oral cavity who received adjuvant VMAT with SIB between June 2018 and December 2022. The data was entered and analyzed using SPSS software version 20.0. Survival rates were estimated using Kaplan Meier method. To determine survival difference between the groups, log rank test was used. Multivariate analyses were performed with Cox proportional hazard model and p value < 0.05 was considered as significant.

RESULTS

A total of 178 patients were included in the study. The median follow-up period was 26 months (range 3-56 months). The 3-year OS, DFS, and LRC rates were 78% (95% CI 77-79%), 76% (95% CI 74-77%), and 81% (95% CI 80-82%), respectively. Univariate analysis identified age ≥ 50 years, lymph node involvement, extracapsular extension (ECE), and N2-N3 disease as significant adverse prognostic factors for OS, DFS, and LRC. Multivariate analysis confirmed age ≥ 50 years and nodal involvement as independent predictors of worse OS, DFS, and LRC. Additionally, ECE independently affected OS and DFS.

CONCLUSION

Adjuvant treatment with VMAT using SIBin patients with OCC is effective. Age and nodal involvement had significant impact on LRC, DFSand OS while ECE on DFSand OS.

Outcomes among oropharyngeal and oral cavity cancer patients treated with postoperative volumetric modulated arctherapy

Background

Presently, there are few published reports on postoperative radiation therapy for oropharyngeal and oral cavity cancers treated with IMRT/VMAT technique. This study aimed to assess the oncological outcomes of this population treated with postoperative VMAT in our institution, with a focus on loco-regional patterns of failure.

Material and methods

Between 2011 and 2019, 167 patients were included (40% of oropharyngeal cancers, and 60% of oral cavity cancers). The median age was 60 years. There was 64.2% of stage IV cancers. All patients had both T and N surgery. 34% had a R1 margin, 42% had perineural invasion. 72% had a positive neck dissection and 42% extranodal extension (ENE). All patients were treated with VMAT with simultaneous integrated boost with three dose levels: 66Gy in case of R1 margin and/or ENE, 59.4-60Gy on the tumor bed, and 54Gy on the prophylactic areas. Concomittant cisplatin was administrated concomitantly when feasible in case of R1 and/or ENE.

Results

The 1- and 2-year loco-regional control rates were 88.6% and 85.6% respectively. Higher tumor stage (T3/T4), the presence of PNI, and time from surgery >45 days were significant predictive factors of worse loco-regional control in multivariate analysis (p=0.02, p=0.04, and p=0.02). There were 17 local recurrences: 11 (64%) were considered as infield, 4 (24%) as marginal, and 2 (12%) as outfield. There were 9 regional recurrences only, 8 (89%) were considered as infield, and 1 (11%) as outfield. The 1- and 2-year disease-free survival (DFS) rates were 78.9% and 71.8% respectively. The 1- and 2-year overall survival (OS) rates were 88.6% and 80% respectively. Higher tumor stage (T3/T4) and the presence of ENE were the two prognostic factors significantly associated with worse DFS and OS in multivariate analysis.

Conclusion

Our outcomes for postoperative VMAT for oral cavity and oropharyngeal cancers are encouraging, with high rates of loco-regional control. However, the management of ENE still seems challenging.

Postoperative radiotherapy for supraglottic cancer on real-world data: can we reduce dose to lymph node levels?

PURPOSE

To evaluate prognosis for reducing postoperative radiotherapy (PORT) dose to lymph node levels of supraglottic cancer (SC) on real-world data.

METHOD AND MATERIALS

Patients were derived from two cancer centers. In center 1, the involved nodal levels (high-risk levels, HRL) and the next level received a dose of 60.06 Gy/1.82 Gy per fraction, while the other uninvolved levels (low-risk levels, LRL) received 50.96 Gy/1.82 Gy per fraction. In center 2, all received 50 Gy/2 Gy per fraction. The rates of high-risk levels control (HRC), regional control (RC), overall survival (OS), progression-free survival (PFS) and distant metastasis-free survival (DMFS) were calculated by Kaplan-Meier method.

RESULT

Totally, 124 patients were included (62 in center 1, 62 in center 2). Most patients (106, 85.5%) had a stage T3/N + tumor. The median follow-up was 45 months (range 1-163 months). There were no significant differences in terms of OS (p = 0.126), RC (p = 0.514), PFS (p = 0.195) and DMFS (p = 0.834). Most regional recurrences (4, 80%) occurred within three years of treatment, and all occurred within the target volumes. No regional failure occurred in HRL in center 1, while three (3/4) failures occurred in center 2. Dose reduction prescription to HRL led to a lower HRC rate (100% vs. 90.6%, p = 0.009). While the rates of LRL control (98.4%) were equal between the two centers.

CONCLUSION

Compared with a standard dose, the reduced dose to involved nodal levels showed inferior regional control for PORT, while uninvolved nodal levels showed equal outcomes. A dose of 50 Gy for HRL may be an unfavorable treatment option for SC.

Impact of upgraded radiotherapy system on outcomes in postoperative head and neck squamous cell carcinoma patients

Background

This study was performed to evaluate the impact of upgrade of radiotherapy system, including launch of intensity-modulated radiation therapy (IMRT), on the therapeutic outcomes.

Materials and methods

Patients with head and neck (H&N) squamous cell carcinoma (SCC) who underwent postoperative radiotherapy at our hospital between June 2009 and July 2019 were retrospectively reviewed. In July 2014, we converted the radiotherapy technique for these patients from a 3-dimensional conformal radiotherapy (3D-CRT) to IMRT, along with the adoption of a meticulous planning policy and a few advanced procedures, including online imaging guidance.

Results

A total of 136 patients (57 treated with the previous system and 79 treated with the upgraded system) were reviewed. There were significantly more patients with extracapsular extension in the upgraded-system group than the previous-system group (p = 0.0021). There were significantly fewer patients with ≥ Grade 2 acute and late adverse events in the upgraded-system group than the previous-system group. The differences in progression-free survival (PFS), distant metastasis-free survival (DFFS), locoregional progression-free survival (LRPFS), and overall survival (OS) between the two groups were not statistically significant (p = 0.8962, 0.9926, 0.6244, and 0.4827, respectively). Multivariate analysis revealed that the upgrade had neither positive nor negative impact on survival outcomes. Extracapsular extension was independently associated with decreased LRPFS and OS (p = 0.0499 and 0.0392, respectively).

Conclusions

The IMRT-centered upgrade was beneficial for the postoperative patients with H&N SCC, because survival outcomes were sustained with less toxicities.

Recurrence pattern with respect to two different dose fractionations in patients with locally advanced head and neck cancer treated with chemoradiation using image-guided volumetric arc therapy

BACKGROUND

Patients with head and neck cancer were treated with either 70 Gy in 35 fractions (Arm A) or 66 Gy in 30 fractions (Arm B).

MATERIALS AND METHODS

Total 168 patients of carcinoma oropharynx, larynx, and hypopharynx treated with radical chemoradiation in two Arm A versus B (65 vs. 103 patients).

RESULTS

With a median follow-up of 16 months (0-67), 2 year disease-free survival (DFS) and overall survival (OS) was 56.3% versus 62.1% (p = 0.64) and 44.5% versus 53.0% (p = 0.51) in Arm A versus B. Total 22 (33.8%) versus 28 (27.2%) failed locoregionally. Majority of failures were infield for both primary (17 vs. 23 cases) and nodes (13 vs. 12) in Arm A versus B. Ten (71.4%) vs. 10 (76.9%) had nodal failure in index nodal level only.

CONCLUSION

Commonly seen failure in head-neck radical chemoradiation is within infield high-risk volume, nodal failure being most common in index nodal level.

Patterns of recurrence after low-dose postoperative radiotherapy for head and neck squamous cell carcinoma

BACKGROUND

Postoperative chemoradiotherapy is recommended for patients with head and neck squamous cell carcinoma with positive margins or extracapsular extension at high risk of recurrence. However, high-dose radiotherapy in the head and neck region often causes severe acute and late radiation-related adversities. In our institution, the radiation dose has been relatively lower than that used in Western countries to reduce radiation-related toxicities. Therefore, in this study, we examined the treatment outcomes of low-dose postoperative chemoradiotherapy.

METHODS

The outcomes of 90 consecutive head and neck squamous cell carcinoma patients who received postoperative radiotherapy between June 2009 and December 2016 were retrospectively analyzed. All patients received postoperative three-dimensional conformal radiotherapy with or without concurrent systemic chemotherapy. The median patient age was 65 years. Concurrent chemoradiotherapy was administered at a total dose of 50.4 Gy in 28 fractions (daily fraction, 1.8 Gy). High-risk patients received 10.8 Gy of boost irradiation in six fractions. For radiotherapy alone, the irradiation dose was up to 54 Gy in 30 fractions and 64.8 Gy in 36 fractions for high-risk patients to increase the treatment intensity.

RESULTS

The median follow-up period was 40.5 months. The 3-year locoregional control and overall survival rates were 67.5% and 82.7%, respectively. A significantly higher proportion of patients with oral cavity carcinoma experienced locoregional failure (p = 0.004). The acute adverse events were mild, and the only late adverse event was grade 3 dysphagia (n = 3).

CONCLUSION

This study suggests that de-escalation of the postoperative radiation dose can potentially reduce the severe adverse events of irradiation in patients while ensuring its effectiveness. In patients with oral cavity carcinoma, it might be necessary to increase the radiation dose.

Chemoradiotherapy with high-dose cisplatin compared with weekly cisplatin for locally advanced head and neck squamous cell carcinoma

INTRODUCTION

Concurrent chemoradiotherapy (CRT) using high-dose cisplatin (HDC) is standard for patients with locally advanced head and neck squamous cell carcinoma (HNSCC); weekly cisplatin (WC) is an alternative. We aim to compare retrospectively the survival and disease control outcomes between these regimens in our institutional experience.

METHODS

Patients with stage III-IV HNSCC treated with definitive or postoperative CRT between 2012 and 2018 were identified. Patients were stratified by intent-to-treat CRT. Overall survival (OS) and disease-free survival (DFS) were generated and multivariable Cox models were performed.

RESULTS

193 patients were treated with concurrent HDC (n = 69), WC at 40 mg/m2 (WC40, n = 88) or WC at <40 mg/m2 (WC<40, n = 36). Treatment intent was definitive in 74% and adjuvant in 26%. Baseline differences included age, performance status and HPV status. Cumulative cisplatin dose ≥200 mg/m2 was achieved in 89% (HDC), 86% (WC40) and 25% (WC<40, P < 0.0001). For HDC, WC40 and WC<40, 2-year OS rates were 87%, 77%, 60% and 2-year DFS rates were 75%, 68% and 52%, respectively. Multivariable analysis revealed gender, performance status, primary site, T/N stage and chemotherapy as predictive of OS. Primary site, T/N stage and chemotherapy regimen were associated with DFS. Compared with HDC, no differences in locoregional control (LRC) or distant metastasis were observed between groups.

CONCLUSION

Concurrent HDC is associated with increased total cisplatin intensity, OS and DFS compared with weekly cisplatin regimens. LRC was not associated with chemotherapy regimen. HDC remains the standard of care; WC40 is a reasonable alternative that does not appear to sacrifice LRC.

Recommendations for postoperative radiotherapy in head & neck squamous cell carcinoma in the presence of flaps: A GORTEC internationally-reviewed HNCIG-endorsed consensus

INTRODUCTION

Head and neck reconstructive surgery using a flap is increasingly common. Best practices and outcomes for postoperative radiotherapy (poRT) with flaps have not been specified. We aimed to provide consensus recommendations to assist clinical decision-making highlighting areas of uncertainty in the presence of flaps.

MATERIAL AND METHODS

Radiation, medical, and surgical oncologists were assembled from GORTEC and internationally with the Head and Neck Cancer International Group (HNCIG). The consensus-building approach covered 59 topics across four domains: (1) identification of postoperative tissue changes on imaging for flap delineation, (2) understanding of tumor relapse risks and target volume definitions, (3) functional radiation-induced deterioration, (4) feasibility of flap avoidance.

RESULTS

Across the 4 domains, international consensus (median score ≥ 7/9) was achieved only for functional deterioration (73.3%); other consensus rates were 55.6% for poRT avoidance of flap structures, 41.2% for flap definition and 11.1% for tumor spread patterns. Radiation-induced flap fibrosis or atrophy and their functional impact was well recognized while flap necrosis was not, suggesting dose-volume adaptation for the former. Flap avoidance was recommended to minimize bone flap osteoradionecrosis but not soft-tissue toxicity. The need for identification (CT planning, fiducials, accurate operative report) and targeting of the junction area at risk between native tissues and flap was well recognized. Experts variably considered flaps as prone to tumor dissemination or not. Discrepancies in rating of 11 items among international reviewing participants are shown.

CONCLUSION

International GORTEC and HNCIG-endorsed recommendations were generated for the management of flaps in head and neck radiotherapy. Considerable knowledge gaps hinder further consensus, in particular with respect to tumor spread patterns.

Postoperative Concurrent Chemoradiotherapy Versus Radiotherapy Alone for Advanced Oral Cavity Cancer in the Era of Modern Radiation Techniques

Background/Purpose

Surgery followed by postoperative radiotherapy (RT) has been considered the standard treatment for oral cavity squamous cell carcinoma (OCSCC) of advanced stages or with adverse prognostic factors. In this study, we compared the outcomes in patients with OCSCC who received postoperative concurrent chemoradiotherapy (CCRT) or postoperative RT alone using modern RT techniques.

Methods

A total of 275 patients with OCSCC treated between 2002 and 2018 were retrospectively analyzed. Adverse prognostic factor was defined as extranodal extension (ENE), microscopically involved surgical margin, involvement of ≥2 lymph nodes, perineural disease, and/or lymphovascular invasion (LVI). In total, 148 patients (54%) received CCRT and 127 patients (46%) received RT alone. More patients in the CCRT group had N3 disease and stage IVB disease (46.6% vs. 10.2%, p<0.001), ENE (56.1% vs. 15.7%, p<0.001), LVI (28.4% vs. 13.4%, p=0.033).

Results

With a median follow-up of 40 (range, 5–203) months, there were no significant differences in the 5-year overall survival (OS) and PFS between treatment groups. In the subgroup analysis according to high risk, the concurrent use of chemotherapy showed significantly improved OS in patients with ENE (HR 0.39, p=0.003).

Conclusion

Our retrospective study showed that postoperative CCRT group had comparable survival outcomes to those in the RT alone group for advanced OCSCC in the era of modern RT techniques and indicated that concurrent chemotherapy should be administered to patients with ENE. Prospective randomized studies for confirmation are needed.

Metastasis-directed stereotactic body radiation therapy in the management of oligometastatic head and neck cancer

INTRODUCTION

Recently major efforts have been made to define the oligometastatic setting, but for head and neck cancer (HNC) limited data are available. We aimed to evaluate outcome of oligometastatic HNC treated with Stereotactic body radiotherapy (SBRT) as metastasis-directed therapy.

MATERIALS AND METHODS

We analyzed patients treated with SBRT on a maximum of five oligometastases from HNC, in up to two organs. Concomitant treatment was allowed. End points were toxicity, local control of treated metastases (LC), progression-free survival (PFS) and overall survival (OS).

RESULTS

48 consecutive patients and 71 lesions were treated. With a follow-up of 20.2 months, most common primary tumors were larynx (29.2%) and salivary glands (29.2%), while common site of metastases was lung (59.1%). Median dose was 48 Gy (21-75) in 3-8 fractions. Treatment was well tolerated, with two patients reporting mild pain and nausea. LC rates at 1 and 2 years were 83.1% and 70.2%. Previous local therapy (HR 4.97; p = 0.002), oligoprogression (HR 4.07; p = 0.031) and untreated metastases (HR 4.19; p = 0.027) were associated with worse LC. PFS at 1 and 2 years were 42.2% and 20.0%. Increasing age (HR 1.03; p = 0.010), non-adenoid cystic carcinoma (HR 2.57; p = 0.034) and non-lung metastases (HR 2.20; p = 0.025) were associated with worse PFS. One- and 2-years OS were 81.0% and 67.1%. Worse performance status (HR 2.91; p = 0.049), non-salivary primary (HR 19.9; p = 0.005), non-lung metastases (HR 2.96; p = 0.040) were correlated with inferior OS.

CONCLUSIONS

SBRT can be considered a safe metastasis-directed therapy in oligometastatic HNC. Efficacy of the treatment seems to be higher when administered upfront in the management of metastatic disease; however, selection of patients need to be improved due to the relevant risk of appearance of new metastatic site after SBRT.

Postoperative radiotherapy after flap reconstructive surgery in patients with head and neck cancer: A retrospective monocentric study with flap delineation to assess toxicity and relapse

PURPOSE

Flaps are increasingly used during reconstructive surgery of head and neck cancers to improve functional outcomes. There are no guidelines as to whether the whole flap or its anastomotic border should be included in the primary tumour target volume of postoperative radiotherapy to prevent local relapses. Relapse and toxicity rates can increase substantially if the whole flap received full dose. Our aim was to determine whether flaps were included in the primary tumour target volume and to report the patterns of relapse and toxicity.

MATERIALS AND METHODS

Consecutive patients in 2014 through 2016, with or without a flap, receiving postoperative radiotherapy were selected in a retrospective monocentric control study. Flaps were homogenously delineated blind to treating radiation oncologists using a flap-specific atlas. Tumour recurrence, acute and late toxicity were evaluated using univariate and propensity score analyses.

RESULTS

A hundred patients were included; 54 with a flap. Median flap volume included in the tumour volume was 80.9%. Twelve patients experienced local recurrences: six with a flap, among whom two within their flap (3.7%). Patients with flaps had larger median tumour volumes to be irradiated (25cm³ versus 58cm³, p<0.001) and higher acute/late toxicity rates (p<0.001) even after adjustment on biases (more advanced T stage, oral cavity, active smoking in patients with flaps). Locoregional recurrence and survival rates were similar between patients with/without a flap.

CONCLUSION

Recurrences within a flap were rare in this series when including the whole flap body in the 60Gy-clinical target volume but inclusion of the flap in the primary tumour target volume increased toxicity. Multicentric studies are warranted.

Missed radiation therapy sessions in first three weeks predict distant metastasis and less favorable outcomes in surgically treated patients with oral cavity squamous cell carcinoma

Background

We sought to investigate the prognostic impact of missed RT sessions in patients who had undergone surgery for oral cavity squamous cell carcinoma (OCSCC).

Methods

The study sample consisted of 905 patients with surgically treated OCSCC who fulfilled criteria of RT course ≤8 weeks. The study participants were divided into three groups based on the characteristics of missed RT, as follows: 1) early missed RT, 2) late missed RT, and 3) RT as scheduled.

Results

The 5-year overall survival (OS) rates in the early missed RT, late missed RT, and RT as scheduled groups were 53.0, 58.1, and 64.5%, respectively (p = 0.046). In multivariate analysis, early missed RT was independently associated with both OS (hazard ratio (HR) = 1.486; 95% confidence interval (CI): 1.122–1.966; p = 0.006) and the occurrence of distant metastasis (HR = 1.644; 95% CI: 1.047–2.583; p = 0.031).

Conclusion

Early missed RT was independently associated with a higher occurrence of distant metastasis and less favorable OS in patients who had undergone surgery for OCSCC.

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.

High-Dose Static and Dynamic Intensity-Modulated Radiotherapy Combined with Chemotherapy for Patients with Locally Advanced Nasopharyngeal Carcinoma Improves Survival and Reduces Brainstem Toxicity

BACKGROUND Intensity-modulated radiotherapy (IMRT) is the standard treatment for patients with nasopharyngeal cancer (NPC). However, the dose-volume criteria for adjacent anatomically normal organs at risk (OARs) remain controversial. The aim of this study was to evaluate the effects of higher than conventional doses of static and dynamic IMRT on the locoregional control of NPC, patient survival, and brainstem radiation toxicity. MATERIAL AND METHODS Patients (n=186) with stage III and stage IVa NPC underwent high-dose static and dynamic IMRT treatment (68-76.96 Gy) with or without chemotherapy for 34-57 days. Overall survival (OS), the presence of distant metastases, and brainstem toxicity were assessed. One-year, three-year, and five-year follow-up was performed. RESULTS High-dose IMRT alone or in combination with chemotherapy resulted in a 100% objective response rate and significantly improved OS rates, with one-year, three-year, and five-year OS rates of 94.1%, 89.8%, and 88.2%, respectively. The local recurrence rate (17.6%), and distant metastasis to the lung, liver, and bone (17.2%), and mortality (n=22) were reduced. Chemotherapy was the only factor that was significantly correlated with patient survival. Brainstem toxicity was reduced in patients treated with static IMRT (0.07%) and dynamic IMRT (0.08%). There were 26 additional factors that were not found to significantly affect brainstem toxicity. CONCLUSIONS High-dose static or dynamic IMRT combined with chemotherapy improved survival and reduces distal metastasis with a very low occurrence of brainstem toxicity in patients with locally advanced NPC. These findings might provide therapeutic guidance for clinicians when planning optimal dose-volume IMRT parameters.

How Histopathologic Tumor Extent and Patterns of Recurrence Data Inform the Development of Radiation Therapy Treatment Volumes in Solid Malignancies

The ability to deliver highly conformal radiation therapy using intensity-modulated radiation therapy and particle therapy provides for new opportunities to improve patient outcomes by reducing treatment-related morbidities following radiation therapy. By reducing the volume of normal tissue exposed to radiation therapy (RT), while also allowing for the opportunity to escalate the dose of RT delivered to the tumor, use of conformal RT delivery should also provide the possibility of expanding the therapeutic index of radiotherapy. However, the ability to safely and confidently deliver conformal RT is largely dependent on our ability to clearly define the clinical target volume for radiation therapy, which requires an in-depth knowledge of histopathologic extent of different tumor types, as well as patterns of recurrence data. In this article, we provide a comprehensive review of the histopathologic and radiographic data that provide the basis for evidence-based guidelines for clinical tumor volume delineation.

Comparisons of the clinical outcomes of different postoperative radiation strategies for treatment of head and neck squamous cell carcinoma

Purpose

We previously reported unfavorable locoregional control with limited field postoperative radiotherapy for head and neck squamous cell carcinoma patients and thus revised the strategy to cover the whole neck. Head and neck squamous cell carcinoma Patients' outcomes were retrospectively analyzed to compare the efficacy of two treatments.

Material and methods

Before 2010, the clinical target volume covered the tumor bed and/or involved the neck region. Since 2011, whole-neck irradiation was planned. Univariate analysis, multivariate analysis, and propensity score matching were performed. The study included 275 patients: 186 received limited field postoperative radiotherapy and 89 received whole-neck postoperative radiotherapy. The median follow-up time for the entire cohort was 40.8 months.

Results

In univariate analysis, the radiation strategy had no significant effect on overall survival and progression-free survival. In multivariate analysis, whole-neck postoperative radiotherapy was a favorable factor for overall survival, progression-free survival, and locoregional control. Propensity score matching resulted in a cohort comprising 118 well-matched patients evenly divided between the limited field postoperative radiotherapy and whole-neck postoperative radiotherapy groups. Whole-neck postoperative radiotherapy group achieved a significantly better 2-year overall survival (56.4% vs. 78.1%; P = 0.003), 2-year progression-free survival (34.7% vs. 59.8%; P = 0.009), and 2-year locoregional control (54.4% vs. 83.2%; P < 0.001). The limited field postoperative radiotherapy group developed significantly more locoregional recurrences both in-field (35.2% vs. 15.1%, P = 0.003) and out-of-field (25.0% vs. 0%, P < 0.001) in the matched-pair cohort.

Conclusion

Whole-neck postoperative radiotherapy is a more appropriate choice than limited field postoperative radiotherapy to improve overall survival, progression-free survival and locoregional control.

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

Background

We sought to identify spatial/dosimetric patterns of failure for oral cavity cancer patients receiving post-operative IMRT (PO-IMRT).

Methods

Two hundred eighty-nine OCC patients receiving PO-IMRT were retrospectively reviewed from 2000 to 2012. Diagnostic CT documenting recurrence (rCT) was co-registered with planning CT (pCT) using a validated deformable image registration software. Manually segmented recurrent gross disease (rGTV) was deformed to co-registered pCTs. Mapped rGTVs were compared dosimetrically to planned dose and spatially to planning target volumes using centroid-based approaches. Failures types were classified using combined spatial/dosimetric criteria: A (central high-dose), B (peripheral high-dose), C (central intermediate/low-dose), D (peripheral intermediate/low-dose), and E (extraneous-dose).

Results

Fifty-four patients with recurrence were analyzed; 26 local recurrence, 19 regional recurrence, and 9 both local and regional recurrence. Median time to recurrence was 4 months (range 0–71). Median rGTVs volume was 3.7 cm³ (IQR 1.4–10.6). For spatial and dosimetric analysis of the patterns of failure, 30 patients (55.5%) were classified as type A (central high-dose). Non-central high dose failures were distributed as follows: 2 (3.7%) type B, 10 (18.5%) type C, 1 (1.8%) type D, and 9 (16.7%) type E. Non-IMRT failure in the matching low-neck field was seen in two patients. No failures were noted at the IMRT-supraclavicular field match-line.

Conclusions

Approximately half of patients with local/regional failure had non-central high dose recurrence. Peripheral high dose misses were uncommon reflecting adequate delineation and dose delivery. Future strategies are needed to reduce types C and E failures.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-017-0868-y) contains supplementary material, which is available to authorized users.