Primary Intensity-modulated Radiotherapy Research Articles

Patterns and Prognosis of Local Recurrence of Nasopharyngeal Carcinoma after Intensity-modulated Radiotherapy.

Objective: To investigate the patterns of local failure and prognosis in patients with locally recurrent nasopharyngeal carcinoma (rNPC) after primary intensity-modulated radiotherapy (IMRT). Methods: The data of 298 patients with locally rNPC after IMRT were retrospectively analyzed. Magnetic resonance images of the initial and recurrent tumors were reviewed and, for patients with extra-nasopharyngeal local recurrence, the gross tumor volume of local recurrence was transferred to the original IMRT plan for dosimetry analysis. Significant prognostic factors for overall survival (OS) were selected by multivariate Cox regression analysis. Results: The commonest recurrence sites were the nasopharynx (93%, 277/298) and skull base (53.7%, 160/298). Of the 21 patients with extra-nasopharyngeal recurrence (19 cases valid), 12 had in-field failures, 4 had marginal failures, and 3 had out-field failures. The ethmoid sinus (57.1%, 4/7) and nasal cavity (28.6%, 2/7) were the most frequent sites of marginal and out-field failures. After median follow-up of 37 months, the 3-year and estimated 5-year OS rates were 57.3% and 41.7%, respectively. Multivariate analysis showed that age, recurrence interval, plasma Epstein-Barr virus (EBV) DNA level, and recurrent T stage were independent prognostic factors for OS. Conclusions: Local failure after IMRT occurs most commonly in the nasopharynx and skull base. In patients with extra-nasopharyngeal recurrence, in-field failure remains the main failure pattern, and marginal and out-field failures mainly occur in the ethmoid sinus and nasal cavity. Elder age, shorter recurrence interval, detectable plasma EBV DNA, and advanced recurrent T stage are negative predictors of OS in patients with rNPC.

Identification and Automated Delineation of Radioresistant Biological Tumor Volume in Nasopharyngeal Carcinoma Based on Magnetic Resonance Imaging Radiomics

Widespread use of intensity modulated radiotherapy (IMRT) has improved the tumor control rate of nasopharyngeal carcinoma (NPC). However, nearly 20% of the patients with local-advanced NPC would relapse after precise irradiation and 80% of the recurrent lesions occur within the high dose field, suggesting that there are radiation-resistant cancer cell subsets within the tumor. In this context, identification and contouring of radiation resistance region of NPC for dose escalation at primary IMRT could be advantageous. In this work, we proposed a two-step radiomics workflow to predict local relapse and the recurrent region of NPC before primary IMRT. In this single-center, retrospective study, pre-treatment magnetic resonance (MR) sequences of T1-weighted imaging (T1-w) and contrast-enhanced T1-weighted imaging (CET1-w) were collected from 800 patients of newly diagnosed and non-metastatic NPC between April 2009 and December 2015. The primary gross tumor volume (GTVp) of all patients and the actual recurrent lesion (GTVr) of patients who suffered from local recurrence were manually contoured for further analysis. A two-step complete radiomics workflow was designed to predict tumor recurrence and segment the region. First, least absolute shrinkage and selection operator (LASSO) was utilized for radiomics features selection of GTVp and support vector machine (SVM) was adopted to predict the recurrence. If the model predicts a recurrence, then the workflow utilizes an improved 3D U-Net to segment the recurrent region. Area under receiver operating characteristic curve (ROC-AUC) was used to evaluate the performance of tumor recurrence prediction, and Dice similarity coefficient (DSC) was used to assess the consistence between the actual and predicted GTVr. Of 800 NPC patients, 95 (11.9%) patients developed in-field local recurrence. For recurrence risk prediction, the SVM ensemble model (T1-w+CET1-w) was selected for further application with higher sensitivity. The average ROC-AUC, specificity, sensitivity of the SVM ensemble model in a 5-fold cross-validation and in the independent test set of 160 patients were 0.922, 0.922, 0.777 and 0.928, 0.915, 0.737, respectively. Moreover, for recurrent region segmentation, the multi-modality (T1-w+CET1-w) model was superior to the single-modality (T1-w or CET1-w) model. In an independent test set of 15 patients, the DSC, sensitivity and 95% Hausdorff Distance between actual and predicted GTVr was 0.549±0.176, 0.696±0.118 and 9.813±4.788 which was superior to 0.444±0.188, 0.497±0.218 and 12.047±5.361 of original 3D U-Net. The proposed two-step radiomics workflow showed a good performance in predicting tumor recurrence of NPC. The predicted location of the recurrence lesion was all accurate, but there was still a certain difference between the volume of the automated delineated and actual GTVr, which needed to be further optimized to be used as biological tumor volume.

Patterns and prognosis of regional recurrence in nasopharyngeal carcinoma after intensity-modulated radiotherapy.

We analyzed the patterns of lymph node (LN) failure and prognosis in patients with regional recurrent nasopharyngeal carcinoma (rNPC) alone after primary intensity-modulated radiotherapy (IMRT). A total of 175 patients who were treated with IMRT between 2010 and 2015 and who experienced regional recurrence alone were included. Recurrent LNs were re-located in the initial pretreatment imaging and IMRT plan and failures were classified as in-field or out-field based on target volume delineation. All patients underwent curative salvage treatment. Independent prognostic factors for overall survival (OS) were selected by multivariate Cox analysis. Level IIb (49.1%, 86/175) was the most frequent recurrence site, followed by level IIa (36%), level III (18.9%), level IVa (12%), the retropharyngeal region (8%), level Va (6.9%), and the parotid region (6.9%). A total of 264 recurrent LNs were recorded: 149 (56.4%) were classified as in-field failure with a prescribed dose ≥66 Gy, 60 (22.7%) with 60 to <66 Gy, 32 (12.1%) with 50 to <60 Gy, and 23 (8.7%) as an out-field failure, which mainly occurred in the parotid region and level Ib. After a median follow-up of 52.8months, the estimated 5-year OS rate was 66.9%. Multivariate analysis showed that age, plasma Epstein-Barr virus DNA level, extranodal extension, lower neck involvement, and parotid LN recurrence were independent prognostic factors of OS. In-field failure represented the main pattern of regional recurrence and out-field failure mainly occurred in the parotid gland and level Ib. Patients with regional rNPC alone had a good prognosis after salvage treatment.

Irradiation-induced nasopharyngeal necrosis (INN) in newly diagnosed nasopharyngeal carcinoma treated by intensity-modulated radiation therapy: clinical characteristics and the influence of treatment strategies

PurposeTo define the clinical characteristics of irradiation-induced nasopharyngeal necrosis (INN) after intensity-modulated radiotherapy (IMRT) and identify the influence of treatment strategies on INN in primary nasopharyngeal carcinoma (NPC) patients.Patients and methodsFrom 2008 to 2019, NPC patients pathologically diagnosed with INN after primary IMRT were reviewed. Those patients were matched with propensity scores for patients without INN in our center. The impact of treatment strategies on INN occurrence was assessed using univariate and multivariate logistic regression analysis.ResultsThe incidence rate of INN was 1.9% among the primary NPC population, and 53 patients with INN were enrolled. Headache and foul odor were the main symptoms, and 71.7% of cases had pseudomembrane during or at the end of radiotherapy. All patients were in early or middle stage INN, and no one presented with skull-based osteoradionecrosis. Then 212 non-INN patients were included based on propensity scores match. Overall survival (p = 0.248) and progression-free survival (p = 0.266) curves were similar between the INN and non-INN groups. Treatment strategies including combining chemotherapy or molecular targeted therapy with radiotherapy were not associated with INN occurrence, while boost dose (OR 7.360; 95% CI 2.301–23.547; p = 0.001) was a predictor factor for it. However, the optimal threshold for an accumulated dose to predict INN's occurrence was failed to determine.ConclusionIn the IMRT era, the severity of INN in primary NPC patients is lessened. This study showed that treatment strategies contributed little to develop INN, while the accumulated dose of radiation may relate to its occurrence.

Outcomes after primary intensity‐modulated radiation therapy for oropharyngeal squamous cell carcinoma at a New Zealand regional cancer centre: Impact of p16 status

The rising incidence of oropharyngeal squamous cell carcinoma (OPSCC) in New Zealand is due to an increase in the numbers of human papilloma virus (HPV)-associated OPSCC. We evaluated the impact of positive p16 immunohistochemistry, as a surrogate for HPV positivity, on OPSCC outcomes after primary intensity-modulated radiotherapy (IMRT) with or without concurrent chemotherapy. Retrospective review was undertaken of electronic medical records of 90 patients with OPSCC who received primary IMRT with or without chemotherapy between 2008 and mid-2015 at the Regional Cancer Centre, Waikato Hospital, Hamilton, New Zealand. Median age was 57.5years. Immunohistochemistry for p16 was positive in 53 (59%) OPSCC while 37 (41%) had negative or unknown p16 status. Median radiotherapy dose was 70Gy. Chemotherapy was administered to 78 (87%) patients, most receiving high-dose cisplatin. Nine patients had residual disease following treatment completion. Seven patients relapsed, and 26 died during the study period. Five patients with p16-positive OPSCC had persistent or recurrent disease. Actuarial 3-year locoregional control, disease-free survival, and overall survival for all patients were 80.7%, 74.7%, and 77.1%, respectively. Among p16-positive OPSCC patients, 3-year locoregional control, disease-free survival, and overall survival were 89.5%, 80.8%, and 90.9%, respectively. Outcomes after IMRT for OPSCC at Waikato Hospital are in line with the reported literature. Human papilloma virus-related OPSCC has better outcomes compared with patients with unknown or HPV-unrelated OPSCC. Trials are underway evaluating reduced intensity of treatment for HPV-related OPSCC.

Outcomes of intensity-modulated radiotherapy as primary treatment for oropharyngeal squamous cell carcinoma - a European singleinstitution analysis.

To analyse survival and toxicity outcomes in patients treated with primary intensity-modulated radiotherapy (IMRT) for oropharyngeal squamous cell carcinoma (OPSCC) in the era of routine human papilloma virus (HPV) testing. Single-institution case series. Tertiary Head and Neck Cancer Unit. A total of 186 patients received IMRT (+/- chemotherapy) for radical primary treatment of OPSCC between March 2010 and December 2013. HPV status was available for 88% of cases. Median radiation dose was 65 Gy in 30 daily fractions. 90% of stage III/IV patients received concurrent chemotherapy or cetuximab. Overall, disease-free and disease-specific survival; rates of late xerostomia and dysphagia. A total of 177 patients completed treatment (Stage I/II: 23; Stage III/IV: 154), with median follow-up of 26 months. Estimated 3-year overall survival (OS), disease-free survival (DFS) and disease-specific survival (DSS) rates were 77.2% (70.5-83.9), 72.3% (65.4-79.2) and 80.2% (74.1-86.3). Estimated 3-year OS, DFS and DSS for HPV-positive patients were 90.9% (85.2-96.6), 87.9% (81.4-94.4) and 91.8% (86.3-97.3). A previously identified risk stratification method was validated, showing improved OS for low-risk over high-risk patients (HR 0.09, P < 0.001). The 2-year feeding tube retention rate was 6%, and 2-year grade ≥2 xerostomia rate was 38% (23% if mean contralateral parotid dose <24 Gy). Outcomes with IMRT are favourable, particularly in the HPV-positive patient group. This data further supports the use of a previously described prognostication model that can be used to select patients for escalation/de-escalation clinical trials.

No benefit for regional control and survival by planned neck dissection in primary irradiated oropharyngeal cancer irrespective of p16 expression.

The aim of the study was to assess regional control and survival in primary irradiated oropharyngeal cancer patients with advanced neck disease (≥cN2a) receiving planned neck dissection (PND) irrespective of the nodal response compared to salvage neck dissection (SND) in case of regional persistence or reccurence in relation to tumoral p16 overexpression. 96 consecutive patients treated at the University Hospital of Zurich, Switzerland were included. Tissue microarray-based scoring of p16 expression was obtained. 5years overall (OS) and disease-specific survival (DSS) in the PND and SND cohort were 70 vs. 57% (p=0.20) and 80 vs. 65% (p=0.14), respectively. Regional control in PND and SND achieved 95 vs. 87% (p=0.29), respectively. There was no statistically significant impact of neck treatment (PND vs. SND) on regional control or survival among patients with p16-negative tumors (5years OS 59 vs. 50%, p=0.66; 5years DSS 59 vs. 57%, p=0.89) nor among patients with p16-positive tumors (5years OS 84 vs. 67%, p=0.21; 5years DSS 95 vs. 81%, p=0.24). The type of neck dissection after primary intensity-modulated radiotherapy (IMRT) had no impact on regional control and survival even in human papillomavirus (HPV)-associated disease. Therefore we are convinced that based on the accuracy of newer diagnostic modalities the surveillance of a radiologically negative neck after primary chemoradiation (CRT) is oncologically safe irrespective of p16 expression of the tumor.

Rectal toxicity after intensity modulated radiotherapy for prostate cancer: Which rectal dose volume constraints should we use?

BackgroundTo define rectal dose volume constraints (DVC) to prevent ⩾grade2 late rectal toxicity (LRT) after intensity modulated radiotherapy (IMRT) for prostate cancer (PC). Material and methodsSix hundred thirty-seven PC patients were treated with primary (prostate median dose: 78Gy) or postoperative (prostatic bed median dose: 74Gy (adjuvant)–76Gy (salvage)) IMRTwhile restricting the rectal dose to 76Gy, 72Gy and 74Gy respectively. The impact of patient characteristics and rectal volume parameters on ⩾grade2 LRT was determined. DVC were defined to estimate the 5% and 10% risk of developing ⩾grade2 LRT. ResultsThe 5-year probability of being free from ⩾grade2 LRT, non-rectal blood loss and persisting symptoms is 88.8% (95% CI: 85.8–91.1%), 93.4% (95% CI: 91.0–95.1%) and 94.3% (95% CI: 92.0–95.9%) respectively.There was no correlation with patient characteristics. All volume parameters, except rectal volume receiving ⩾70Gy (R70), were significantly correlated with ⩾grade2 LRT. To avoid 10% and 5% risk of ⩾grade2 LRT following DVC were derived: R40, R50, R60 and R65 <64–35%, 52–22%, 38–14% and 5% respectively. ConclusionApplying existing rectal volume constraints resulted in a 5-year estimated risk of developing late ⩾grade2 LRT of 11.2%. New rectal DVC for primary and postoperative IMRT planning of PC patients are proposed. A prospective evaluation is needed.

Impact of p16, p53, smoking, and alcohol on survival in patients with oropharyngeal squamous cell carcinoma treated with primary intensity‐modulated chemoradiation

Analysis of the impact of risk factors on survival in patients with oropharyngeal squamous cell carcinoma (OPSCC) treated by primary intensity-modulated radiotherapy (IMRT). One hundred forty patients were included with tissue microarray (TMA) construction and immunohistochemical analysis in 124 patients (87%). Survival analysis of patients classified into 3 risk categories according to an algorithm based on p16, smoking, T classification, and N classification revealed significant differences with a low, intermediate, and high-risk group. There was a significant impact of p53 expression as surrogate marker for smoking on outcome. In multivariate analysis, p16-positivity was a positive predictor and alcohol as well as N classification was a negative predictor for survival. The algorithm was modified based on alcohol instead of smoking with even more significant differences between the groups. A risk model based on multiple factors instead of p16 as single marker can define different risk groups to select patients for treatment deintensification in future prospective clinical trials.

Radiotherapy Treatment Plans With RapidArc for Prostate Cancer Involving Seminal Vesicles and Lymph Nodes

Dosimetric results and treatment delivery efficiency of RapidArc plans to those of conventional intensity-modulated radiotherapy (IMRT) plans were compared using the Eclipse treatment planning system for high-risk prostate cancer. This study included 10 patients. The primary planning target volume (PTV(P)) contained prostate, seminal vesicles, and pelvic lymph nodes with a margin. The boost PTV (PTV(B)) contained prostate and seminal vesicles with a margin. The total prescription dose was 75.6 Gy (46.8 Gy to PTV(P) and an additional 28.8 Gy to PTV(B); 1.8 Gy/fraction). Three plans were generated for each PTV: Multiple-field IMRT, one-arc RapidArc (1ARC), and two-arc RapidArc (2ARC). In the primary IMRT with PTV(P), average mean doses to bladder, rectum and small bowel were lower by 5.9%, 7.7% and 4.3%, respectively, than in the primary 1ARC and by 3.6%, 4.8% and 3.1%, respectively, than in the primary 2ARC. In the boost IMRT with PTV(B), average mean doses to bladder and rectum were lower by 2.6% and 4.8% than with the boost 1ARC and were higher by 0.6% and 0.2% than with the boost 2ARC. Integral doses were 7% to 9% higher with RapidArc than with IMRT for both primary and boost plans. Treatment delivery time was reduced by 2-7 minutes using RapidArc. For PTVs including prostate, seminal vesicles, and lymph nodes, IMRT performed better in dose sparing for bladder, rectum, and small bowel than did RapidArc. For PTVs including prostate and seminal vesicles, RapidArc with two arcs provided plans comparable to those for IMRT. The treatment delivery is more efficient with RapidArc.

Pre-segmented 2-Step IMRT with subsequent direct machine parameter optimisation – a planning study

BackgroundModern intensity modulated radiotherapy (IMRT) mostly uses iterative optimisation methods. The integration of machine parameters into the optimisation process of step and shoot leaf positions has been shown to be successful. For IMRT segmentation algorithms based on the analysis of the geometrical structure of the planning target volumes (PTV) and the organs at risk (OAR), the potential of such procedures has not yet been fully explored. In this work, 2-Step IMRT was combined with subsequent direct machine parameter optimisation (DMPO-Raysearch Laboratories, Sweden) to investigate this potential.MethodsIn a planning study DMPO on a commercial planning system was compared with manual primary 2-Step IMRT segment generation followed by DMPO optimisation. 15 clinical cases and the ESTRO Quasimodo phantom were employed. Both the same number of optimisation steps and the same set of objective values were used. The plans were compared with a clinical DMPO reference plan and a traditional IMRT plan based on fluence optimisation and consequent segmentation. The composite objective value (the weighted sum of quadratic deviations of the objective values and the related points in the dose volume histogram) was used as a measure for the plan quality. Additionally, a more extended set of parameters was used for the breast cases to compare the plans.ResultsThe plans with segments pre-defined with 2-Step IMRT were slightly superior to DMPO alone in the majority of cases. The composite objective value tended to be even lower for a smaller number of segments. The total number of monitor units was slightly higher than for the DMPO-plans. Traditional IMRT fluence optimisation with subsequent segmentation could not compete.Conclusion2-Step IMRT segmentation is suitable as starting point for further DMPO optimisation and, in general, results in less complex plans which are equal or superior to plans generated by DMPO alone.

A Clinical Study of Dose-Escalation Following Primary Intensity Modulated Radiotherapy for Nasopharyngeal Carcinoma

A Clinical Study of Dose-Escalation Following Primary Intensity Modulated Radiotherapy for Nasopharyngeal Carcinoma

4000 ORAL Update of the results of the Dutch multicenter randomized phase III trial comparing 68 Gy of external beam radiotherapy with 78 Gy for localized prostate cancer

To define rectal dose volume constraints (DVC) to prevent ⩾grade2 late rectal toxicity (LRT) after intensity modulated radiotherapy (IMRT) for prostate cancer (PC).Six hundred thirty-seven PC patients were treated with primary (prostate median dose: 78 Gy) or postoperative (prostatic bed median dose: 74 Gy (adjuvant)–76 Gy (salvage)) IMRT while restricting the rectal dose to 76 Gy, 72 Gy and 74 Gy respectively. The impact of patient characteristics and rectal volume parameters on ⩾grade2 LRT was determined. DVC were defined to estimate the 5% and 10% risk of developing ⩾grade2 LRT.The 5-year probability of being free from ⩾grade2 LRT, non-rectal blood loss and persisting symptoms is 88.8% (95% CI: 85.8–91.1%), 93.4% (95% CI: 91.0–95.1%) and 94.3% (95% CI: 92.0–95.9%) respectively.There was no correlation with patient characteristics. All volume parameters, except rectal volume receiving ⩾70 Gy (R70), were significantly correlated with ⩾grade2 LRT. To avoid 10% and 5% risk of ⩾grade2 LRT following DVC were derived: R40, R50, R60 and R65 <64–35%, 52–22%, 38–14% and 5% respectively.Applying existing rectal volume constraints resulted in a 5-year estimated risk of developing late ⩾grade2 LRT of 11.2%. New rectal DVC for primary and postoperative IMRT planning of PC patients are proposed. A prospective evaluation is needed.

Recurrences near base of skull after IMRT for head-and-neck cancer: implications for target delineation in high neck and for parotid gland sparing

Purpose Locoregional (LR) failures near the base of the skull, and their relationships to the targets in the high neck, were examined in a series of patients who underwent intensity-modulated radiotherapy (IMRT) for head-and-neck cancer. Methods and materials Between 1994 and 2002, 133 patients with non–nasopharyngeal head-and-neck squamous cell carcinoma completed a course of curative, parotid-sparing RT. Treatment was delivered until 1996 with conformal three-dimensional techniques and thereafter with multisegmental static IMRT. Of the 133 patients, 80 had oropharyngeal, 27 oral cavity, 12 hypopharyngeal, 11 laryngeal, and 3 unknown primary cancer. The AJCC stage was I in 1, II in 6, III in 26, IVA in 83, and IVB in 12; cancer was recurrent in 5. Sixty patients received primary and 73 postoperative IMRT. 86% of patients ( n = 115) had ipsilateral neck metastasis. In all patients, the contralateral neck was clinically node negative but was judged to be at high risk of subclinical disease. Delineation of the superior-most extent of the nodal targets was consistent and corresponded with Rouviere's observations. In the contralateral clinically node-negative neck, the uppermost Level II nodal target was the subdigastric (SD) nodes. To ensure coverage, the uppermost clinical target volume was delineated at the axial CT image in which the posterior belly of the digastric muscle crossed the jugular vein. In the ipsilateral neck, which was node positive in most patients, the uppermost Level II clinical target volume was delineated through the base of the skull. The uppermost retropharyngeal (RP) nodal target was delineated at the level of the top of the C1 vertebral body, accommodating Rouviere's description of the location of the lateral RP nodes. The dose prescription was 70 Gy for the primary planning target volumes (PTVs); 64 Gy and 60 Gy for PTV of the postoperative beds with and without extracapsular extension, respectively; and 50–54 Gy for PTVs of nonoperated subclinical disease, at 1.8–2.0 Gy fractions. In-field or marginal recurrences were defined as those occurring when >95% or 20–95% of the recurrence volume, respectively, had received >95% of the prescribed dose. Results At a median follow-up of 32 months (range, 6–107 months), 21 patients (16%) had locoregional recurrence. Seventeen recurrences were in-field and four were marginal. The most prevalent nodal recurrence was in Level II bilaterally, where all failures were in-field. In-field failures were observed in the ipsilateral high neck cranial to the SD nodes (all in initially node-positive neck). No recurrences occurred in the contralateral high neck, cranial to the SD nodes, which was not included in the targets. The 95% confidence interval for the risk of recurrence in that region was 0–2.7%. Three RP nodal failures were observed; two were marginal, occurring ipsilateral and contralateral to the primary tumors, and centered cranial to the top of C1. After these recurrences, the RP nodal clinical target volumes were delineated bilaterally through the base of skull, without subsequent RP recurrence. These target delineation guidelines allowed the achievement of a mean contralateral parotid dose of ≤26 Gy (found previously to preserve salivary output significantly) in 82% of the patients. The 3-year actuarial LR recurrence-free survival rate of primary and postoperative IMRT patients was similar (81% and 84%, respectively). Oropharyngeal cancer patients had the greatest LR recurrence-free survival rate (94%, p <0.001). No statistically significant differences were found in the dose delivered to the PTVs or the in-field recurrence volume between patients who had or did not have LR failure. Conclusion These results suggest that when the contralateral node-negative side of the neck has a high risk of subclinical metastasis, it is adequate to include the SD nodes as the cranial-most Level II nodal target in non–nasopharyngeal head-and-neck cancer. In the node-positive side of the neck, this nodal level should be delineated more cranially. The RP nodal targets should be delineated bilaterally and should extend to the base of the skull, rather than to the top of C1. These guidelines allowed substantial sparing of the contralateral parotid gland. The results of this series validate a consensus for target delineation adopted recently by cooperative radiotherapy groups.