Comparison of two different IMRT planning techniques in the treatment of nasopharyngeal carcinoma. Effect on parotid gland radiation doses

Dosimetric comparison between Intensity Modulated Radiation Therapy (IMRT) vs dual arc Volumetric Arc Therapy (VMAT) for nasopharyngeal cancer (NPC): Systematic review and meta-analysis

BACKGROUND AND PURPOSE

Previous non-randomised studies comparing dosimetric outcomes between advanced techniques such as IMRT and VMAT reported conflicting findings. We thus sought to perform a systematic review and meta-analysis to consolidate the findings of these studies.

MATERIALS AND METHODS

We searched PUBMED and EMBASE for eligible studies from their time of inception to 10 March 2022. A random effects model was used to estimate the pooled mean differences (MDs) and their 95% confidence intervals(CIs) for target volume coverage, organ-at-risk(OAR) doses, monitor units(MUs) and treatment delivery times. We also performed a subgroup analysis to evaluate if different treatment planning systems (TPS) (Eclipse, Monaco and Pinnacle) used affected the pooled mean differences.

RESULTS

A total of 17 studies (383 patients) were eligible to be included. The pooled results showed that dual arc VMAT reduced D2% of PTV (MD=0.71Gy,95%CI=0.14-1.27,P=0.01), mean left cochlea dose (MD=2.6Gy,95%CI=0.03-5.16,P=0.05), mean right cochlea dose (MD=3.4Gy,95%CI=0.7-6.1,P=0.01), MUs (MD=554.9,95%CI=245.8-863.9,P=0.0004), treatment delivery times (MD=6.7mins,95%CI=4.5-8.9,P<0.0001) and integral dose (MD=0.97Gy,95%CI=0.28-1.67,P=0.006). None of the other indices were significantly better for the IMRT plans. The subgroup analysis showed that the integral dose was significantly lower only for Eclipse (MD=0.88Gy, 95%CI=0.14-1.63, P=0.02). The total MUs was significantly lower only for Eclipse (MD=1035.2, 95%CI=624.6-1445.9, P<0.0001) and Pinnacle (MD=293, 95%CI=15.6-570.5, P=0.04). Similarly, delivery time was also significantly lower only for Eclipse (MD=6.1mins, 95%CI=5.7-6.5, P<0.0001) and Pinnacle (MD=4.9mins, 95%CI=2.6-7.2, P<0.0001). The subgroup analysis however showed that target coverage was superior for the IMRT plans for both Pinnacle (MD=0.48Gy, 95%CI=0.31-0.66, P<0.0001) and Monaco (MD=0.12Gy, 95%CI=0.07-0.17, P<0.0001).

CONCLUSION

Dual-arc VMAT plans improved OAR doses, MUs and treatment times as compared to IMRT plans. The different TPS used may modify dosimetric outcomes.

Evaluation of target autocrop function in nasopharyngeal carcinoma SIB IMRT plan

A new target autocrop function was introduced in the Varian Eclipse™ treatment planning software (version 15.5 above) (Lohynská in Klin Onkol 33(4):288-294, 2020). The study aimed to evaluate this new target autocrop impact on nasopharyngeal carcinoma (NPC) plan quality and delivery efficiency. Randomly 66 approved NPC simultaneous integrated boost (SIB) intensity-modulated radiation therapy (IMRT) treatment plans were retrospectively studied. The manual cropping-based plans served as reference and were designed using sliding-window IMRT. Reference plans were re-optimized with identical plan parameters following the institutional clinical protocol, except for the redundant optimization objective of the manual cropping targets deleted. Additionally, each target within 5 mm of another had one minimum objective at 100% volume and one maximum objective at 0% volume for the autocrop plans. Plan quality was assessed based on selected parameters, including TCP (tumor control probability), NTCP (normal tissue complication probability), conformality index (CI), homogeneity index (HI), and dose-volume characteristics. Additionally, the delivery efficiency, the total plan treatment time defined as a sum of monitor units (MUs) for each treated field, and delivery accuracy, γ passing rate of treatment plan quality assurance (QA) also were compared. Both the manual cropping plans and the autocrop plans could be approved by an experienced oncologist. Overall, the autocrop plans could provide approximately a 13% reduction in linac MU while maintaining comparable plan quality, radiobiological ranking, and accuracy to the manual cropping plans. The new target autocrop tip facilitated the SIB IMRT plans for nasopharyngeal cancer patients. The autocrop could guarantee the quality and delivery accuracy of the radiotherapy plan and improved the planning efficiency, treatment efficiency, and reduced machine wear and tear. It was a promising tool for optimal plan selection for NPC SIB IMRT.

Quality of life and survival outcome for patients with nasopharyngeal carcinoma treated by volumetric-modulated arc therapy versus intensity-modulated radiotherapy

BACKGROUND

To evaluate the longitudinal changes of quality of life (QoL) and survival in patients with nasopharyngeal carcinoma (NPC) treated by volumetric-modulated arc therapy (VMAT) versus intensity-modulated radiotherapy (IMRT).

METHODS

One hundred and forty non-distant metastatic NPC patients treated by VMAT (n = 66) or IMRT (n = 74) with simultaneously integrated boost between March 2013 and December 2015 at a single institute were analyzed. QoL was prospectively assessed by the EORTC QLQ-C30 and HN35 questionnaires at the four time points: before RT, RT 42.4 Gy (20 fractions), and 3, 12 months after RT.

RESULTS

The 3-year locoregional relapse-free survival, distant metastasis-free survival, failure-free survival, and overall survival rates were 96.6, 89.4, 86.1%, and 87.4 for the VMAT group, respectively, compared with 91.4, 90.0, 79.8, and 91.3% for the IMRT group (p value > 0.05). The pattern of QoL changes was similar between the VMAT and IMRT group. No statistically or clinically significant difference in all the QoL scales was observed between VMAT and IMRT group at each time point. Compared to before RT, we observed statistically (p<0.05) and clinically (difference of mean scores≧10) better outcome in global QoL and social functioning, but worse head and neck symptomatic outcome in swallowing, taste/smell, opening mouth, dry mouth, and sticky saliva at the time point of 1 year after RT for both groups.

CONCLUSION

The study provides the evidence that the tumor control, survival and changes of QoL is compatible for NPC patients treated by VMAT versus IMRT.

Superiority of intensity-modulated radiation therapy in nasopharyngeal carcinoma with skull-base invasion

PURPOSE

To compare the clinical results and functional outcomes between two-dimensional conventional radiation therapy (2DRT) and intensity-modulated radiation therapy (IMRT) in nasopharyngeal carcinoma (NPC) with skull-base invasion.

METHODS

A total of 1258 patients were subclassified into two groups: mild skull-base invasion group (792; 63%) and severe skull-base invasion group (466; 37%). Patients were pair matched (1:1 ratio) using six clinical factors into 2DRT or IMRT groups. The Kaplan-Meier method and Cox regression model were performed to assess overall survival (OS), disease-free survival (DFS), locoregional relapse-free survival (LRRFS) and distant metastasis-free survival (DMFS). Toxicities were evaluated.

RESULTS

IMRT significantly improved four-year OS compared with 2DRT (65.6% vs. 81.8%, P = 0.000), DFS (57.3% vs. 73.3%, P = 0.000) and LRRFS (76.5% vs. 87.5%, P = 0.003) in NPC with severe skull-base invasion, but similar results were observed in patients with mild skull-base invasion (P > 0.05). In patients with severe invasion, radiation therapy techniques were found to be an independent prognostic factor for OS (HR = 0.457, P = 0.000), DFS (HR = 0.547, P = 0.000) and LRRFS (HR = 0.503, P = 0.004). IMRT was associated with better OS. In subgroups analysis, IMRT group also had a better survival in OS, DFS (P < 0.05 for all rates) for patients received concurrent chemotherapy and sequential chemotherapy compared to 2DRT in the severe invasion group. The IMRT group displayed lower incidence of mucositis, xerostomia, trismus (< 1 cm) and temporal lobe necrosis than the 2DRT group.

CONCLUSIONS

IMRT significantly improved patient survival compared with 2DRT in NPC patients with severe skull-base invasion, but a similar survival rate was noted in mild invasion patients. Chemotherapy can improve survival in NPC patients with severe invasion. Among the two therapies, IMRT significantly decreased therapy-related toxicity.

Cetuximab in combination with chemoradiotherapy for nasopharyngeal carcinoma: A meta-analysis

AIMS AND OBJECTIVES

The aims and objectives of this study are to investigate the efficacy and safety of chemoradiotherapy (CCRT) with or without cetuximab in nasopharyngeal carcinoma (NPC).

METHODS

We searched the Cochrane Library, PubMed, Embase, CNKI, VIP, Chinese biomedicine literature database, and WANFANG database for relevant articles. The methodological quality of included studies was evaluated, and data were analyzed using RevMan 5.0 software.

RESULTS

Ten relevant articles (783 patients) were identified. The results were complete response rate; the response rate was significantly better in the cetuximab plus CCRT (C225+CCRT) group than the CCRT group. The partial response and 3-year-overall survival rates were not significantly different between the two groups. Regarding adverse effects, myelosuppression was observed in the CRRT group and the C225+CCRT group; the main toxicity was mucositis and rash, but no significant statistical difference was observed.

CONCLUSION

The combination of cetuximab and CCRT was more effective for NPC than CCRT alone and had no serious side effects.

Concurrent chemoradiotherapy by simultaneously integrated boost volumetric-modulated arc therapy for nasopharyngeal carcinoma-toxicity/quality of life and survival

BACKGROUND

To investigate the toxicity, changes of quality of life (QOL), and survival for patients with nasopharyngeal cancer (NPC) treated by concurrent chemoradiotherapy (CCRT) with simultaneously integrated boost volumetric-modulated arc therapy (SIB-VMAT).

METHODS

A total of 68 NPC patients treated by CCRT with SIB-VMAT technique were collected. QOL was longitudinally assessed by the EORTC QLQ-C30 and HN35 questionnaires at the 4 time points: baseline, 42.4 Gy (20 fractions), and 3, 12 months after CCRT.

RESULTS

The 4-year locoregional relapse free, distant metastasis free, failure free, and overall survival rates were 97.0%, 86.4%, 82.0%, and 88.1%, respectively. The 4-year cumulative incidence rate of late toxicities with grade 3 or more was 3.0%. One year after CCRT, most QOL scales, except some oral related symptoms, recovered to baseline level.

CONCLUSION

CCRT with SIB-VMAT produces excellent locoregional control, few severe late toxicity, and good general health status for NPC patients.

Slug inhibition increases radiosensitivity of nasopharyngeal carcinoma cell line C666-1

Slug is associated with the radioresistance of nasopharyngeal carcinoma (NPC) and the main current approach of treatment for NPC is radiotherapy. Hence, the aim of the current study was to determine the effect of Slug silencing on the radiosensitivity of NPC cells. Lentiviral-mediated transfection of Slug RNA interference (RNAi) in NPC cell line C666-1 was performed in vitro. Following Slug inhibition, its expression was detected using western blotting. A clonogenic survival assay and flow cytometry were then performed to evaluate the clonogenic cell survival, cell cycle distribution and apoptosis of C666-1 cells following irradiation. The results indicated that Slug RNAi decreased cell proliferation, and increased cell apoptosis and G₀/G₁ arrest. Thus, lentiviral-mediated transfection of Slug RNAi enhanced the radiosensitivity of the NPC cell line C666-1, and Slug may therefore be a potential target to improve radiotherapy in treatment of NPC and reduce the radioresistance of NPC.

SmartArc-based volumetric modulated arc therapy can improve the middle ear, vestibule and cochlea sparing for locoregionally advanced nasopharyngeal carcinoma: a dosimetric comparison with step-and-shoot intensity-modulated radiotherapy

OBJECTIVE

Radiation-induced sensorineural hearing loss is a common complication after radiotherapy in patients with nasopharyngeal carcinoma (NPC) that significantly affects their quality of life. The goal of this study was to compare SmartArc-based volumetric modulated arc therapy (VMAT-S) with step-and-shoot intensity-modulated radiation therapy (IMRT) for patients with locoregionally advanced NPC with regard to the sparing effect on middle ear, vestibule and cochlea.

METHODS

20 patients with non-metastatic Stage III or IV NPC were selected to have planning with VMAT-S and IMRT [using Philips Pinnacle Planning System (Philips, Fitchburg, WI) for Varian accelerator] for dosimetric comparison. Mean middle ears, vestibule and cochlea doses for the two planning techniques were compared using a paired t-test. Target coverage and dose homogeneity were evaluated by calculating conformity index (CI) and homogeneity index (HI) values.

RESULTS

VMAT-S had significantly improved homogeneity and conformity compared with IMRT. Mean HI of planning target volume of gross tumour volume (PGTV) was better with VMAT-S (1.05 ± 0.02) than IMRT (1.09 ± 0.03) (p < 0.001). Mean CI of PGTV is also better with VMAT-S (0.59 ± 0.12) than IMRT (0.54 ± 0.12) (p < 0.001). Mean doses to the left cochleas were 43.8 ± 3.6 and 47.8 ± 4.0 (p < 0.001) for VMAT-S and IMRT plans, respectively. Mean doses to the right cochleas were 42.7 ± 4.7 and 47.6 ± 5.4 (p < 0.001) for VMAT-S and IMRT plans, respectively. VMAT-S also significantly reduced the mean doses to middle ears (p < 0.001 for both) and vestibule (p < 0.001 for both).

CONCLUSION

Our results indicate that VMAT-S provides better sparing of hearing apparatus in locoregionally advanced NPC.

ADVANCES IN KNOWLEDGE

VMAT-S can improve the middle ear, vestibule and cochlea sparing in patients with locoregionally advanced NPC.

Clinical and dosimetric evaluation of RapidArc versus standard sliding window IMRT in the treatment of head and neck cancer

BACKGROUND

Several planning studies have already proven the substantial dosimetric advantages of RapidArc (RA) over standard intensity-modulated radiotherapy. We retrospectively compared RapidArc and standard sliding window IMRT (swIMRT) in locally advanced head and neck cancer, looking both at dosimetrics as well as toxicity and outcome.

METHODS

CT datasets of 78 patients treated with swIMRT and 79 patients treated with RA were included. To compare the resulting dose distributions, the dose-volume parameters were evaluated for the planning target volumes (PTVs), clinical target volumes (CTVs), and organs at risk (OARs), and the number of MU were calculated. Acute toxicity was assessed by the Common Toxicity Criteria version 3.0.

RESULTS

PTV coverage with the 95% isodose was slightly better for RA. Dose distribution has proven to be significantly more homogenous with RA and led to a reduction of 62% in MU with better OAR sparing. As for toxicity, more grade 3 mucositis and dysphagia was observed for swIMRT, though we observed more grade 3 dermatitis for RA.

CONCLUSION

In our retrospective analysis, RA had better target coverage and better sparing of the OAR. Overall, the grade of acute toxicity was lower for RA than for swIMRT for the same types of tumor locations, except for the grade of dermatitis.

Concurrent chemoradiotherapy in locoregionally advanced nasopharyngeal carcinoma: treatment outcomes of a prospective, multicentric clinical study

BACKGROUND AND PURPOSE

To evaluate long-term outcome in locoregionally advanced nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy.

MATERIAL AND METHODS

Between January 2006 and August 2008, 249 patients with stage III-IVb NPC were treated by IMRT plus concurrent chemotherapy in this multicenter prospective study.

RESULTS

With a mean follow-up of 54.1 months, the 5-year actuarial rates of overall survival (OS), local recurrence-free survival (LRFS), regional recurrence-free survival (RRFS), and distant metastasis-free survival (DMFS) were 78.4%, 86.8%, 88.4%, 78.0%, respectively. There were 29 local recurrences, 25 regional recurrences and 52 distant metastases, respectively. Distant metastasis is the main cause of treatment failure. N-stage was an independent prognostic factor for LRFS, RRFS, DMFS and OS. Acute toxicity ⩾grade III mainly consisted of mucositis (34.9%), neutropenia (11.2%), xerostomia (5.6%), and dermatitis (5.2%). The main documented late toxicity was xerostomia, and the severity of xerostomia decreased over time. At 24 months after treatment, 13.2% of patients had grade 2 xerostomia, and none had grade 3 or 4 xerostomia.

CONCLUSIONS

IMRT with concurrent cisplatin chemotherapy resulted in encouraging rates of local and distant control and overall survival with acceptable rates of acute and limited rates of late toxicity in patients with locoregionally advanced NPC. Distant metastasis remained the main cause of failure. More effective systemic therapy should be explored for patients with advanced N-stage.

Intensity-modulated radiotherapy for stage IVA/IVB nasopharyngeal carcinoma: clinical outcomes and patterns of failure in an endemic area in China

PURPOSE

The purpose of this study was to analyze the mode of relapse patterns and survival of 209 patients with stage IVA and IVB nasopharyngeal carcinoma (NPC).

PATIENTS AND MATERIALS

A total of 209 patients who underwent magnetic resonance imaging (MRI) and were subsequently histologically diagnosed with nondisseminated stage IV NPC received intensity-modulated radiotherapy (IMRT) as their primary treatment and were included in this retrospective study.

RESULTS

Median follow-up time was 65 months (range, 3-108 months). The 5-year overall survival (OS), disease-free survival (DFS), local recurrence-free survival (LRFS), locoregional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS) rates for patients with stage IVA and stage IVB NPC were 72.7 vs. 60.0 % (p = 0.319), 62.9 vs. 51.3 % (p = 0.070), 82.9 vs. 93.1 % (p = 0.070), 82.9 vs. 82.9 % (p = 0.897), 76.4 vs. 58.5 % (p = 0.003), respectively. Age older than 44 years was found to be a statistically significant adverse independent prognostic factor for OS. Patients with advanced N status had worse OS, DFS, and DMFS rates. Patients with a primary gross tumor volume (GTV-P) ≥ 55.11 ml had worse OS, DFS, and LRRFS rates.

CONCLUSION

The results of treating stage IVA NPC with IMRT were excellent. Distant metastasis remains the most difficult treatment challenge for patients with stage IVA and IVB NPC, and more effective systemic chemotherapy should be explored.

MRI-detected skull-base invasion: prognostic value and therapeutic implication in intensity-modulated radiotherapy treatment for nasopharyngeal carcinoma

PURPOSE

With advances in imaging and radiotherapy, the prognostic value of skull-base invasion in nasopharyngeal carcinoma (NPC) needs to be reassessed. We aimed to define a classification system and evaluate the prognostic value of the classification of magnetic resonance imaging (MRI)-detected skull-base invasion in NPC treated with intensity-modulated radiotherapy (IMRT).

PATIENTS AND MATERIALS

We retrospectively reviewed 749 patients who underwent MRI and were subsequently histologically diagnosed with nondisseminated NPC and treated with IMRT.

RESULTS

MRI-detected skull-base invasion was not found to be an independent prognostic factor for overall survival (OS), distant metastasis-free survival (DMFS), local relapse-free survival (LRFS), or disease-free survival (DFS; p > 0.05 for all). Skull-base invasion was classified according to the incidence of each site (type I sites inside pharyngobasilar fascia and clivus vs. type II sites outside pharyngobasilar fascia). The 5-year OS, DMFS, LRFS, and DFS rates in the classification of skull-base invasion in NPC were 83 vs. 67 %, 85 vs.75 %, 95 vs. 88 %, and 76 vs. 62 %, respectively (p < 0.05 for all). Multivariate analysis indicated the classification of skull-base invasion was an independent prognostic factor.

CONCLUSION

MRI-detected skull-base invasion is not an independent prognostic factor in patients with NPC treated with IMRT. However, classification according to the site of invasion has prognostic value. Therefore, patients with various subclassifications of stage T3 disease may receive treatment with different intensities; however, further studies are warranted to prove this.

Beam path toxicity in candidate organs-at-risk: assessment of radiation emetogenesis for patients receiving head and neck intensity modulated radiotherapy

BACKGROUND

To investigate potential dose-response relationship between radiation-associated nausea and vomiting (RANV) reported during radiotherapy and candidate nausea/vomiting-associated regions of interest (CNV-ROIs) in head and neck (HNC) squamous cell carcinomas.

METHODS AND MATERIAL

A total of 130 patients treated with IMRT with squamous cell carcinomas of head and neck were evaluated. For each patient, CNV-ROIs were segmented manually on planning CT images. Clinical on-treatment RANV data were reconstructed by a review of the records for all patients. Dosimetric data parameters were recorded from dose-volume histograms. Nausea and vomiting reports were concatenated as a single binary "Any N/V" variable, and as a "CTC-V2+" variable.

RESULTS

The mean dose to CNV-ROIs was higher for patients experiencing RANV events. For patients receiving IMRT alone, a dose-response effect was observed with varying degrees of magnitude, at a statistically significant level for the area postrema, brainstem, dorsal vagal complex, medulla oblongata, solitary nucleus, oropharyngeal mucosa and whole brain CNV-ROIs.

CONCLUSION

RANV is a common therapy-related morbidity facing patients receiving HNC radiotherapy, and, for those receiving radiotherapy-alone, is associated with modifiable dose to specific CNS structures.

Radiation recall dermatitis after docetaxel chemotherapy. Treatment by antioxidant ointment

Radiation recall dermatitis (RRD) is an acute skin toxicity caused by different anticancer or antibiotic drugs within a former completely healed irradiation field. Predictive factors for RRD are not known and its mechanisms are not completely understood. A case of RRD induced by docetaxel and successfully treated by an antioxidant ointment (Mapisal(®)) is presented here. Such an ointment might be useful not only in RRD therapy, but also in the treatment of high-grade dermatitis induced by radiotherapy and thus may contribute to the improvement of patients' quality of life and to the scheduled completion of cancer therapies.