Target Coverage in Head and Neck Cancer Treated with Intensity-Modulated Radiotherapy: A Comparison between Conventional and Conformal Techniques

To segment or not to segment the PTV in SIB-VMAT of head-and-neck cancer: a dosimetric comparison with relevance to clinical practice

Aim:

This study aimed to evaluate and compare simultaneous integrated boost-based volumetric modulated arc therapy (SIB-VMAT) of head-and-neck plans optimised using segmented and non-segmented intermediate-risk target volumes.

Materials and methods:

CT data of 20 patients with locally advanced laryngeal cancer treated with radical chemoradiation were included retrospectively. Both segmented [planning target volume (PTV) IR!] and non-segmented PTV (PTV IR) volumes were created for the intermediate-risk volume. Correspondingly, two VMAT plans were generated for every CT dataset. Dosimetry parameters obtained from cumulative dose volume histogram and the quality indices such as conformity and homogeneity indices were evaluated for both plans and were statistically analysed.

Results:

Maximum dose of PTV IR! was observed to be higher in the non-segmented plans (7281·45 versus 7075·75 cGy) and was statistically significant (p = 0·002). Homogeneity index (HI) of PTV IR! in segmented plans fared better compared to non-segmented plans (0·1 versus 0·12, p = 0·01). All other dosimetry parameters were found to be similar in both plans.

Conclusion:

This study shows that using segmented volumes for planning will lead to more homogenous plans with regard to intermediate- and low-risk volumes, especially under controlled settings.

Modelling Radiation-Induced Salivary Dysfunction during IMRT and Chemotherapy for Nasopharyngeal Cancer Patients

BACKGROUND

Radiation-induced xerostomia is one of the most prevalent adverse effects of head and neck cancer treatment, and it could seriously affect patients' qualities of life. It results primarily from damage to the salivary glands, but its onset and severity may also be influenced by other patient-, tumour-, and treatment-related factors. We aimed to build and validate a predictive model for acute salivary dysfunction (aSD) for locally advanced nasopharyngeal carcinoma (NPC) patients by combining clinical and dosimetric factors.

METHODS

A cohort of consecutive NPC patients treated curatively with IMRT and chemotherapy at 70 Gy (2-2.12 Gy/fraction) were utilised. Parotid glands (cPG, considered as a single organ) and the oral cavity (OC) were selected as organs-at-risk. The aSD was assessed at baseline and weekly during RT, grade ≥ 2 aSD chosen as the endpoint. Dose-volume histograms were reduced to the Equivalent Uniform Dose (EUD). Dosimetric and clinical/treatment features selected via LASSO were inserted into a multivariable logistic model. Model validation was performed on two cohorts of patients with prospective aSD, and scored using the same schedule/scale: a cohort (NPC_V) of NPC patients (as in model training), and a cohort of mixed non-NPC head and neck cancer patients (HNC_V).

RESULTS

The model training cohort included 132 patients. Grade ≥ 2 aSD was reported in 90 patients (68.2%). Analyses resulted in a 4-variables model, including doses of up to 98% of cPG (cPG_D98%, OR = 1.04), EUD to OC with n = 0.05 (OR = 1.11), age (OR = 1.08, 5-year interval) and smoking history (OR = 1.37, yes vs. no). Calibration was good. The NPC_V cohort included 38 patients, with aSD scored in 34 patients (89.5%); the HNC_V cohort included 93 patients, 77 with aSD (92.8%). As a general observation, the incidence of aSD was significantly different in the training and validation populations (p = 0.01), thus impairing calibration-in-the-large. At the same time, the effect size for the two dosimetric factors was confirmed. Discrimination was also satisfactory in both cohorts: AUC was 0.73, and 0.68 in NPC_V and HNC_V cohorts, respectively.

CONCLUSION

cPG D98% and the high doses received by small OC volumes were found to have the most impact on grade ≥ 2 acute xerostomia, with age and smoking history acting as a dose-modifying factor. Findings on the development population were confirmed in two prospectively collected validation populations.

Prognostic role of primary tumor, nodal neck, and retropharyngeal GTVs for unresectable sinonasal cancers treated with IMRT and chemotherapy

Background:

We evaluated the prognostic role of gross tumor volumes (GTVs) of primary tumor and positive lymph nodes on overall survival (OS) and progression-free survival (PFS) in locally advanced unresectable sinonasal cancer (SNC) treated with definitive intensity-modulated radiotherapy (IMRT) with or without chemotherapy.

Methods:

Primary tumor GTV (GTV-T), pathologic neck nodes GTV (GTV-N), and positive retropharyngeal nodes GTV (GTV-RPN) of 34 patients with epithelial nonglandular SNC receiving IMRT with or without chemotherapy were retrospectively measured. The GTV variables were analyzed in relation with OS and PFS. Survival curves were estimated using the Kaplan-Meier method and compared with the log-rank test. We also estimated the crude cumulative incidence of locoregional relapses only. The optimal volume cutoff value was determined using an outcome-oriented method among the observed values.

Results:

GTV-T was significantly associated with decreased OS ( P=0.003) and PFS ( P=0.003). Moreover, patients with disease total volumes (GTV) smaller than 149.44 cm³ had better OS and PFS than patients with higher volumes ( P<0.0001 for both). Neck nodal metastasis impacted on OS and PFS ( P=0.030 and P=0.033, respectively), but GTV-N did not ( P=0.961; P=0.958). Retropharyngeal nodes metastasis was not associated with prognosis (OS: P=0.400; PFS: P=0.104). When GTV-RPN was added to GTV-N (GTV-TN), a relation with PFS ( P=0.041) and a trend toward significance for OS ( P=0.075) were found.

Conclusions:

Our results show that tumor volume is a powerful predictor of outcome in SNC. This could be useful to identify patients with worse prognosis deserving different treatment strategies.

Preemptive treatment with Xonrid®, a medical device to reduce radiation induced dermatitis in head and neck cancer patients receiving curative treatment: a pilot study

PURPOSE

The purpose of this study was to investigate efficacy, safety and tolerability of Xonrid®, a new medical device, in preventing radiation dermatitis associated with head and neck cancer (HNC) radiotherapy (RT).

METHODS

In this monocentric, prospective pilot study, adult consecutive HNC patients who were planned to receive curative RT with or without chemotherapy were enrolled. Patients were instructed to apply Xonrid® on the irradiated area during treatment continuing until 2 weeks after the completion of RT or the development of severe skin toxicity. Toxicity was assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0 scale. The patient reported outcome measures included the Skindex-16 questionnaire and patient satisfaction. Skin reflectance spectra were analyzed to objectively evaluate dermatitis.

RESULTS

In total, 41 subjects were enrolled (30 males, median age 60 years). No skin adverse events were recorded either in the skin area where the product was applied or in the nearby skin over the entire period of administration. At the end of RT, nine patients (22%) presented G1, 31 (76%) G2, and one patient (2%) G3 skin toxicity (after 5 weeks). Seven and 20 patients reached skin maximum toxicity at the fourth week and after the seventh week, respectively. An increasing trend of median spectrophotometry scores along with skin toxicity grades was observed. A correlation between Skindex-16 scores and skin toxicity grade during treatment was found.

CONCLUSIONS

Our study results suggest that Xonrid® is well tolerated, safe, and effective in minimizing and delaying high-grade radiation dermatitis in HNC patients.

Image Guidance-Based Target Volume Margin Expansion in IMRT of Head and Neck Cancer

This study quantifies the setup uncertainties to optimize the planning target volume (PTV) margin based on daily image guidance, its dosimetric impact, and radiobiological implication for intensity-modulated radiation therapy (IMRT) in head and neck cancer. Ten patients were retrospectively chosen who had been treated with IMRT and with daily image-guided radiation therapy (IGRT). The daily setup errors of the 10 patients from on-board imaging for the entire treatment were analyzed. Planning target volumes were generated by expanding the clinical target volumes (CTVs) with 0 to 10 mm margins. The IMRT plans with the same dose-volume constraints were created in an Eclipse treatment planning system. The effect of volume expansion was analyzed with biological indices such as tumor control probability, normal tissue complication probability (NTCP), and equivalent uniform dose. Analysis of 906 daily setup corrections using daily IGRT showed that 98% of the daily setups are within ± 5 mm. The relative increase in PTV-CTV volume from 0 to 10 mm margins provides nearly 4-fold volume increase and is linearly related to monitor unit (MU). The increase in MU is about 5%/mm margin increase. The relative increase in NTCP of parotids from 5 to 10 mm margins is 3.2 ± 1.15. Increase in PTV margin increases extra tissue volume with a corresponding increase in MU for treatment and NTCP values. Even a small margin increase (eg, 1 mm) may result in increase of more than 20% in relative extra volume and 15% in NTCP value of organs at risk (OARs). With image guidance, the setup uncertainty could be achieved within ± 5 mm for 98% of the treatments, and a margin <5 mm for PTV may seem desirable to reduce the extra tissue irradiated, but at the expense of a more demanding setup accuracy.

Comparison of 3D confromal radiotherapy and intensity modulated radiotherapy with or without simultaneous integrated boost during concurrent chemoradiation for locally advanced head and neck cancers

OBJECTIVE

Radiotherapy techniques have evolved from 3D conformal radiotherapy (3D-CRT) to intensity modulated radiotherapy (IMRT) where boost fields are delivered either sequentially (IMRTseq) or with a simultaneous integrated boost (IMRT+SIB). Our goal was to compare the outcomes of patients treated with IMRT+SIB to traditional standards.

METHODS

We analyzed the efficacy and toxicity of patients treated with concurrent chemoradiation using 3D-CRT, IMRTseq or IMRT+SIB. Between 1993 and 2012, 379 patients with non-metastatic Stage III-IV head and neck squamous cell cancer were treated with concurrent chemoradiation using 3D-CRT (n = 125), IMRTseq (n = 120) and IMRT+SIB (n = 134).

RESULTS

Patients treated with any technique had similar rates of 2y local control, 2y regional control, 2y progression free survival and 2y overall survival. Patients treated with IMRT+SIB had lower rates acute toxicity according to Grade 3 or greater mucositis (3D-CRT: 44.0% vs. IMRTseq: 36.7% vs. IMRT+SIB: 22.4%; P<.0001), dermatitis (3D-CRT: 44.0% vs. IMRTseq: 20.0% vs. IMRT+SIB: 7.5%; P<.0001) and feeding tube placement during radiotherapy (3D-CRT: 80.0% vs. IMRTseq: 50.8% vs. IMRT+SIB: 44.0%; P<.0001) as well as late toxicity as measured by feeding tube use (P<.0001) and tracheostomy use (P<.0001). On multivariate analysis, IMRT+SIB predicted for less mucositis, dermatitis and feeding tube use compared to 3D-CRT and for less dermatitis compared to IMRTseq.

CONCLUSIONS

Compared to 3D-CRT and IMRTseq, IMRT+SIB provided similar outcomes and potentially less toxicity indicating it is a feasible technique for chemoradiation in locally advanced head and neck cancer.

Radiobiological basis and clinical results of the simultaneous integrated boost (SIB) in intensity modulated radiotherapy (IMRT) for head and neck cancer: A review

The simultaneous integrated boost (SIB)-IMRT technique allows the simultaneous delivery of different dose levels to different target volumes within a single treatment fraction. The most significant aspect associated with SIB-IMRT is related to the fractionation strategy, concerning two time-dose parameters: (1) the shortening of the overall treatment time (OTT); (2) the increase of fraction size (FS) to the boost volume. The SIB-IMRT technique represents, therefore, a new way to investigate the accelerated fractionation in definitive treatment of head and neck (H&N) cancers. The aims of this paper are the following: (1) to briefly review the influence of OTT and FS on H&N tumors and on acutely and late responding normal tissues; (2) to review the results of clinical studies of accelerated radiotherapy not employing IMRT in H&N cancer; (3) to review the clinical experiences of the SIB-IMRT technique and to compare the different SIB regimes in terms of radiobiological efficacy.

Further improvement in outcomes of nasopharyngeal carcinoma with optimized radiotherapy and induction plus concomitant chemotherapy: an update of the Milan experience

PURPOSE

To report the outcome of a consecutive series of patients with nonmetastatic nasopharyngeal carcinoma (NPC), focusing on the impact of treatment-related factors.

METHODS AND MATERIALS

Between 2000 and 2006, 87 patients with NPC were treated with either conventional (two- or three-dimensional) radiotherapy (RT) or with intensity-modulated RT (IMRT). Of these patients, 81 (93%) received either concomitant CHT (24%) or both induction and concomitant chemotherapy (CHT) (69%). Stage was III in 36% and IV in 39% of patients. Outcomes in this study population were compared with those in the previous series of 171 patients treated during 1990 to 1999.

RESULTS

With a median follow-up of 46 months, actuarial rates at 3 years were the following: local control, 96%; local-regional control, 93%; distant control (DC), 90%; disease-free survival (DFS), 82%; overall survival, 90%. In Stage III to IV patients, distant control at 3 years was 56% in patients treated with concomitant CHT only and 92% in patients treated with both induction and concomitant CHT (p = 0.014). At multivariate analysis, histology, N-stage, RT technique, and total RT dose had the strongest independent impact on DFS (p < 0.05). Induction CHT had a borderline effect on DC (p = 0.07). Most dosimetric statistics were improved in the group of patients treated with IMRT compared with conventional 3D technique. All outcome endpoints were substantially better in the study population compared with those in the previous series.

CONCLUSIONS

Outcome of NPC has further improved in the study period compared with the previous decade, with a significant effect of RT technique optimization. The impact of induction CHT remains to be demonstrated in controlled trials.