Gold coated contact lens-type ocular in vivo dosimeter (CLOD) for monitoring of low dose in computed tomography: A Monte Carlo study

PURPOSE

This study reports a sensitivity enhancement of gold-coated contact lens-type ocular in vivo dosimeters (CLODs) for low-dose measurements in computed tomography (CT).

METHODS

Monte Carlo (MC) simulations were conducted to evaluate the dose enhancement from the gold (Au) layers on the CLODs. The human eye and CLODs were modeled, and the X-ray tube voltages were defined as 80, 120, and 140 kVp. The thickness of the Au layer attached to a CLOD ranged from 100 nm to 10 μm. The thickness of the active layer ranged from 20 to 140 μm. The dose ratio between the active layer of the Au-coated CLOD and a CLOD without a layer, i.e., the dose enhancement factor (DEF), was calculated.

RESULTS

The DEFs of the first 20-μm thick active layer of the 5-μm thick Au-coated CLOD were 18.4, 19.7, 20.2 at 80, 120, and 140 kVp, respectively. The DEFs decreased as the thickness of the active layer increased. The DEFs of 100-nm to 5-μm thick Au layers increased from 1.7 to 5.4 for 120-kVp X-ray tube voltage when the thickness of the active layer was 140 μm.

CONCLUSIONS

The MC results presented a higher sensitivity of Au-coated CLODs (∼20-times higher than that of CLODs without a gold layer). Au-coated CLODs can be applied to an evaluation of very low doses (a few cGy) delivered to patients during CT imaging.

Extended application of a CT-based artificial intelligence prognostication model in patients with primary lung cancer undergoing stereotactic ablative radiotherapy

BACKGROUND AND PURPOSE

To validate a computed tomography (CT)-based deep learning prognostication model, originally developed for a surgical cohort, in patients with primary lung cancer undergoing stereotactic ablative radiotherapy (SABR).

MATERIALS AND METHODS

This retrospective study identified patients with clinical stage T1-2N0M0 lung cancer treated with SABR between 2013 and 2018. The outcomes were local recurrence-free survival (LRFS), disease-free survival (DFS), and overall survival (OS). The discrimination performance of the model, which extracted a quantitative score of cumulative risk for an adverse event up to 900 days, was evaluated using time-dependent receiver operating characteristic curve analysis. Multivariable Cox regression was performed to investigate the independent prognostic value of the model output adjusting for clinical factors including age, sex, smoking status, and clinical T category.

RESULTS

In total, 135 patients (median age, 78 years; 101 men; 78 [57.8%] adenocarcinomas and 57 [42.2%] squamous cell carcinomas) were evaluated. Most patients (117/135) were treated with 48-60 Gy in four fractions. Median biologically effective dose was 150.0 Gy (interquartile range, 126.9, 150.0 Gy). For LRFS, the area under the curve (AUC) was 0.72 (95% confidence interval [CI]: 0.58, 0.87). The AUCs were 0.70 (95% CI: 0.60, 0.81) for DFS and 0.66 (95% CI: 0.54, 0.77) for OS. Model output was associated with LRFS (adjusted hazard ratio [HR], 1.043; 95% CI: 1.003, 1.085; P = 0.04), DFS (adjusted HR, 1.03; 95% CI: 1.01, 1.05; P = 0.008), and OS (adjusted HR, 1.025; 95% CI: 1.002, 1.047; P = 0.03).

CONCLUSION

This study showed external validity and transportability of the CT-based deep learning prognostication model for radiotherapy candidates.

Retropharyngeal lymph node-sparing radiotherapy in patients with oropharyngeal carcinoma

Purpose

In radiotherapy for head and neck cancer, it is crucial to define the appropriate treatment volume to determine treatment outcome and toxicity. We examined the feasibility of omitting elective high retropharyngeal lymph node (RPLN) irradiation in patients with oropharyngeal cancer.

Materials and Methods

We performed a retrospective review of 189 patients with oropharyngeal squamous cell carcinoma who were treated with definitive or postoperative radiation therapy between 2009 and 2016. Of them, 144 (76.2%) underwent ipsilateral RPLN irradiation up to the superior border of the C1 vertebral body, while the other 45 (23.8%) were irradiated up to the transverse process of the C1 vertebra. High RPLN-treated and spared group were propensity matched based on key clinical variables.

Results

During the follow-up period, only three patients (one in the high RPLN-treated group and two in the high RPLN-spared group) developed RPLN recurrence. There were no significant between-group differences in 5-year locoregional failure-free survival (82.8% vs. 90.6%; p = 0.14), distant metastasis-free survival (93.1% vs. 93.3%; p = 0.98) and RPLN failure-free survival (99.3% vs. 95.0%; p = 0.09). In the matched groups, high RPLN-spared patients received a lower mean ipsilateral parotid gland dose (mean, 20.8 Gy vs. 29.9 Gy; p < 0.001) and had a lower incidence of chronic xerostomia (grade 0, 43.5% vs. 13.0%; p = 0.023) at 1 year after radiotherapy compared with high RPLN-treated patients.

Conclusion

Omission of ipsilateral high RPLN irradiation seems safe, and reduces the incidence of chronic xerostomia in patients with oropharyngeal squamous cell carcinoma.

Who Will Benefit from Charged-Particle Therapy?

Charged-particle therapy (CPT) such as proton beam therapy (PBT) and carbon-ion radiotherapy (CIRT) exhibit substantial physical and biological advantages compared to conventional photon radiotherapy. As it can reduce the amount of radiation irradiated in the normal organ, CPT has been mainly applied to pediatric cancer and radioresistent tumors in the eloquent area. Although there is a possibility of greater benefits, high set-up cost and dearth of high level of clinical evidence hinder wide applications of CPT. This review aims to present recent clinical results of PBT and CIRT in selected diseases focusing on possible indications of CPT. We also discussed how clinical studies are conducted to increase the number of patients who can benefit from CPT despite its high cost.

Technological Advances in Charged-Particle Therapy

Charted-particle therapy (CPT) benefits cancer patients by localizing doses in the tumor volume while minimizing the doses delivered to normal tissue through its unique physical and biological characteristics. The world's first CPT applied on humans was proton beam therapy (PBT), which was performed in the mid-1950s. Among heavy ions, carbon ions showed the most favorable biological characteristics for the treatment of cancer patients. Carbon ions show coincidence between the Bragg peak and maximum value of relative biological effectiveness. In addition, they show low oxygen enhancement ratios. Therefore, carbon-ion radiotherapy (CIRT) has become mainstream in the treatment of cancer patients using heavy ions. CIRT was first performed in 1977 at the Lawrence Berkeley Laboratory. The CPT technology has advanced in the intervening decades, enabling the use of rotating gantry, beam delivery with fast pencil-beam scanning, image-guided particle therapy, and intensity-modulated particle therapy. As a result, as of 2019, a total of 222,425 and 34,138 patients with cancer had been treated globally with PBT and CIRT, respectively. For more effective and efficient CPT, many groups are currently conducting further studies worldwide. This review summarizes recent technological advances that facilitate clinical use of CPT.

Radiotherapy Versus Surgery in Early-Stage HPV-positive Oropharyngeal Cancer

Purpose

To compare the outcomes of primary radiotherapy (RT) versus surgery in early-stage human papilloma virus-positive oropharyngeal squamous cell carcinoma (hpv+OPC), and investigate the preoperative clinical factors that can predict the requirement for postoperative adjuvant treatment.

Materials and Methods

This multicenter study included 166 patients with AJCC 8th edition-Stages I-II hpv+OPC. Sixty (36.1%) and 106 (63.9%) patients underwent primary (CC)RT and surgery, respectively. Seventy-eight (73.6%) patients in the surgery group received postoperative (CC)RT.

Results

With a median follow-up of 45.6 months for survivors, the 2-year overall survival (OS), progression-free survival (PFS), and locoregional control (LC) for radiotherapy/surgery were 97.8%/96.4%, 91.1%/92.0%, and 92.9%/93.3%, respectively. In multivariate analyses, patients with synchronous radiologic extranodal extension and conglomeration (ENEcong) of metastatic LNs showed significantly poorer OS (p=0.047), PFS (p=0.001) and LC (p=0.003). In patients undergoing primary surgery, two or more clinically positive LN metastases (OR, 5.15; p=0.004) and LN metastases with ENEcong (OR, 3.75; p=0.009) were predictors of postoperative chemoradiotherapy. No patient in the primary radiotherapy group demonstrated late severe toxicity whereas 3 (2.8%), 1 (0.9%), and 1 (0.9%) patient in the surgery group showed grade 3 dysphagia, grade 3 xerostomia, and fatal oral cavity bleeding.

Conclusion

We found no differences in OS, PFS, and LC between upfront radiotherapy and surgery in stage I-II hpv+OPC which warrants comparison through a prospective trial in the treatment de-escalation era. However, most early-stage hpv+OPC patients undergoing surgery received adjuvant (CC)RT. Pretreatment LN findings were prognostic and predictive for adjuvant treatment.

The effect of comprehensive oral care program on oral health and quality of life in patients undergoing radiotherapy for head and neck cancer: A quasi-experimental case-control study

OBJECTIVES

The purpose of this study is to investigate the effect of the comprehensive oral care program on oral health status and symptoms in head and neck cancer (HNC) patients undergoing radiotherapy.

METHODS

This was a quasi-experimental study using a non-equivalent control group in non-synchronized design. All participants including control and experimental group were asked for the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire H&N35 (EORTC QLQ-H&N35) and given an oral health education 4 times at baseline, immediate postradiotherapy, 3 months after radiotherapy, and 6 months after radiotherapy. In each visit except for final, the experimental group was given fluoride varnish application and fluoride mouth rinsing solution for daily use. Oral health examination for dental caries, plaque score (PS), bleeding on probing (BOP), and salivary flow rate was performed in baseline and 6 months after radiotherapy. Statistical analyses were done by paired t-tests and mixed ANCOVA repeated-measures analysis.

RESULTS

From November 1, 2013 to October 31, 2015, a total 61 patients undergoing radiotherapy for HNC cancer were enrolled (30 in control and 31 in experimental groups). Decrease in salivary flow rate was comparable between 2 groups. Dental caries increased in control group (P = .006); PS and BOP were decreased in experimental group (P < .001 and .004, respectively). Experimental group showed lower swallowing, speech problems, and less sexuality scores in EORTC QLQ-H&N35 than control group.

CONCLUSION

We found improvement in oral health and the quality of life in HNC patients with comprehensive oral care intervention by dental professionals. Communicating and cooperating between the healthcare and dental professionals is needed to raise the quality of health care services for HNC patients receiving radiotherapy.

Correlation between 3D scanner image and MRI for tracking volume changes in head and neck cancer patients

Introduction

We investigated the correlation between optical surface imaging using a three‐dimensional (3D) scanner and magnetic resonance imaging (MRI) for suggesting feasibility in the clinical process of tracking volume changes in head and neck patients during radiation treatment.

Methods

Ten patients were divided into two groups depending on the location of their tumor (i.e., right or left side). With weekly imaging data, the change in volume based on MRI was evaluated during the treatment course. Four volumes of interest (VOIs) were calculated on the 3D surface image of the facial and cervical areas using an optical 3D scanner, and the correlation between volumetric parameters were analyzed.

Results

The target volume changed significantly overall for both groups. The changes parotid volume reduced by up to 3.8% and 28.0% for groups A (right side) and B (left side), respectively. In Group A, VOI 1 on the facial area and VOI 3 on the cervical area decreased gradually during the treatment course by up to 3.3% and 10.7%, respectively. In Group B, only VOI 4 decreased gradually during the treatment course and reduced by up to 9.2%. In group A, the change in target volume correlated strongly with right‐side parotid, VOI 1, and VOI 3, respectively. The parotid also showed strong correlations with VOIs (P < 0.01). The weight loss was strongly correlated with either PTV or parotid without statistical significance (P > 0.05). In group B (left side), the change in target volume correlated strongly with each volumetric parameter, including weight loss. For individual patient, PTV showed more correlation with VOIs on the cervical area than VOIs on the facial area.

Conclusions

An optical 3D scanner can be applied to track changes in volume without radiation exposure during treatment and the optical surface image correlated with MRI.

Role of concurrent chemoradiation on locally advanced unresectable adenoid cystic carcinoma

BACKGROUND/AIMS

Adenoid cystic carcinoma (ACC) is a rare salivary gland tumor characterized by indolence, with a high rate of local recurrence and distant metastasis. This study aimed to investigate the effect of concurrent chemoradiation (CCRT) on locally advanced unresectable ACC.

METHODS

We retrospectively analyzed clinical data from 10 patients with pathologically confirmed ACC of the head and neck who received CCRT with cisplatin in Seoul National University Hospital between 2013 and 2018.

RESULTS

Ten patients with unresectable disease at the time of diagnosis or with positive margins after surgical resection received CCRT with weekly cisplatin. Eight patients (80%) achieved complete remission, of which three later developed distant metastases without local relapse; one patient developed distant metastasis and local relapse. Two patient achieved partial remission without progression. Patients experienced several toxicities, including dry mouth, radiation dermatitis, nausea, and salivary gland inflammation of mostly grade 1 to 2. Only one patient showed grade 3 oral mucositis. Median relapse-free survival was 34.5 months (95% confidence interval, 22.8 months to not reached).

CONCLUSION

CCRT with cisplatin is effective for local control of ACC with manageable toxicity and may be an effective treatment option for locally advanced unresectable ACC.

Correlation of the gamma passing rates with the differences in the dose-volumetric parameters between the original VMAT plans and actual deliveries of the VMAT plans

Purpose

The aim of this study was to investigate the correlations of the gamma passing rates (GPR) with the dose-volumetric parameter changes between the original volumetric modulated arc therapy (VMAT) plans and the actual deliveries of the VMAT plans (DV errors). We compared the correlations of the TrueBeam STx system to those of a C-series linac.

Methods

A total of 20 patients with head and neck (H&N) cancer were retrospectively selected for this study. For each patient, two VMAT plans with the TrueBeam STx and Trilogy (C-series linac) systems were generated under similar modulation degrees. Both the global and local GPRs with various gamma criteria (3%/3 mm, 2%/2 mm, 2%/1 mm, 1%/2 mm, and 1%/1 mm) were acquired with the 2D dose distributions measured using the MapCHECK2 detector array. During VMAT deliveries, the linac log files of the multi-leaf collimator positions, gantry angles, and delivered monitor units were acquired. The DV errors were calculated with the 3D dose distributions reconstructed using the log files. Subsequently, Spearman’s rank correlation coefficients (r_s) and the corresponding p values were calculated between the GPRs and the DV errors.

Results

For the Trilogy system, the r_s values with p < 0.05 showed weak correlations between the GPRs and the DV errors (r_s<0.4) whereas for the TrueBeam STx system, moderate or strong correlations were observed (r_s≥0.4). The DV errors in the V_20Gy of the left parotid gland and those in the mean dose of the right parotid gland showed strong correlations (always with r_s > 0.6) with the GPRs with gamma criteria except 3%/3 mm. As the GPRs increased, the DV errors decreased.

Conclusion

The GPRs showed strong correlations with some of the DV errors for the VMAT plans for H&N cancer with the TrueBeam STx system.

Heart substructural dosimetric parameters and risk of cardiac events after definitive chemoradiotherapy for stage III non-small cell lung cancer

INTRODUCTION

We evaluated the incidence of cardiac events after chemoradiotherapy in patients with stage III non-small cell lung cancer (NSCLC) based on baseline cardiovascular risk and the heart substructures' radiation dose.

METHODS

From 2008 to 2018, the cardiac events of 258 patients with stage III NSCLC who received definitive chemoradiotherapy were reviewed. The 10-year cardiovascular risk was calculated using the Atherosclerotic Cardiovascular Disease (ASCVD) scoring system. Dose-volume histograms were estimated for each cardiac chamber. A multivariate competing-risk regression analysis was conducted to assess each cardiac event's subhazard function (SHR).

RESULTS

The median follow-up was 27.5 months overall and 38.9 months for survivors. Among the 179 deaths, none was definitely related to cardiac conditions. Altogether, 32 cardiovascular events affected 27 patients (10.5%) after chemoradiotherapy. Ten were major cardiac adverse events, including heart failure (N = 6) and acute coronary syndrome (ACS, N = 4). Most cardiovascular events were related to well-known risk factors. However, the volume percentage of the left ventricle (LV) receiving 60 Gy (LV V60) > 0 was significantly associated with ACS (SHR = 9.49, 95% CI = 1.28-70.53, P = 0.028). In patients with high cardiovascular risk (ASCVD score > 7.5%), LV V60 > 0% remained a negative ACS prognostic factor (P = 0.003). Meanwhile, in patients with low cardiovascular risk, the LV radiation dose was not associated with ACS events (P = 0.242).

CONCLUSIONS

A high LV radiation dose could increase ACS events in patients with stage III NSCLC and high cardiovascular risk. Pre-treatment cardiac risk evaluation and individualized surveillance may help prevent cardiac events after chemoradiotherapy.

Treatment failure pattern of oropharyngeal cancer, especially for the aspect of retropharyngeal lymph node

e18565

Background: In radiotherapy for head and neck cancer, it is very important to define the appropriate treatment volumes that determine the treatment outcome and toxicity. We examined the feasibility of omitting elective retropharyngeal (RP) nodal irradiation in oropharyngeal cancer. Methods: We performed a retrospective review from 2009 to 2016; 197 patients with oropharyngeal squamous cell carcinomas were treated with definitive or postoperative radiation therapy at the Seoul National University Hospital or Seoul National University Bundang Hospital. Of these patients, 151 patients (76%) were treated ipsilateral RP nodal areas up to the upper edge of C1 vertebral body, while the other 46 patients (24%) were not. We reviewed patterns of failures, disease free survival, and patient-reported chronic xerostomia status in each patient group. Results: During follow-up period, 2 patient developed RP nodal recurrences (4-108 months, median =46 months). There was no significant between-group difference in disease free survival, with a rate of 80.7% in the high RP nodal-irradiation group and 87.2% in the RP nodal spared group (P=0.17). Patients in the high RP nodal-irradiation group had higher mean ipsilateral parotid gland dose (median 28.7±7.5 Gy vs. 21.3±7.6 Gy, P<0.001) and higher rates of chronic xerostomia (72.2% vs. 58.7%, P=0.030). Conclusions: Only 2 patients with omission of high RP node irradiation developed high RP node failure, and no significant difference in DFS was shown. Omission of high RP nodal irradiation resulted in reduced ipsilateral parotid gland dose, consequently with less chronic xerostomia.

Flexible film dosimeter for in vivo dosimetry

PURPOSE

The aims of this study were to develop a flexible film dosimeter applicable to the irregular surface of a patient for in vivo dosimetry and to evaluate the device's dosimetric characteristics.

METHODS

A flexible film dosimeter with active layers consisting of radiochromic-sensitive films and flexible silicone materials was constructed. The dose-response, sensitivity, scanning orientation dependence, energy dependence, and dose rate dependence of the flexible film dosimeter were tested. Irradiated dosimeters were scanned 24 h post-irradiation, and the region of interest was 5 mm × 5 mm. Biological stability tests ensured the safety of application of the flexible film dosimeter for patients. A preliminary clinical study with the flexible film dosimeter was implemented on four patients.

RESULTS

The red channel demonstrated the highest sensitivity among all channels, and the response sensitivity of the dosimeter decreased with the applied dose, which were the same as the characteristics of GAFCHROMIC EBT3 radiochromic films. The flexible film dosimeter showed no significant energy dependence for photon beams of 6 MV, 6 MV flattening filter-free (FFF), 10 MV, and 15 MV. The flexible film dosimeter showed no substantial dose rate dependence with 6 or 6 MV FFF. In terms of biological stability, the flexible film dosimeter demonstrated no cytotoxicity, no irritation, and no skin sensitization. In the preliminary clinical study, the dose differences between the measurements with the flexible film dosimeter and calculations with the treatment planning system ranged from -0.1% to 1.2% for all patients.

CONCLUSIONS

The dosimeter developed in this study is a flexible film capable of attachment to a curved skin surface. The biological test results indicate the stability of the flexible film dosimeter. The preliminary clinical study showed that the flexible film dosimeter can be successfully applied as an in vivo dosimeter.

Failure patterns of cervical lymph nodes in metastases of unknown origin according to target volume

Purpose

This study was aim to evaluate the patterns of failure according to radiotherapy (RT) target volume for cervical lymph nodes in metastases of unknown primary origin in head and neck region (HNMUO).

Materials and Methods

Sixty-two patients with HNMUO between 1998 and 2016 were retrospectively reviewed. We analyzed the clinical outcomes and primary site failure depending on the radiation target volume. The target volume was classified according to whether the potential head and neck mucosal sites were included and whether the neck node was treated involved side only or bilaterally.

Results

Potential mucosal site RT (mucosal RT) was done to 23 patients and 39 patients did not receive mucosal RT. Mucosal RT showed no significant effect on overall survival (OS) and locoregional recurrence (LRR). The location of primary site failure encountered during follow-up period was found to be unpredictable and 75% of patients with recurrence received successful salvage therapies. No significant differences in OS and LRR were found between patients treated to unilateral (n = 35) and bilateral neck irradiation (n = 21). Treatment of both necks resulted in significantly higher mucositis.

conclusions

We found no advantages in OS and LRR of patients with HNMUO when mucosal sites and bilateral neck node were included in the radiation target volume.

Risk stratification of symptomatic brain metastases by clinical and FDG PET parameters for selective use of prophylactic cranial irradiation in patients with extensive disease of small cell lung cancer

PURPOSE

To identify risk factors for developing symptomatic brain metastases and evaluate the impact of prophylactic cranial irradiation (PCI) on brain metastasis-free survival (BMFS) and overall survival (OS) in extensive disease small cell lung cancer (ED-SCLC).

MATERIALS AND METHODS

Among 190 patients diagnosed with ED-SCLC who underwent FDG PET/CT and brain Magnetic Resonance Imaging (MRI) prior to treatment, 53 (27.9%) received PCI while 137 (72.1%) did not. Prognostic index predicting a high risk of symptomatic brain metastases was calculated for the group without receiving PCI (observation group, n = 137) with Cox regression model.

RESULTS

Median follow-up time was 10.6 months. Multivariate Cox regression showed that the following three factors were associated with a high risk of symptomatic brain metastases: the presence of extrathoracic metastases (p = 0.004), hypermetabolism of bone marrow or spleen on FDG PET (p < 0.001), and high neutrophil-to-lymphocyte ratio (p = 0.018). PCI significantly improved BMFS in high-risk patients (1-year rate: 94.7% vs. 62.1%, p = 0.001), but not in low-risk patients (1-year rate: 100.0% vs. 87.7%, p = 0.943). However, PCI did not improve OS in patients at high risk for symptomatic brain metastases (1-year rate: 65.2% vs. 50.0%, p = 0.123).

CONCLUSION

Three prognostic factors (the presence of extrathoracic metastases, hypermetabolism of bone marrow or spleen on FDG PET, and high neutrophil-to-lymphocyte ratio) were associated with a high risk of symptomatic brain metastases in ED-SCLC. PCI was beneficial for patients at a high risk of symptomatic brain metastases in terms of BMFS, but not OS. Thus, selective use of PCI in ED-SCLC according to the risk stratification is recommended.

Contact lens-type ocular in vivo dosimeter for radiotherapy

PURPOSE

This study aimed to (a) develop a contact lens-type ocular in vivo dosimeter (CLOD) that can be worn directly on the eye and (b) assess its dosimetric characteristics and biological stability for radiation therapy.

METHODS

The molder of a soft contact lens was directly used to create the dosimeter, which included a radiation-sensitive component - an active layer similar to a radiochromic film - to measure the delivered dose. A flatbed scanner with a reflection mode was used to measure the change in optical density due to irradiation. The sensitivity, energy, dose rate, and angular dependence were tested, and the uncertainty in determining the dose was calculated using error propagation analysis. Sequential biological stability tests, specifically, cytotoxicity and ocular irritation tests, were conducted to ensure the safe application of the CLOD to patients.

RESULTS

The dosimeter demonstrated high sensitivity in the low dose region, and the sensitivity linearly decreased with the dose. The responses obtained for the 10 and 15 MV photon beams were 1.7% and 1.9% higher compared to the 6 MV photon beam. A strong dose rate dependence was not obtained for the CLOD. Angular dependence was observed from 90° to 180° with a difference in response from 1% to 2%. The total uncertainty in error propagation analysis decreased as a function of the dose in the red channel. For a dose range of 0 to 50 cGy, the total uncertainties for 5, 10, and 50 cGy were 14.2%, 8.9%, and 5%, respectively. Quantitative evaluation using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method presented no cytotoxicity. Further, no corneal opacity, iris reaction, or conjunctival inflammation was observed.

CONCLUSIONS

The CLOD is the first dosimeter that can be worn close to the eye. The results of cytotoxicity and irritation tests indicate that it is a stable medical device. The evaluation of dose characteristics in open field conditions shows that the CLOD can be applied to an in vivo dosimeter in radiotherapy.

Severe late dysphagia after multimodal treatment of stage III/IV laryngeal and hypopharyngeal cancer

Background

Long-term side effects after radiotherapy for organ preservation ‘could deteriorate’ the laryngeal function. This study intended to identify the incidence of severe late dysphagia following the multimodal treatment for stage III/IV laryngeal and hypopharyngeal cancer ‘to evaluate the function of larynx’.

Methods

The medical records of patients successfully treated for laryngeal and hypopharyngeal cancer with a multimodal approach, including radiotherapy, were retrospectively analyzed. ‘Functional larynx was defined as tolerable oral diet without severe late dysphagia or tracheostoma’.

Results

The study included 99 patients with a median follow-up period of 72 months. ‘Tracheostomy during the follow-up period was required in only one patient due to aspiration pneumonia, and dysphagia is the main determinant for functional larynx’. The probability of maintaining functional larynx was 63% for 10 years, when the treatment was started with radiotherapy or concurrent chemoradiotherapy. In upfront surgery (operation first and adjuvant radiotherapy/concurrent chemoradiotherapy) group, 37% of patients required total laryngectomy as primary treatment and 43% of patients could maintain laryngeal function for 10 years. And severe late dysphagia in the latter group developed mainly after laryngeal preservation surgery. The patients aged ≥65 years showed significantly higher incidence of dysphagia. Severe late dysphagia was very rare in laryngeal cancer successfully cured with radiotherapy/concurrent chemoradiotherapy (1/25, 4%); however, it gradually increased over time in hypopharyngeal cancer patients showing a statistically significant difference from laryngeal cancer patients (P = 0.040).

Conclusion

Severe late dysphagia occurred in 19.2% of patients treated for laryngeal and hypopharyngeal cancers, regardless of whether treatment started with radiotherapy/concurrent chemoradiotherapy or surgery.

Poor prognostic factors in human papillomavirus-positive head and neck cancer: who might not be candidates for de-escalation treatment?

BACKGROUND/AIMS

Since patients with human papillomavirus (HPV)-associated head and neck squamous cell carcinoma (HNSCC) have favorable outcomes after treatment, treatment de-escalation for these patients is being actively investigated. However, not all HPV-positive HNSCCs are curable, and some patients have a poor prognosis. The purpose of this study was to identify poor prognostic factors in patients with HPV-positive HNSCC.

METHODS

Patients who received a diagnosis of HNSCC and tested positive for HPV from 2000 to 2015 at a single hospital site (n = 152) were included in this retrospective analysis. HPV typing was conducted using the HPV DNA chip assay or liquid bead microarray system. Expression of p16 in the tumors was assessed by immunohistochemistry. To determine candidate factors associated with overall survival (OS), univariate and multivariable Cox regression analyses were performed.

RESULTS

A total of 152 patients with HPV-positive HNSCC were included in this study; 82.2% were male, 43.4% were current or former smokers, and 84.2% had oropharyngeal cancer. By univariate analysis, old age, performance status ≥ 1, non-oropharyngeal location, advanced T classification (T3-4), and HPV genotype 18 were significantly associated with poor OS. By multivariable analysis, performance status ≥ 1 and non-oropharyngeal location were independently associated with shorter OS (hazard ratio [HR], 4.36, p = 0.015; HR, 11.83, p = 0.002, respectively). Furthermore, HPV genotype 18 positivity was also an independent poor prognostic factor of OS (HR, 10.87, p < 0.001).

CONCLUSION

Non-oropharyngeal cancer, poor performance status, and HPV genotype 18 were independent poor prognostic factors in patients with HPV-positive HNSCC. Patients with these risk factors might not be candidates for de-escalation treatment.

Comparison of treatment plans between IMRT with MR-linac and VMAT for lung SABR

Background

The aim of this study was to compare the plan quality of magnetic-resonance image-based intensity modulated radiation therapy (MRI-based-IMRT) with the MRIdian Linac system to that of volumetric modulated arc therapy (VMAT) with the TrueBeam STx system for lung stereotactic ablative radiotherapy (SABR).

Methods

A total of 22 patients with tumors located in the lower lobe were retrospectively selected for the study. For each patient, both the MRI-based-IMRT and VMAT plans were generated using an identical CT image set and identical structures with the exception of the planning target volume (PTV). The PTVs of the MRI-based-IMRT were generated by adding an isotropic margin of 3 mm from the gross tumor volume, whereas those of VMAT were generated by adding an isotropic margin of 5 mm from the internal target volume. For both the MRI-based-IMRT and VMAT, the prescription doses to the PTVs were 60 Gy in four fractions.

Results

The average PTV volume of the MRI-based-IMRT was approximately 4-times smaller than that of VMAT (p <  0.001). The maximum dose to the bronchi for the MRI-based-IMRT was smaller than that for the VMAT (20.4 Gy versus 24.2 Gy, p <  0.001). In addition, V_40Gy of the rib for the MRI-based-IMRT was smaller than that for the VMAT (1.8 cm³ versus 7.7 cm³, p = 0.008). However, the maximum doses to the skin and spinal cord for the MRI-based-IMRT (33.0 Gy and 14.5 Gy, respectively) were larger than those for the VMAT (27.8 Gy and 11.0 Gy, respectively) showing p values of less than 0.02. For the ipsilateral lung, the mean dose, V_20Gy, V_10Gy, and V_5Gy for the MRI-based-IMRT were smaller than those for the VMAT (all with p <  0.05). For the contralateral lung, V_5Gy, V_10Gy, D_1500cc, and D_1000cc for the MRI-based-IMRT were larger than those for the VMAT (all with p <  0.05). The mean dose and V_50% of the whole body for the MRI-based-IMRT were smaller than those for the VMAT (0.9 Gy versus 1.2 Gy, and 78.7 cm³ versus 103.5 cm³, respectively, all at p <  0.001).

Conclusions

The MRI-based-IMRT using the MRIdian Linac system could reduce doses to bronchi, rib, ipsilateral lung, and whole body compared to VMAT for lung SABR when the tumor was located in the lower lobe.

Effect of changes in monitor unit rate and energy on dose rate of total marrow irradiation based on Linac volumetric arc therapy

Background

This study set out to evaluate the effect of dose rate on normal tissues (the lung, in particular) and the variation in the treatment efficiency as determined by the monitor unit (MU) and energy applied in Linac-based volumetric arc therapy (VMAT) total marrow irradiation (TMI).

Methods

Linac-based VMAT plans were generated for the TMI for six patients. The planning target volume (PTV) was divided into six sub-volumes, each of which had their own isocenter. To examine the effect of the dose rate and energy, a range of MU rates (40, 60, 80, 100, 300, and 600 MU/min) were selected for 6, 10, and 15 MV. All the plans were verified by portal dosimetry.

Results

The dosimetric parameters for the target and normal tissue were consistent in terms of the energy and MU rate. The beam-on time was changed from 59.6 to 6 min for 40 and 600 MU/min. When 40 MU/min was set for the lung, the dose rate delivered to the lung was less than 6 cGy/min (that is, 90%), while the beam-on time was approximately 10 min. The percentage volume of the lung receiving 20 cGy/min was 1.47, 3.94, and 6.22% at 6, 10, and 15 MV, respectively. However, for 600 MU/min, the total lung volume received over 6 cGy/min regardless of the energy, and over 20 cGy/min for 10 and 15 MV (i.e., 54.4% for 6 MV).

Conclusions

In TMI treatment, reducing the dose rate administered to the lung can decrease the incidence of pulmonary toxicity. To reduce the probability of normal tissue complications, the selection of the lowest MU rate is recommended for fields including the lung. To minimize the total treatment time, the maximum MU rate can be applied to other fields.

Electronic supplementary material

The online version of this article (10.1186/s13014-019-1296-y) contains supplementary material, which is available to authorized users.

A Phase II Study of Genexol-PM and Cisplatin as Induction Chemotherapy in Locally Advanced Head and Neck Squamous Cell Carcinoma

Lessons Learned.

Induction chemotherapy with Genexol‐PM and cisplatin demonstrated modest tumor response in locally advanced head and neck squamous cell carcinoma.

Considering favorable toxicity profiles and promising survival data, further studies on this regimen are warranted in patients with head and neck squamous cell carcinoma.

Background.

Genexol‐PM is a polymeric micellar formulation of paclitaxel without Cremophor EL. We investigated the efficacy and safety of Genexol‐PM plus cisplatin as induction chemotherapy (IC) in patients with locally advanced head and neck squamous cell carcinoma (LA‐HNSCC).

Methods.

Patients received Genexol‐PM (230 mg/m²) and cisplatin (60 mg/m²) every 3 weeks as IC. After three cycles of IC, definitive treatment of either concurrent chemoradiotherapy (CCRT) with weekly cisplatin (30 mg/m²) or surgery was performed. The primary endpoint was overall response rate (ORR) after IC.

Results.

Of 52 patients enrolled, 47 completed three cycles of IC, and the ORR was 55.8% (95% confidence interval, 42.3–69.3). Although there was one treatment‐related death, toxicity profiles to Genexol‐PM and cisplatin were generally favorable, and the most common grade 3 or 4 toxicities were neutropenia (15.4%), anorexia (7.7%), and general weakness (7.7%). Fifty‐one patients received definitive treatment (CCRT [n = 44] or radical surgery [n = 7]). The rate of complete response following CCRT was 81.8% (36/44). After a median follow‐up of 39 months, estimates of progression‐free survival (PFS) and overall survival (OS) at 3 years were 54.3% and 71.3%, respectively.

Conclusion.

IC with Genexol‐PM and cisplatin demonstrated modest tumor response with well‐tolerated toxicity profiles for patients with LA‐HNSCC.

Long-term oncological and functional outcomes of induction chemotherapy followed by (chemo)radiotherapy vs definitive chemoradiotherapy vs surgery-based therapy in locally advanced stage III/IV hypopharyngeal cancer: Multicenter review of 266 cases

OBJECTIVE

The aim of this study was to evaluate the treatment outcomes for stage III/IV locally advanced hypopharyngeal squamous cell carcinoma (SCC), comparing induction chemotherapy followed by (chemo)radiotherapy (ICT), definitive chemoradiotherapy (CRT) and surgery-based therapy (SRT).

SUBJECTS AND METHODS

Two hundred sixty-six patients with stage III/IV locally advanced hypopharyngeal squamous cell carcinoma (SCC) who underwent ICT (n = 74), CRT (n = 53) or SRT (n = 139) from 1997 through 2014 at the Seoul National University Hospital (n = 127) and the Hallym University Medical Center (n = 139) were enrolled in the study. All surgical procedures in the SRT group were performed by a single surgeon to eliminate surgeon bias.

RESULTS

The 5-year disease-free survival (DFS) and overall survival (OS) of all patients (n = 266) were 59.4% and 44%, respectively. The 5-year DFS rates after salvage treatment were 52.7% for ICT, 52.8% for CRT and 65.5% for SRT (p = 0.194). The OS rates were 44.6% for ICT, 39.6% for CRT and 45.3% for SRT group (p = 0.106). The salvage rates were 12.5% for ICT, 15.6% for CRT and 3.8% for SRT group. The final laryngeal preservation rate was significantly lower in the SRT group (44.6%) than in the ICT (71.6%) or CRT (71.7%) groups. All major postoperative complications were significantly higher in the salvage surgery group.

CONCLUSION

Treatment outcomes in the ICT and CRT groups were comparable to that of the SRT group for stage III/IV hypopharyngeal SCC. However, the relatively low chance of cure and high risk of complications should be taken into account when considering salvage surgery.