Radiation-induced second cancers: the impact of 3D-CRT and IMRT

[Does radiation therapy for prostate cancer increase the risk of second cancers?]

PURPOSE

The increased risk of second cancer after prostate radiotherapy is a debated clinical concern. The objective of the study was to assess the risk of occurrence of second cancers after prostate radiation therapy based on the analysis the literature, and to identify potential factors explaining the discrepancies in results between studies.

MATERIALS AND METHODS

A review of the literature was carried out, comparing the occurrence of second cancers in patients all presenting with prostate cancer, treated or not by radiation.

RESULTS

This review included 30 studies reporting the occurrence of second cancers in 2,112,000 patients treated or monitored for localized prostate cancer, including 1,111,000 by external radiation therapy and 103,000 by brachytherapy. Regarding external radiation therapy, the average follow-up was 7.3years. The majority of studies (80%) involving external radiation therapy, compared to no external radiation therapy, showed an increased risk of second cancers with a hazard ratio ranging from 1.13 to 4.9, depending on the duration of the follow-up. The median time to the occurrence of these second cancers after external radiotherapy ranged from 4 to 6years. An increased risk of second rectal and bladder cancer was observed in 52% and 85% of the studies, respectively. Considering a censoring period of more than 10 years after irradiation, 57% and 100% of the studies found an increased risk of rectal and bladder cancer, without any impact in overall survival. Studies of brachytherapy did not show an increased risk of second cancer. However, these comparative studies, most often old and retrospective, had many methodological biases.

CONCLUSION

Despite numerous methodological biases, prostate external radiation therapy appears associated with a moderate increase in the risk of second pelvic cancer, in particular bladder cancer, without impacting survival. Brachytherapy does not increase the risk of a second cancer.

Radiation Therapy Technology Advances and Mitigation of Subsequent Neoplasms in Childhood Cancer Survivors

PURPOSE

In this Pediatric Normal Tissue Effects in the Clinic (PENTEC) vision paper, challenges and opportunities in the assessment of subsequent neoplasms (SNs) from radiation therapy (RT) are presented and discussed in the context of technology advancement.

METHODS AND MATERIALS

The paper discusses the current knowledge of SN risks associated with historic, contemporary, and future RT technologies. Opportunities for research and SN mitigation strategies in pediatric patients with cancer are reviewed.

RESULTS

Present experience with radiation carcinogenesis is from populations exposed during widely different scenarios. Knowledge gaps exist within clinical cohorts and follow-up; dose-response and volume effects; dose-rate and fractionation effects; radiation quality and proton/particle therapy; age considerations; susceptibility of specific tissues; and risks related to genetic predisposition. The biological mechanisms associated with local and patient-level risks are largely unknown.

CONCLUSIONS

Future cancer care is expected to involve several available RT technologies, necessitating evidence and strategies to assess the performance of competing treatments. It is essential to maximize the utilization of existing follow-up while planning for prospective data collection, including standardized registration of individual treatment information with linkage across patient databases.

Modulated Arc Therapy for hippocampal-avoidance whole brain radiation therapy: planning comparison with intensity modulated Radiation Therapy

This study aimed to evaluate the modulated arc therapy (mARC) technique as a planning and treatment option for hippocampal sparing whole brain radiotherapy (HS-WBRT) following the Radiation Therapy Oncology Group (RTOG) 0933 dosimetric criteria. Computed tomography (CT) and magnetic resonance imaging (MRI) were selected retrospectively for 15 patients. Two types of plans were created for each patient, namely an intensity-modulated radiation therapy (IMRT) and a mARC plan. IMRT and mARC plans were compared in terms of plan quality indices, absorbed dose to organs at risk (OARs), number of monitor units (MUs), and treatment time. All plans in both techniques were considered clinically acceptable for treatment. However, IMRT plans presented a higher conformity (p = 0.01) as well as a higher homogeneity as compared to mARC plans, but this difference was not statistically significant (p > 0.05). In terms of the preservation of the hippocampus, it was observed that the IMRT plans achieved significantly lower doses for both 100% of its volume and for its maximum dose (p < 0.001). The evaluation of the remaining OARs showed that the IMRT technique resulted in lower doses, and significant differences were observed for the following organs: left cochlea (p < 0.001), left eye (p < 0.001), right eye (p = 0.03), both lenses of the eye (p < 0.001), and right optic nerve (p = 0.02). Despite these differences, the absolute differences in all dosimetric parameters were low enough to bear any clinical relevance. A drastic (close to 65%) and significant (p < 0.001) decrease was observed in the number of MUs for the mARC plans. This resulted in a substantial decrease in treatment time (60.45%, p < 0.001). It is concluded that the mARC technique is a feasible planning and treatment solution for HS-WBRT that meets the RTOG 0933 criteria. The main advantage of using mARC over IMRT for HS-WBRT is the considerable reduction in MUs and treatment time.

Interpretable deep learning insights: Unveiling the role of 1 Gy volume on lymphopenia after radiotherapy in breast cancer

BACKGROUND

Lymphopenia is known for its significance on poor survivals in breast cancer patients. Considering full dosimetric data, this study aimed to develop and validate predictive models for lymphopenia after radiotherapy (RT) in breast cancer.

MATERIAL AND METHODS

Patients with breast cancer treated with adjuvant RT were eligible in this multicenter study. The study endpoint was lympopenia, defined as the reduction in absolute lymphocytes and graded lymphopenia after RT. The dose-volume histogram (DVH) data of related critical structures and clinical factors were taken into account for the development of dense neural network (DNN) predictive models. The developed DNN models were validated using external patient cohorts.

RESULTS

A total of 918 consecutive patients with invasive breast cancer enrolled. The training, testing, and external validating datasets consisted of 589, 203, and 126 patients, respectively. Treatment volumes at nearly all dose levels of the DVH were significant predictors for lymphopenia following RT, including volumes at very low-dose 1 Gy (V1) of organs at risk (OARs) including lung, heart and body, especially ipsilateral-lung V1. A final DNN model, combining full DVH dosimetric parameters of OARs and three key clinical factors, achieved a predictive accuracy of 75 % or higher.

CONCLUSION

This study demonstrated and externally validated the significance of full dosimetric data, particularly the volume of low dose at as low as 1 Gy of critical structures on lymphopenia after radiation in patients with breast cancer. The significance of V1 deserves special attention, as modern VMAT RT technology often has a relatively high value of this parameter. Further study is warranted for RT plan optimization.

Hybrid Treatment Planning for Chest Wall Irradiation Utilizing Three-Dimensional Conformal Radiotherapy (3DCRT), Intensity-Modulated Radiation Therapy (IMRT), and Volumetric Modulated Arc Therapy (VMAT): A Systematic Review

Novel hybrid approaches for chest wall irradiation show promising outcomes regarding target coverage and sparing organs at risk (OARs). In this systematic review, we compared hybrid volumetric modulated arc therapy (H-VMAT) or hybrid intensity-modulated radiotherapy (H-IMRT) techniques with non-hybrid techniques, such as three-dimensional conformal radiation therapy (3DCRT), field-in-field (FIF), intensity-modulated arc therapy (IMRT), and volumetric modulated arc therapy (VMAT), for breast cancer patients with mastectomy. Our focus was the plan quality and dose distribution to the OARs. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, we performed a systematic review and quality appraisal of primary studies evaluating hybrid therapy to the chest wall and the OARs. An extensive online search of PubMed and Scopus databases was conducted using appropriate keywords. The dose to the OARs (lung, heart, and contralateral breast), planning target volume (PTV), homogeneity index (HI), and conformity index (CI) were extracted. The data were then tabulated and compared for the outcomes between modalities among the studies. Nine studies that met the search criteria were selected to evaluate the PTV coverage and dosimetric results of hybrid and non-hybrid techniques. In terms of 95% PTV coverage, among nine reviewed studies, the largest difference between the two techniques was between VMAT (47.6 Gy) and H-VMAT (48.4 Gy); for the conformity index, the largest difference was noted between 3DCRT (0.58) and H-VMAT (0.79). In both cases, differences were statistically significant (P < 0.005). Two studies showed dose homogeneity improvement within the treatment target in H-VMAT (0.15 and 0.07) compared with 3DCRT (0.41 and 0.12), with a P value of <0.001. Two studies did not report on the homogeneity index, and three others observed no statistical difference. Regarding OARs, in the comparison of H-VMAT and VMAT, the largest significant change was in the volume receiving 5 Gy (V5Gy) of the ipsilateral lung and the V10Gy of the contralateral lung. For the ipsilateral lung, V5Gy was 90.7% with VMAT versus 51.45% with H-VMAT. For the contralateral lung, V10Gy was 54.9% with VMAT versus 50.5% with H-VMAT. In six studies, the mean dose of the contralateral breast was lower in hybrid techniques than in single modalities: VMAT (4.2%, 6.0%, 1.9%, 7.1%, 4.57%) versus H-VMAT (1.4%, 3.4%, 1.8%, 3.5%, 2.34%) and IMRT (9.1%) versus H-IMRT (4.69%). Although most studies did not report on monitor units and treatment time, those that included them showed that hybrids had lower monitor units and shorter treatment times. Hybrid techniques in radiotherapy, such as combining two modalities, can indeed facilitate lower doses to OARs for patients with a high risk of toxicities. Prospective clinical studies are needed to determine the outcomes of breast cancer treated with hybrid techniques.

Radiation-Related Fractures after Radical Radiotherapy for Cervical and Endometrial Cancers: Are There Any Differences?

In this study, we reviewed CT/MRI scans and studied the rates of radiation-related fractures in subjects treated for cervical cancer (CC, 63 subjects) by radical radiotherapy (RT) and in subjects treated for endometrial cancer (EC, 64 subjects) by radical surgery and RT. The differences between bone density measured in L1 on pretreatment CT, age and body mass index (BMI) were evaluated. Despite significant differences in RT total dose, age, BMI, etc., between both groups, the rate of radiation-related fractures was similar: 28.6% of CC versus 26.6% of EC subjects. CC subjects with fractures were significantly older (62.4 ± 10.1 vs. 49.0 ± 12.4 years; p < 0.001), and their bone densities were significantly lower (106.3 ± 40.0 vs. 168.2 ± 49.5 HU; p < 0.001); no difference in BMI was found. EC subjects with fractures were without significant difference in age but had significantly lower bone densities (103.8 ± 29.0 vs. 133.8 ± 42.3 HU; p = 0.009) and BMIs (26.1 ± 4.9 vs. 31.8 ± 6.9 kg/m2; p = 0.003). Bone density strongly correlated with age (r = -0.755) only in CC subjects. Subjects with fractures from both groups had similarly low bone densities (106.3 ± 40.0 vs. 103.8 ± 29.0 HU; p = 0.829); however, no correlation between bone density and BMI was found. The rate of radiation-related fractures in both groups was clearly associated only with low pretreatment bone density, reflecting osteoporosis.

Stereotactic body radiotherapy with volumetric intensity-modulated arc therapy and flattening filter-free beams: dosimetric considerations

PURPOSE

The present study comparatively evaluates the impact of energy-matched flattening filter-free (FFF) photon beams with different energy levels on the physical-dosimetric quality of lung and liver stereotactic body radiotherapy (SBRT) treatment plans.

METHODS

For this purpose, 54 different lung and liver lesions from 44 patients who had already received SBRT combined with volumetric modulated arc therapy (VMAT) were included in this retrospective planning study. Planning computed tomography scans already available were used for the renewed planning with 6 MV, 6 MV-FFF, 10 MV, and 10 MV-FFF under constant planning objectives. The treatment delivery data, dosimetric distributions, and dose-volume histograms as well as parameters such as the conformity index and gradient indices were the basis for the evaluation and comparison of treatment plans.

RESULTS

A significant reduction of beam-on time (BOT) was achieved due to the high dose rates of FFF beams. In addition, we showed that for FFF beams compared to flattened beams of the same energy level, smaller planning target volumes (PTV) require fewer monitor units (MU) than larger PTVs. An equal to slightly superior target volume coverage and sparing of healthy tissue as well as organs at risk in both lung and liver lesions were found. Significant differences were seen mainly in the medium to lower dose range.

CONCLUSION

We found that FFF beams together with VMAT represent an excellent combination for SBRT of lung or liver lesions with shortest BOT for 10 MV-FFF but significant dose savings for 6 MV-FFF in lung lesions.

Deep-Learning for Rapid Estimation of the Out-of-Field Dose in External Beam Photon Radiation Therapy - A Proof of Concept

PURPOSE

The dose deposited outside of the treatment field during external photon beam radiation therapy treatment, also known as out-of-field dose, is the subject of extensive study as it may be associated with a higher risk of developing a second cancer and could have deleterious effects on the immune system that compromise the efficiency of combined radio-immunotherapy treatments. Out-of-field dose estimation tools developed today in research, including Monte Carlo simulations and analytical methods, are not suited to the requirements of clinical implementation because of their lack of versatility and their cumbersome application. We propose a proof of concept based on deep learning for out-of-field dose map estimation that addresses these limitations.

METHODS AND MATERIALS

For this purpose, a 3D U-Net, considering as inputs the in-field dose, as computed by the treatment planning system, and the patient's anatomy, was trained to predict out-of-field dose maps. The cohort used for learning and performance evaluation included 3151 pediatric patients from the FCCSS database, treated in 5 clinical centers, whose whole-body dose maps were previously estimated with an empirical analytical method. The test set, composed of 433 patients, was split into 5 subdata sets, each containing patients treated with devices unseen during the training phase. Root mean square deviation evaluated only on nonzero voxels located in the out-of-field areas was computed as performance metric.

RESULTS

Root mean square deviations of 0.28 and 0.41 cGy/Gy were obtained for the training and validation data sets, respectively. Values of 0.27, 0.26, 0.28, 0.30, and 0.45 cGy/Gy were achieved for the 6 MV linear accelerator, 16 MV linear accelerator, Alcyon cobalt irradiator, Mobiletron cobalt irradiator, and betatron device test sets, respectively.

CONCLUSIONS

This proof-of-concept approach using a convolutional neural network has demonstrated unprecedented generalizability for this task, although it remains limited, and brings us closer to an implementation compatible with clinical routine.

Second Malignancy Probabilities in Patients With Breast Cancer Treated With Conventional Versus Hypofractionated External Beam Radiation Therapy in the Adjuvant Setting

AIMS

For women with breast cancer, seminal studies have shown that adjuvant hypofractionated external beam radiation therapy (hEBRT) maintains similar outcomes and may reduce overall costs compared with conventionally fractionated external beam radiation therapy (cEBRT). However, it is unclear whether hEBRT may be associated with differential risk of development of radiation-induced second malignancies compared with cEBRT. Because the occurrence of second malignancies is small, large databases may improve our understanding of the relative risk of second malignancies between hEBRT and cEBRT.

MATERIALS AND METHODS

Using the National Cancer Database, we carried out a retrospective cohort analysis of women diagnosed with non-metastatic, stage 0-III breast cancer from 2004 to 2017. All patients had a lumpectomy or mastectomy and a follow-up time of at least 60 months after diagnosis. The probability of second malignancies in women receiving adjuvant cEBRT or hEBRT was compared using multivariable logistic regression adjusting for sociodemographic, geographical, clinical and treatment factors, allowing for relative (but not absolute) comparison of second malignancy risk. Temporal sensitivity analyses stratified by year of diagnosis and length of follow-up time were also conducted.

RESULTS

Of the 125 228 women in our study, 115 576 (92.3%) received cEBRT and 9652 (7.71%) received hEBRT. The median age of the cohort was 60 (interquartile range 51-68) years at diagnosis and the median follow-up time was 99.61 (interquartile range 77.5-128.49) months. Upon adjusting for sociodemographic and clinical factors, patients who received hEBRT had no difference in relative risk than patients who received cEBRT (odds ratio 0.937, 95% confidence interval 0.869-1.010, P = 0.091). In analyses stratified by year of diagnosis, and stratified by length of follow-up, there was no difference in second malignancy probability between patients who completed hEBRT and patients who completed cEBRT.

CONCLUSIONS

In this analysis of over 120 000 women with non-metastatic breast cancer, hEBRT was not associated with different odds of developing second malignancies compared with cEBRT. Our findings may inform patient counselling in the choice of radiation regimens for breast cancer and further support the safety of hypofractionated regimens for breast cancer.

Prognostic analysis of lung squamous cell carcinoma patients with second primary malignancies: a SEER database study

Background

As lung squamous cell carcinoma (LUSC) patients are at increased risk of developing a second primary cancer, this complicates the patient's condition and thus makes prognostic assessment more difficult, posing a significant prognostic challenge for clinicians. Our goal was to assess the prognosis of LUSC patients with a second primary tumor, and provide insights into appropriate therapy and monitoring strategies.

Methods

Data was obtained for LUSC patients from the Surveillance, Epidemiology, and End Results (SEER) database. The LUSC patients were divided into three groups (LS-SPM, OT-LUSC and LUSC-only). Univariate and stratified analyses were performed for the baseline and clinical characteristics of the participants. Multiple regression and Kaplan-Meier survival analyses were also performed, followed by a final life table analysis.

Results

In our sample of 101,626 patients, the HR for OS in the LS-SPM group was 0.40 in univariate analysis. Kaplan-Meier survival curves showed that LS-SPM patients had considerably longer lifespans compared to the other groups. The LS-SPM patients had median and mean survival times of 64 months and 89.11 months. Unadjusted and adjusted multiple regression analyses showed that LS-SPM patients had a superior survival compared to LUSC-only and OT-LUSC groups.

Conclusion

LS-SPM patients have a good prognosis with aggressive therapy and immune monitoring. The present study offers novel insights into the pathophysiological causes and treatments for LS-SPM.

Advances in radiation therapy for testicular seminoma

PURPOSE

Novel techniques and advances in radiation therapy (RT) have been explored to treat testicular seminoma, a highly radiosensitive and curable histology. We evaluated the historical and current indications for radiation therapy (RT) in testicular seminoma.

METHODS

A narrative literature review was performed. Studies of RT for testicular seminoma were included. Additionally, recent trials testing the use of combination or surgical therapies for clinical stage (CS) II were included. Search parameters included radiation therapy, testicular seminoma, surgery, and chemoradiation. Parameters and outcomes assessed were progression-free survival (PFS), overall survival (OS), acute toxicities, long-term sequelae, and rates of secondary malignancies.

RESULTS

Practice defining and changing studies in the use or omission of radiation therapy for testicular seminoma were identified along with resultant changes in National Comprehensive Cancer Network (NCCN) and European guidelines. Recent trials in combined chemoradiation and upfront surgical approaches to CS II disease were reviewed.

CONCLUSION

RT has historically been used as adjuvant treatment for CS I disease and is highly effective at treating CS II (A/B) testicular seminoma. The drive to maintain therapeutic efficacy and reduce acute and long-term side effects, namely secondary malignancies, is being tested using new radiation technologies, combined modality therapy in the form of chemoradiation and with upfront surgical approaches. Also, as guidelines now "strongly prefer" surveillance instead of adjuvant RT for CS I disease, the current CS II population comprises patients presenting with CS II disease ("de novo") and those who present with CSII after relapsing post orchiectomy for CS I ("relapsed"). Emerging evidence suggests that these two groups have different outcomes with respect to RT and chemoradiation. Consequently, future trials may need to sub-stratify according to these groups.

Quality assurance in a phase III, multicenter, randomized trial of POstmastectomy radioThErapy in Node posiTive breast cancer with or without Internal mAmmary nodaL irradiation (POTENTIAL): a planning benchmark case

PURPOSE

To report the planning benchmark case results of the POTENTIAL trial-a multicenter, randomized, phase 3 trial-to evaluate the value of internal mammary nodal (IMN) irradiation for patients with high-risk breast cancer.

METHODS

All participating institutions were provided the outlines of one benchmark case, and they generated radiation therapy plans per protocol. The plans were evaluated by a quality assurance team, after which the institutions resubmitted their revised plans. The information on beams arrangement, skin flash, inhomogeneity corrections, and protocol compliance was assessed in the first and final submission.

RESULTS

The plans from 26 institutions were analyzed. Some major deviations were found in the first submission. The protocol compliance rates of dose coverage for the planning target volume of chest wall, supraclavicular fossa plus axilla, and IMN region (PTVim) were all significantly improved in the final submission, which were 96.2% vs. 69.2%, 100% vs. 76.9%, and 88.4% vs. 53.8%, respectively. For OARs, the compliance rates of heart Dmean, left anterior descending coronary artery V40Gy, ipsilateral lung V5Gy, and stomach V5Gy were significantly improved. In the first and final submission, the mean values of PTVim V100% were 79.9% vs. 92.7%; the mean values of heart Dmean were 11.5 Gy vs. 9.7 Gy for hypofractionated radiation therapy and 11.5 Gy vs. 11.0 Gy for conventional fractionated radiation therapy, respectively.

CONCLUSION

The major deviations were corrected and protocol compliance was significantly improved after revision, which highlighted the importance of planning benchmark case to guarantee the planning quality for multicenter trials.

Animal Welfare in Radiation Research: The Importance of Animal Monitoring System

Long-term research into radiation exposure significantly expanded following World War II, driven by the increasing number of individuals falling ill after the detonation of two atomic bombs in Japan. Consequently, researchers intensified their efforts to investigate radiation's effects using animal models and to study disease models that emerged post-catastrophe. As a result, several parameters have been established as essential in these models, encompassing radiation doses, regimens involving single or multiple irradiations, the injection site for transplantation, and the quantity of cells to be injected. Nonetheless, researchers have observed numerous side effects in irradiated animals, prompting the development of scoring systems to monitor these animals' well-being. The aim of this review is to delve into the historical context of using animals in radiation research and explore the ethical considerations related to animal welfare, which has become an increasingly relevant topic in recent years. These concerns have prompted research groups to adopt measures aimed at reducing animal suffering. Consequently, for animal welfare, the implementation of a scoring system for clinical and behavioral monitoring is essential. This represents one of the primary challenges and hurdles in radiation studies. It is concluded that implementing standardized criteria across all institutions is aimed at ensuring result reproducibility and fostering collaboration within the scientific community.

The risk of second primary cancer after nasopharyngeal cancer: a systematic review

PURPOSE

Second primary cancers (SPCs) after nasopharyngeal cancer (NPC) are rare, but have an impact on the follow-up of this patient population. The aim of this study is to systematically review the literature to determine the prevalence and most typical sites of SPCs after NPC.

METHODS

We searched the databases of PubMed, Web of Science, and Scopus for articles on SPCs after NPC. The Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines were followed.

RESULTS

This review includes data on 89 168 patients with NPC from 21 articles. The mean occurrence for SPCs was 6.6% and varied from 4.9% in endemic areas to 8.7% in non-endemic areas. The most frequent locations of SPCs were oral cavity, pharynx, nose and paranasal sinuses, esophagus and lung.

CONCLUSION

There is an increased risk for a SPC after NPC management, especially in non-endemic areas. However, their mean rate is lower than after other head and neck carcinomas.

The Current Evidence of Intensity-Modulated Radiotherapy for Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis

Intensity-modulated radiotherapy (IMRT), an advanced RT technique, is a considerable treatment option for hepatocellular carcinoma (HCC). However, the distinguishing features of IMRT for HCC have not yet been clearly defined. A systematic review was performed according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The PubMed/MedLine, Embase, Cochrane Library, Web of Science, and KoreaMed were used to screen eligible studies focusing on treatment outcomes after IMRT for HCC until 18 April 2023. A total of 1755 HCC patients receiving IMRT among 29 studies from 2009 to 2023 were selected for the meta-analysis. The median proportion of Barcelona Clinic Liver Cancer stage C was 100% (range: 38-100%). Nineteen studies used combined treatment. Pooled rates of response and 1-year local control were 58% (95% confidence interval [CI], 50-65%) and 84% (95% CI, 70-94%), respectively. The median overall survival (OS) was 13 months (range: 5-45 months), and pooled 1- and 3-year OS rates were 59% (95% CI, 52-66%), and 23% (95% CI, 14-33%), respectively. Pooled rates of classic radiation-induced liver disease (RILD), nonclassic RILD, and hepatic toxicity ≥ grade 3 were 2%, 4%, and 4%, respectively. Although most patients had advanced-stage HCC and combined treatment was commonly used, IMRT for HCC showed similar survival to existing RT modalities and relatively low severe toxicity.

Dosimetric comparison of 3DCRT and IMRT in radical chemoradiotherapy of squamous cell carcinoma esophagus

BACKGROUND

Radical chemoradiation is the standard of treatment for locally advanced squamous cell carcinoma of esophagus and for patients with operable disease, but who are medically unfit or unwilling for surgery. As the esophagus is a central organ, the planning target volume (PTV) is central, lies close to the spinal cord and heart, and is surrounded by the lung, which is a radiosensitive organ. Irradiation of these critical structures is reduced by the use of three-dimensional conformal radiation therapy (3DCRT). Intensity-modulated radiation therapy (IMRT) has the potential to improve the uniformity of dose distribution to the tumor and reduce the dose received by surrounding normal tissues.

AIM AND OBJECTIVES

1. To compare the dose distribution, conformity, and homogeneity indices in radical radiotherapy of squamous cell carcinoma of esophagus using 3DCRT and IMRT techniques 2. To compare the doses received by critical structures such as heart, lung, spinal cord, and liver.

MATERIALS AND METHODS

All cases of squamous cell carcinoma esophagus treated with radical chemoradiation to a dose of 50 Gy in 25 fractions using 3DCRT technique from January 2018 to July 2019 were included. IMRT plans were generated for these cases.The parameters that represent dose distribution to the target volume and the dose received by the organs at risk were obtained from the dose-volume histogram. The difference in the mean values of the parameters between the two techniques was calculated. The statistical significance of the difference was determined using Student's t-test and Wilcoxon signed-rank test.

RESULTS

The volume of PTV receiving 105% and 107% of prescribed dose was significantly lower with IMRT (3.540% and 0.008%, respectively) compared to 3DCRT (7.654% and 0.623%). The homogeneity index was better with IMRT (0.088 vs. 0.107) than 3DCRT. Conformity index was found to be better with IMRT (1.149 vs. 1.573). Mean heart dose (18.216 vs. 24.591 Gy) and the volume of heart receiving 30 Gy were reduced with IMRT. The volume of lung receiving 20 Gy and the volume receiving 5 Gy were not significantly different between 3DCRT and IMRT. Maximum dose to spinal cord was similar with 3DCRT and IMRT.

CONCLUSIONS

IMRT avoids areas of excessive irradiation within the PTV. IMRT improves dose conformity to the target volume and homogeneity of dose distribution within the PTV. The cardiac dose is significantly reduced with IMRT. The mean lung dose remains similar to 3DCRT. There is no significant increase in the volume of lung receiving low-dose radiation with IMRT.

Dosimetric Comparison of Unmatched Flattening Filter-free and Flattened Beams in Volumetric Arc Therapy Plans for Head-and-neck Cancer

Introduction

Conventionally, the fattened beam is being used in radiotherapy for routine clinical cases even after introduction of intensity-modulated radiotherapy with incorporation of multi-leaf collimator system. With the removal of the flattening filter (FF) from the beam's path average energy of the photon gets reduced resulting in reduced scatter, reduction in treatment time, and reduced neutron contamination for high-energy beam and ultimately resulting in treatment plan quality deviations. This study aims to investigate the usefulness of the FF-free (FFF) beam for routine head-and-neck cancer (HNC) cases treated with volumetric arc therapy (VMAT) and dosimetrically compares the result with the FF beam.

Materials and Methods

In this study, 20 patients treated on HalcyonTM (unmatched 6 megavoltage [6MV] FFF beam) medical linear accelerator with VMAT of different HNC selected and for comparison with 6MV FF beam, 20 equivalent treatment plans are created for TruebeamTM configuration and the plans have been evaluated for target coverage, doses to the organ at risk (OAR), and other dose quality indices.

Results

Comparable target coverage, doses to OARs except for rest right parotid (P = 0.02) between 6MV FFF beam and 6MV FF beam is observed. Insignificant differences in conformity index, homogeneity index, and gradient index have been observed. Higher monitor unit (MU) (P ≤ 0.001) and lesser beam on time (BOT) (P = 0.003) have been observed in 6MV FFF.

Conclusion

6MV FFF beam provides comparable target coverage and improved dose-sparing effect to most of the OARs. 6MV FFF beam has lesser BOT, but on the other hand number of MUs is higher as compared to 6MV-FF plans.

High dose (54 Gy) pre-operative helical tomotherapy for retroperitoneal liposarcoma: Results of a phase II multicenter study

PURPOSE

To evaluate efficacy and feasibility of high-dose intensity-modulated radiotherapy (RT) with pre-operative helical tomotherapy, delivering 54 Gy/30 fractions in patients with retroperitoneal liposarcomas (RPLS).

MATERIALS AND METHODS

Patients with operable, biopsy-proven, RPLS were included in this phase II multicenter study (ClinicalTrials.gov: NCT01841047). The primary objectives were to analyze loco-regional relapse free survival (LRFS), overall survival (OS) and toxicities, graded according to CTCAE V3.0.

RESULTS

From April 2009 to September 2013, 48 patients were included. Histological types were: 20 well differentiated and 28 dedifferentiated liposarcomas. Median clinical target volume (CTV) was 2570 cc (range, 230-8734 cc). The radio-surgical schedule was completed as planned in all patients apart from one. A monobloc wide excision was achieved for all patients. Surgical margins were R0 (16; 34%), R1 (28; 60%), R2 (2; 4%) or missing (1, 2%).With a median follow-up of 5.5 years, 3-year LRFS rate was 74.2% (95%CI: [59.1%; 84.5%]). At 5 years, cumulative incidence of loco-regional relapse for well differentiated and dedifferentiated RPLS was 10% and 18%, respectively. The 5-year OS was 73.9% [95%CI: 58.7-84.3%]. During RT, the most common grade 3-4 adverse events were hematological (N = 20; 41.6%). After surgery and during follow-up, 17 patients (35.4%) presented a grade 3-4 toxicity. Two patients (4.1%) died due to a duodenal toxicity. Nine second cancers were observed.

CONCLUSION

From this phase II trial of preoperative RT in RPLS patients, the dose level proposed cannot be considered safe, leading to non-negligible toxicity and second cancers rates. Our results, combined with STRASS-1 study, suggest that the ideal indication of RT for patients with RPLS still remains to be determined.

Cancer Control, Toxicity, and Secondary Malignancy Risks of Proton Radiation Therapy for Stage I-IIB Testicular Seminoma

Purpose

This study's objective was to report cancer control and toxicity outcomes after proton radiation therapy (RT) in testicular seminoma and to compare secondary malignancy (SMN) risks with photon-based treatment alternatives.

Methods and Materials

Consecutive patients with stage I-IIB testicular seminoma treated with proton RT at a single institution were retrospectively analyzed. Kaplan-Meier estimates for disease-free and overall survival were computed. Toxicities were scored using Common Terminology Criteria for Adverse Events version 5.0. Photon comparison plans, including 3-dimensional conformal RT (3D-CRT) and intensity modulated RT (IMRT)/volumetric arc therapy (VMAT), were created for each patient. Dosimetric parameters and SMN risk predictions for different in-field organs-at-risk were compared between the techniques. Excess absolute SMN risks were estimated with organ equivalent dose modeling.

Results

Twenty-four patients were included (median age, 38.5 years). The majority of patients had stage II disease (IIA, 12 [50.0%]; IIB, 11 [45.8%]; IA, 1 [4.2%]). Seven (29.2%) and 17 (70.8%) patients had de novo and recurrent disease, respectively (de novo/recurrent: IA, 1/0; IIA, 4/8; IIB, 2/9). Most acute toxicities were mild (grade 1 [G1], 79.2%; G2, 12.5%) with G1 nausea being most common (70.8%). No serious events (G3-5) occurred. With a median follow-up time of 3 years (interquartile range, 2.1-3.6 years), 3-year disease-free and overall survival rates were 90.9% (95% confidence interval, 68.1%-97.6%) and 100% (95% confidence interval, 100%-100%), respectively. There were no documented late toxicities in the follow-up period, including worsening serial creatinine levels suggestive of early nephrotoxicity. Proton RT had significant reductions in mean organ-at-risk doses to the kidneys, stomach, colon, liver, bladder, and body compared with both 3D-CRT and IMRT/VMAT. Proton RT had significantly lower SMN risk predictions compared with 3D-CRT and IMRT/VMAT.

Conclusions

Cancer control and toxicity outcomes using proton RT in stage I-IIB testicular seminoma are consistent with existing photon-based RT literature. However, proton RT may be associated with significantly lower SMN risks.

Exploring the Aggressiveness of Sarcomatoid Carcinoma of the Oral Cavity - an Institutional Experience

Background: Sarcomatoid variant of squamous cell carcinoma in the oral cavity is a rare biphasic variant of squamous cell carcinoma. This aggressive variant of squamous cell carcinoma is characterized by invasive growth with marked local recurrence and distant metastasis resulting in poor prognosis. Sarcomatoid carcinoma can occur over a wide age range, incidence increases with older age and is a male-predominant disease. Methods: 23 patients with histologically proven Sarcomatoid SCC or with a sarcomatoid component (Group A) were compared with 23 randomly chosen patients with clinical stage IV (Group B) disease at the time of diagnosis, within the same time period and comparison was made between disease free survival and overall survival. Results: In group A, the mean DFS was found to be 12.4 months raging from 1 month to 36 months. 6 patients were therafter lost to follow follow up, in 11 patients the mean overall survival was found to be 8.72 months (ranging from 2 to 18 months) whereas 6 patients are alive till date. In group B, the mean DFS was found to be 19.56 months ranging from 6 months to 33 months. 4 patients succumbed to the disease with a mean overall survival of 24.25 years (ranging from 18 to 33 months), 4 patients were lost to follow up and the rest are alive till date. Conclusion: Sarcomatoid carcinoma of the oral cavity is an extremely rare but aggressive variant of conventional squamous cell carcinoma. We have to systematically understand their clinical, morphological and immunohistochemical features which is critical for their accurate diagnosis which aids in correct patient management. After radical surgery and adjuvant radiation therapy, strict follow up for development of recurrence and distant metastasis should be done.

Risk evaluation of secondary malignancies after radiotherapy of breast cancer in light of the continuous development of planning techniques

Secondary cancer risk is a significant concern for women treated with breast radiation therapy due to improved long-term survival rates. We evaluated the potential of new advanced automated planning algorithms together with hybrid techniques to minimize the excess absolute risk (EAR) for secondary cancer in various organs after radiation treatment for early staged breast cancer. Using CT data set of 25 patients, we generated 4 different radiation treatment plans of different complexity, including 3-dimensional conformal radiotherapy (3D-CRT), field-in-field (FinF), hybrid-IMRT (HMRT) and automated hybrid-VMAT (HVMAT) techniques. The organ-equivalent dose (OED) was calculated from differential dose-volume histograms on the basis of the "linear-exponential," "plateau," and "full mechanistic" dose-response models and was used to evaluate the EAR for secondary cancer in the contralateral breast (CB), contralateral lung (CL), and ipsilateral lung (IL). Statistical comparisons of data were performed by a Kruskal-Wallis analysis of variance. The planning objectives were fulfilled with all the planning techniques for both target coverage and organs-at-risk sparing. The differences in EAR for CB, CL and IL secondary tumor induction were not significant among the 4 techniques. For the CB and CL, the mean absolute difference did not reach 1 case of 10000 patient-years. For the IL, the mean absolute difference was up to 5 cases of 10,000 patient-years. In conclusion, the automated HVMAT technique allows an EAR reduction at the level of well-consolidated tangential 3D-CRT or FinF techniques, keeping all the HVMAT dosimetric improvements unchanged. On the basis of this analysis, the adoption of the HVMAT technique poses no increase in EAR and could be considered safe also for younger patients.

TP53 and the Ultimate Biological Optimization Steps of Curative Radiation Oncology

The new biological interaction cross-section-based repairable-homologically repairable (RHR) damage formulation for radiation-induced cellular inactivation, repair, misrepair, and apoptosis was applied to optimize radiation therapy. This new formulation implies renewed thinking about biologically optimized radiation therapy, suggesting that most TP53 intact normal tissues are low-dose hypersensitive (LDHS) and low-dose apoptotic (LDA). This generates a fractionation window in LDHS normal tissues, indicating that the maximum dose to organs at risk should be ≤2.3 Gy/Fr, preferably of low LET. This calls for biologically optimized treatments using a few high tumor dose-intensity-modulated light ion beams, thereby avoiding secondary cancer risks and generating a real tumor cure without a caspase-3-induced accelerated tumor cell repopulation. Light ions with the lowest possible LET in normal tissues and high LET only in the tumor imply the use of the lightest ions, from lithium to boron. The high microscopic heterogeneity in the tumor will cause local microscopic cold spots; thus, in the last week of curative ion therapy, when there are few remaining viable tumor clonogens randomly spread in the target volume, the patient should preferably receive the last 10 GyE via low LET, ensuring perfect tumor coverage, a high cure probability, and a reduced risk for adverse normal tissue reactions. Interestingly, such an approach would also ensure a steeper rise in tumor cure probability and a higher complication-free cure, as the few remaining clonogens are often fairly well oxygenated, eliminating a shallower tumor response due to inherent ion beam heterogeneity. With the improved fractionation proposal, these approaches may improve the complication-free cure probability by about 10-25% or even more.

Application of tangent-arc technology for deep inspiration breath-hold radiotherapy in left-sided breast cancer

Objective

To explore the advantages of dosimetry and the treatment efficiency of tangent-arc technology in deep inspiration breath-hold radiotherapy for breast cancer.

Methods

Forty patients with left-sided breast cancer who were treated in our hospital from May 2020 to June 2021 were randomly selected and divided into two groups. The first group's plan was a continuous semi-arc that started at 145° ( ± 5°) and stopped at 325° ( ± 5°). The other group's plan, defined as the tangent-arc plan, had two arcs: the first arc started at 145° ( ± 5°) and stopped at 85° ( ± 5°), and the second arc started at 25° ( ± 5°) and stopped at 325° ( ± 5°). We compared the target dose, dose in organs at risk (OARs), and treatment time between the two groups.

Results

The target dose was similar between the continuous semiarc and tangent-arc groups. The V5 of the right lung was significantly different between the two groups (Dif 5.52, 95% confidence interval 1.92-9.13, t=3.10, P=0.004), with the patients in the continuous semi-arc and tangent-arc groups having lung V5 values of (9.16 ± 1.62)%, and (3.64 ± 0.73)%, respectively. The maximum dose to the spinal cord was (1835.88 ± 222.17) cGy in the continuous semi-arc group and (599.42 ± 153.91) cGy in the tangent-arc group, yielding a significant difference between the two groups (Dif 1236.46, 95% confidence interval 689.32-1783.6, t=4.57, P<0.001). The treatment times was (311.70 ± 60.45) s for patients in the continuous semi-arc group and (254.66 ± 40.73) s for patients in the tangent-arc group, and there was a significant difference in the mean number of treatment times between the two groups (Dif 57.04, 95% confidence interval 24.05-90.03, t=3.5, P=0.001).

Conclusion

Both the continuous semi-arc and tangent-arc plans met the clinical prescription dose requirements. The OARs received less radiation with the tangent-arc plan than the continuous semi-arc plan, especially for the lung (measured as V5) and the spinal cord (measured as the maximum dose). Tangent-arc plan took significantly less time than the continuous semi-arc, which can greatly improve treatment efficiency. Therefore, tangent-arc plans are superior continuous semi-arc plans for all cases.

Comparing Risk for Second Primary Cancers After Intensity-Modulated vs 3-Dimensional Conformal Radiation Therapy for Prostate Cancer, 2002-2015

Importance

Compared with 3-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT) can spare nearby tissue but may result in increased scatter radiation to distant normal tissue, including red bone marrow. It is unclear whether second primary cancer risk varies by radiotherapy type.

Objective

To evaluate whether radiotherapy type (IMRT vs 3DCRT) is associated with second primary cancer risk among older men treated for prostate cancer.

Design, Setting, and Participants

In this retrospective cohort study of a linked database of Medicare claims and Surveillance, Epidemiology, and End Results (SEER) Program population-based cancer registries (2002-2015), male patients aged 66 to 84 diagnosed with a first primary nonmetastatic prostate cancer from 2002 to 2013, as reported to SEER, and who received radiotherapy (IMRT and/or 3DCRT without proton therapy) within the first year following prostate cancer were identified. The data were analyzed from January 2022 through June 2022.

Exposure

Receipt of IMRT and 3DCRT, based on Medicare claims.

Main Outcomes and Measures

The association between radiotherapy type and development of a subsequent hematologic cancer at least 2 years after prostate cancer diagnosis or a subsequent solid cancer at least 5 years after prostate cancer diagnosis. Hazard ratios (HRs) and 95% CIs were estimated using multivariable Cox proportional regression.

Results

The study included 65 235 2-year first primary prostate cancer survivors (median [range] age, 72 [66-82] years; 82.2% White patients) and 45 811 5-year survivors with similar demographic characteristics (median [range] age, 72 [66-79] years; 82.4% White patients). Among 2-year prostate cancer survivors (median [range] follow-up, 4.6 [0.003-12.0] years), 1107 second hematologic cancers were diagnosed (IMRT, 603; 3DCRT, 504). Radiotherapy type was not associated with second hematologic cancers overall or any specific types evaluated. Among 5-year survivors (median [range] follow-up, 3.1 [0.003-9.0] years), 2688 men were diagnosed with a second primary solid cancer (IMRT, 1306; 3DCRT, 1382). The overall HR for IMRT vs 3DCRT was 0.91 (95% CI, 0.83-0.99). This inverse association was restricted to the earlier calendar year period of prostate cancer diagnosis (HR2002-2005 = 0.85; 95% CI, 0.76-0.94; HR2006-2010 = 1.14; 95% CI, 0.96-1.36), with a similar pattern observed for colon cancer (HR2002-2005 = 0.66; 95% CI, 0.46-0.94; HR2006-2010 = 1.06; 95% CI, 0.59-1.88).

Conclusions and Relevance

The results of this large, population-based cohort study suggest that IMRT for prostate cancer is not associated with an increased risk of second primary cancers, either solid or hematologic, and any inverse associations may be associated with calendar year of treatment.

Ferrocene-Based Drugs, Delivery Nanomaterials and Fenton Mechanism: State of the Art, Recent Developments and Prospects

Ferrocene has been the most used organometallic moiety introduced in organic and bioinorganic drugs to cure cancers and various other diseases. Following several pioneering studies, two real breakthroughs occurred in 1996 and 1997. In 1996, Jaouen et al. reported ferrocifens, ferrocene analogs of tamoxifen, the chemotherapeutic for hormone-dependent breast cancer. Several ferrocifens are now in preclinical evaluation. Independently, in 1997, ferroquine, an analog of the antimalarial drug chloroquine upon the introduction of a ferrocenyl substituent in the carbon chain, was reported by the Biot-Brocard group and found to be active against both chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum. Ferroquine, in combination with artefenomel, completed phase IIb clinical evaluation in 2019. More than 1000 studies have been published on ferrocenyl-containing pharmacophores against infectious diseases, including parasitic, bacterial, fungal, and viral infections, but the relationship between structure and biological activity has been scarcely demonstrated, unlike for ferrocifens and ferroquines. In a majority of ferrocene-containing drugs, however, the production of reactive oxygen species (ROS), in particular the OH. radical, produced by Fenton catalysis, plays a key role and is scrutinized in this mini-review, together with the supramolecular approach utilizing drug delivery nanosystems, such as micelles, metal-organic frameworks (MOFs), polymers, and dendrimers.

Dosimetric Comparision of Coplanar versus Noncoplanar Volumetric Modulated Arc Therapy for Treatment of Bilateral Breast Cancers

Introduction

The purpose of this study was to compare the dosimetric parameters of volumetric modulated arc therapy (VMAT) treatment plans using coplanar and noncoplanar beams in patients with bilateral breast cancer/s (BBCs) in terms of organ at risk sparing and target volume coverage. The hypothesis was to test whether VMAT with noncoplanar beams can result in lesser dose delivery to critical organs such as heart and lung, which will result in lesser overall toxicity.

Materials and Methods

Data of nine BBC cases treated at our hospital were retrieved. Computed tomography simulation data of these cases was used to generate noncoplanar VMAT plans and the parameters were compared with standard VMAT coplanar plans. Contouring was done using radiation therapy oncology group guidelines. Forty-five Gray in 25 fractions was planned followed by 10 Gy in five fractions boost in breast conservation cases.

Results

No significant difference in planning target volume (PTV) coverage was found for the right breast/chestwall (P = 0.940), left breast/chestwall (P = 0.872), and in the total PTV (P = 0.929). Noncoplanar beams resulted in better cardiac sparing in terms of Dmean heart. The difference in mean dose was >1 Gy (8.80 ± 0.28 - 7.28 ± 0.33, P < 0.001). The Dmean, V20 and V30 values for total lung slightly favor noncoplanar beams, although there was no statistically significant difference. The average monitor units (MUs) were similar for coplanar plans (1515 MU) and noncoplanar plans (1455 MU), but the overall treatment time was higher in noncoplanar plans due to more complex setup and beam arrangement. For noncoplanar VMAT plans, the mean conformity index was slightly better although the homogeneity indices were similar.

Conclusion

VMAT plans with noncoplanar beam arrangements had significant dosimetric advantages in terms of sparing of critical organs, that is Dmean of heart doses with almost equivalent lung doses and equally good target coverage. Larger studies with clinical implications need to be considered to validate this data.

A dosimetric comparison of intensity-modulated radiotherapy versus rapid arc in gynecological malignancies: Dose beyond planning target volume, precisely 5Gy volume

Introduction

Aim of radiotherapy is precise dose delivery with objective of achieving maximum local control and minimal toxicity by decreasing dose to organ at risk (OAR).This aim can be achieved by technologies like intensity-modulated radiotherapy (IMRT) and volumetric arc therapy. However, later offers comparable or even better plan quality with shorter treatment time. It is important to note that low dose regions are also a concern due long-term risk of developing a second cancer after radiotherapy. The objective of our study is to do dosimetric comparison of IMRT vs. Rapid arc (RA) plan in gynecology cancer and specifically to assess dose beyond planning target volume (PTV), precisely 5 Gy volume.

Methods

Each 20 eligible patients underwent radiotherapy planning on eclipse by both IMRT and RA plans as per institution protocols. Comparative dosimetric analysis of both plans was done by paired sample t-test. PTV metrics compared were D95%, homogenecity index (HI), and conformity index (CI). OAR dose compared were bowel V40 Gy <30%, Rectum V30 Gy <60%, Bladder V45 Gy <35%, and bilateral femur head and neck V30 Gy < 50%. Futhermore, calculated monitor units (MUs) were also compared. Finally, volume of normal tissue beyond the PTV, specifically 5 Gy volume, was compared between plans.

Results

Dosimetric plan comparison showed statistically significant difference in RA and IMRT plans with improved PTV coverage and better OAR tolerance with RA plan. In addition, MU used were significantly less in RA plan, coupled with reduced V5 Gy volume.

Conclusion

In sum, RA plans are dosimetrically significantly better compared to IMRT plans in gynecological malignancies in terms of PTV coverage and OAR sparing. Importantly, not only less MU used but also significantly less normal tissue V5 Gy volume is less in RA compared to IMRT plans.

Dosimetry study of Auto-VMAT planning and Manual-VMAT planning based on Pinnacle3 9.10 in radiotherapy for cervical cancer

The purpose of this study was to compare the dose distribution characteristics of automatic volume-modulated arc therapy (Auto-VMAT) planning and manual volume-modulated arc therapy (Manual-VMAT) planning of Philips Pinnacle3 9.10 planning system, to provide a basis for optimal radiation therapy planning for cervical cancer. Ten patients with cervical cancer in our hospital from September to December 2018 were selected, and 2 treatment plans, Auto-VMAT plan and Manual-VMAT plan, were designed using Pinnacle3 9.10 planning system, respectively, to evaluate the maximum dose Dmax, mean dose Dmean, homogeneity index of the target area according to the dose volume histogram, the conformability index, plan optimization time, monitor units (MUs), organ at risk and other indicators. The results were that the Auto-VMAT plan was superior to the Manual-VMAT plan for target area Dmean, conformability index, and homogeneity index, with statistically significant differences (P < .05) and no significant difference in maximum dose Dmax (P > .05); rectal V40, V50, and Dmean in the Auto-VMAT plan, bladder V40, V50, and Dmean, small bowel V30, V40, V50 and Dmean, and right and left femoral V50 and Dmean were all lower than the Manual-VMAT plan, and the difference was statistically significant (P < .05); the mean optimization time for the Auto-VMAT and Manual-VMAT plans was 47 minutes and 35 minutes, respectively, an increase of 34%. The average number of MUs was 519 MUs and 374 MUs, respectively, an increase of 28%. This study concluded that the Pinnacle3 9.10-based Auto-VMAT plan was clinically feasible and significantly superior to the Manual-VMAT plan in terms of improved target area uniformity and conformability and reduced organ endangerment dose while reducing the impact of human factors on the quality of plan design.

Clinicopathologic characteristics of second primary squamous cell carcinoma in patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy

To compare the clinicopathologic characteristics of second primary squamous cell carcinoma (SPSCC) in patients with nasopharyngeal carcinoma (NPC) after intensity-modulated radiotherapy (IMRT) with that after radiotherapy (RT). From 49,021 patients with NPC who treated by definitive RT, we were able to identify 15 male patients with SPSCC after IMRT, and 23 male patients with SPSCC after RT. We examined the difference between groups. In IMRT group, 50.33% developed SPSCC within 3 years, whereas 56.52% developed SPSCC after more than 10 years in RT group. Receiving IMRT was related positively to an increased risk of SPSCC (HR = 4.25; P < 0.001). There was no significant correlation between receiving IMRT and the survival of SPSCC (P = 0.051). Receiving IMRT was related positively to an increased risk of SPSCC, and the latency was much shorter. A follow-up protocol, especially in the first three years, should be designed for NPC patients with IMRT.

Analytical models for external photon beam radiotherapy out-of-field dose calculation: a scoping review

A growing body of scientific evidence indicates that exposure to low dose ionizing radiation (< 2 Gy) is associated with a higher risk of developing radio-induced cancer. Additionally, it has been shown to have significant impacts on both innate and adaptive immune responses. As a result, the evaluation of the low doses inevitably delivered outside the treatment fields (out-of-field dose) in photon radiotherapy is a topic that is regaining interest at a pivotal moment in radiotherapy. In this work, we proposed a scoping review in order to identify evidence of strengths and limitations of available analytical models for out-of-field dose calculation in external photon beam radiotherapy for the purpose of implementation in clinical routine. Papers published between 1988 and 2022 proposing a novel analytical model that estimated at least one component of the out-of-field dose for photon external radiotherapy were included. Models focusing on electrons, protons and Monte-Carlo methods were excluded. The methodological quality and potential limitations of each model were analyzed to assess their generalizability. Twenty-one published papers were selected for analysis, of which 14 proposed multi-compartment models, demonstrating that research efforts are directed towards an increasingly detailed description of the underlying physical phenomena. Our synthesis revealed great inhomogeneities in practices, in particular in the acquisition of experimental data and the standardization of measurements, in the choice of metrics used for the evaluation of model performance and even in the definition of regions considered out-of-the-field, which makes quantitative comparisons impossible. We therefore propose to clarify some key concepts. The analytical methods do not seem to be easily suitable for massive use in clinical routine, due to the inevitable cumbersome nature of their implementation. Currently, there is no consensus on a mathematical formalism that comprehensively describes the out-of-field dose in external photon radiotherapy, partly due to the complex interactions between a large number of influencing factors. Out-of-field dose calculation models based on neural networks could be promising tools to overcome these limitations and thus favor a transfer to the clinic, but the lack of sufficiently large and heterogeneous data sets is the main obstacle.

Advancing Precision in Post-mastectomy Chest Wall Radiotherapy: A Comparative Dosimetric Analysis of Volumetric-Modulated Arc Therapy (VMAT) and Intensity-Modulated Radiotherapy (IMRT) Based on Institutional Experience

BACKGROUND

Post-mastectomy radiation therapy (PMRT) is an important component in the management of breast cancer patients who have undergone mastectomy. Intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) are two popular methods of delivering PMRT. With IMRT, high radiation doses are directed at the tumor, while exposure to healthy tissue is kept to a minimum. VMAT, on the other hand, is a more advanced version of IMRT that allows for faster radiation dose delivery while maintaining precision. The complexity of the VMAT treatment planning and delivery process, on the other hand, may increase the risk of technical errors, which can reduce treatment effectiveness.  Studies have compared VMAT and IMRT in PMRT for breast cancer patients, but most have found no significant differences in treatment outcomes between the two methods. Individual patient factors such as treatment goals, available resources, and other characteristics may influence the choice between the two techniques.

PURPOSE

 This prospective observational study aimed to compare the dosimetry of two cutting-edge modern radiotherapy techniques for post-mastectomy breast cancer patients receiving hypofractionated doses.

METHODS

 For 58 patients with breast cancer, 116 plans for radiotherapy treatment were generated by both VMAT and IMRT. To maintain the uniformity of contouring, every CT image was contoured by the same physician, and Radiotherapy Oncology Group (RTOG) contouring guidelines were strictly followed during contouring.

RESULTS

Both techniques had comparable target volume coverage, but VMAT produced a significantly better conformity index than IMRT for both the left (0.71 vs. 0.65) and right (0.72 vs. 0.66) breasts (p-value < 0.05). VMAT plans had significantly higher low-dose spillage to the ipsilateral lung (V5Gy and V10Gy) but significantly lower high-dose spillage (V20Gy, V30Gy, and V40Gy) than IMRT plans (p-value < 0.05). Dmax and Dmean for the ipsilateral lung were comparable for both techniques. When compared to alternative treatment approaches, IMRT treatment plans were found to be more effective in minimizing radiation exposure to the heart for all patients with right-sided breast cancer, resulting in considerably lower levels of Dmean, V5Gy, V10Gy, V20Gy, and V35Gy. Plans for VMAT treatment were found to be significantly superior to left-side chest wall radiotherapy in terms of lower exposure to the heart for higher doses. IMRT plans, on the other hand, were successful in dramatically lowering the levels of Dmax that reached the spinal cord for both right- and left-sided breast cancers.

CONCLUSION

Apart from similar planning target volume (PTV) coverage to IMRT plans, VMAT produced significantly better conformity. VMAT plans have more low-dose spillage to normal tissues, while IMRT plans spare various organs at risk significantly better at lower doses in both right and left-sided breast cancer. VMAT was found to be better at sparing the heart (in left-sided breast cancer only) and ipsilateral lung at a high dose range. The best radiotherapy approach for breast cancer should be established on an individual basis, taking into account tumor laterality and the risk-benefit ratio.

Normal Tissue Integral Dose as a Result of Prostate Radiation Therapy: A Quantitative Comparison Between High-Dose-Rate Brachytherapy and Modern External Beam Radiation Therapy Techniques

Purpose

Quantification of integral radiation dose delivered during treatment for prostate cancer is lacking. We performed a comparative quantification of dose to nontarget body tissues delivered via 4 common radiation techniques: conventional volumetric modulated arc therapy, stereotactic body radiation therapy, pencil-beam scanning proton therapy, and high-dose-rate brachytherapy.

Methods and Materials

Plans for each radiation technique were generated for 10 patients with typical anatomy. For brachytherapy plans, virtual needles were placed to achieve standard dosimetry. Standard planning target volume margins or robustness margins were applied as appropriate. A "normal tissue" structure (entire computed tomography simulation volume minus planning target volume) was generated for integral dose computation. Dose-volume histogram parameters for targets and normal structures were tabulated. Normal tissue integral dose was calculated by multiplying normal tissue volume by mean dose.

Results

Normal tissue integral dose was lowest for brachytherapy. Pencil-beam scanning protons, stereotactic body radiation therapy, and brachytherapy resulted in 17%, 57%, and 91% absolute reductions compared with standard volumetric modulated arc therapy, respectively. Mean nontarget tissues receiving 25%, 50%, and 75% of the prescription dose were reduced by 85%, 76%, and 83% for brachytherapy relative to volumetric modulated arc therapy, by 79%, 64%, and 74% relative to stereotactic body radiation therapy, and 73%, 60%, and 81% relative to proton therapy. All reductions observed using brachytherapy were statistically significant.

Conclusions

High-dose-rate brachytherapy is an effective technique for reducing dose to nontarget body tissues relative to volumetric modulated arc therapy, stereotactic body radiation therapy, and pencil-beam scanning proton therapy.

Impact of Advanced External Beam Radiotherapy on Second Haematological Cancer Risk in Prostate Cancer Survivors

AIMS

External beam radiotherapy (EBRT) for prostate cancer (PCa) has rapidly advanced over the years. Advanced techniques with altered dose distributions may have an impact on second haematological cancer (SHC) risks. We assessed SHC risk after EBRT for PCa and explored whether this risk has changed over the years.

MATERIALS AND METHODS

Patients diagnosed with a T1-T3 PCa between 1990 and 2015 were selected from the Netherlands Cancer Registry. Patients treated with EBRT were assigned to EBRT eras based on the date of diagnosis. These eras represented two-dimensional radiotherapy (2D-RT; 1991-1996), three-dimensional conformal radiotherapy (3D-CRT; 1998-2005) or advanced EBRT (2008-2015). Standardised incidence ratios (SIR) and absolute excess risks (AER) were calculated overall and by EBRT era. Sub-hazard ratios (sHRs) were calculated for the comparison of EBRT versus radical prostatectomy and active surveillance.

RESULTS

PCa patients with EBRT as the primary treatment (n = 37 762) had an increased risk of developing a SHC (SIR = 1.20; 95% confidence interval 1.13-1.28) compared with the Dutch male general population. Estimated risks were highest for the 2D-RT era (SIR = 1.32; 95% confidence interval 1.14-1.67) compared with the 3D-CRT era (SIR = 1.16; 95% confidence interval 1.05-1.27) and the advanced EBRT era (SIR = 1.21; 95% confidence interval 1.07-1.36). AER were limited, with about five to six extra cases per 10 000 person-years. Relative risk analysis (EBRT versus radical prostatectomy/active surveillance) showed significant elevation with EBRT versus active surveillance (sHR = 1.17; 95% confidence interval 1.03-1.33; P = 0.017), but not for EBRT versus radical prostatectomy (sHR = 1.08; 95% confidence interval 0.94-1.23; P = 0.281).

CONCLUSION

Increased SHC risks after EBRT for PCa cancer were observed for all EBRT eras compared with the general Dutch male population. Excess risks for EBRT versus other PCa treatment groups were found for only EBRT versus active surveillance.

Advances in radiotherapy and its impact on second primary cancer risk: a multi-center cohort study in prostate cancer patients

BACKGROUND

Modelling studies suggest that advanced intensity-modulated radiotherapy may increase second primary cancer (SPC) risks, due to increased radiation exposure of tissues located outside the treatment fields. In the current study we investigated the association between SPC risks and characteristics of applied external beam radiotherapy (EBRT) protocols for localized prostate cancer (PCa).

METHODS

We collected EBRT protocol characteristics (2000-2016) from five Dutch RT institutes for the 3D-CRT and advanced EBRT era (N=7908). From the Netherlands Cancer Registry we obtained patient/tumour characteristics, SPC data, and survival information. Standardized incidence ratios (SIR) were calculated for pelvis and non-pelvis SPC. Nationwide SIRs were calculated as a reference, using calendar period as a proxy to label 3D-CRT/advanced EBRT.

RESULTS

From 2000-2006, 3D-CRT with 68-78 Gy in 2 Gy fractions, delivered with 10-23 MV and weekly portal imaging was the most dominant protocol. By the year 2010 all institutes routinely used advanced EBRT (IMRT, VMAT, tomotherapy), mainly delivering 78 Gy in 2Gy fractions, using various kV/MV imaging protocols. Sixteen percent (N=1268) developed ≥1 SPC. SIRs for pelvis and non-pelvis SPC (all institutes, advanced EBRT vs 3D-CRT) were 1.17 (1.00-1.36) vs 1.39 (1.21-1.59), and 1.01 (0.89-1.07) vs 1.03 (0.94-1.13), respectively. Nationwide non-pelvis SIR was 1.07 (1.01-1.13) vs 1.02 (0.98-1.07). Other RT protocol characteristics did not correlate with SPC endpoints.

CONCLUSION

None of the studied RT characteristics of advanced EBRT was associated with increased out-of-field SPC risks. With constantly evolving EBRT protocols, evaluation of associated SPC risks remains important.

Hypofractionated whole breast irradiation with simultaneous integrated boost in breast cancer using helical tomotherapy with or without regional nodal irradiation: A report of acute toxicities

Purpose

We prospectively investigated the acute toxicities focusing on skin and hematologic function in breast cancer patients who received hypofractionated whole breast irradiation with simultaneous integrated boost (HF-WBI-SIB) with helical tomotherapy (HT), with or without regional nodal irradiation (RNI).

Methods

The dose of WBI and RNI was 42.4 Gy in 16 fractions. Tumor bed was prescribed to 49.6 Gy in 16 fractions simultaneously. The association between the worst grade of acute toxicities during treatment and receiving RNI was analyzed. The integral dose to the whole body between the two groups was also compared.

Results

Between May 2021 and May 2022, 85 patients were enrolled; 61 patients received HF-WBI-SIB only (71.8%) and 24 patients (28.2%) received HF-WBI-SIB with RNI. Grade 2 acute skin toxicity was found in 1.2%. The most frequent grade 2 or more hematologic toxicity was leukopenia, which occurred in 4.8% and 11% in the 2nd and 3rd week, respectively. Mean whole body integral dose was significantly higher in patients treated with RNI compared to patients treated without RNI: 162.8 ± 32.8 vs. 120.3 ± 34.7 Gy-L (p-value &lt; 0.001). There was no statistically significant difference in acute grade 2 or more skin and hematologic toxicities between the two groups.

Conclusions

HF-WBI-SIB with or without RNI is feasible with acceptable acute skin and hematologic toxicities. RNI and whole body integral dose were not associated with these acute toxicities.

Cardiac dose in the treatment of synchronous bilateral breast cancer patients between three different radiotherapy techniques (VMAT, IMRT, and 3D CRT)

PURPOSE

Synchronous bilateral irradiation of both mammary glands and chest wall is a challenging task due to technical difficulties and limited evidence supporting an optimal technique to improve treatment outcomes. We studied and compared the dosimetry data of three radiotherapy techniques to select the most optimal one.

METHODS

We compared three-dimensional conformal radiation treatment (3D CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) during irradiation of synchronous bilateral breast cancer in nine patients followed by examination of dose distribution to the cardiac conduction system (SA node, AV node and Bundle of His), myocardium, lungs, left anterior descending artery (LADA) and right coronary artery (RCA) .

RESULTS

VMAT is the most sparing technique for SBBC treatment. Even though doses to the SA node, AV node and Bundle of His were higher with VMAT (D_mean were 3.75 ± 0.62, 2.58 ± 0.83 and 3.03 ± 1.18 Gy respectively) compared with 3D CRT (D_mean were 2.61 ± 0.66, 1.52 ± 0.38 and 1.88 ± 0.70 Gy respectively), this difference is statistically insignificant. Doses to the right and left lung (average D_mean = 12.65 ± 3.20 Gy, V_20Gy = 24.12 ± 6.25%), myocardium (D_mean = 5.33 ± 1.51 Gy, V_10Gy = 9.80 ± 3.83%, V_20Gy = 7.19 ± 3.15%, V_25Gy = 6.20 ± 2.93%), and LADA (D_mean = 10.04 ± 4.92 Gy, V_20Gy = 18.17 ± 13.24% and V_25Gy = 15.41 ± 12.19%) were highest with 3D CRT. The highest  D_mean in the cardiac conduction system (5.30 ± 2.23, 3.15 ± 1.61 and 3.89 ± 1.85 Gy respectively) was observed with IMRT, and a similar effect was noted in RCA (D_mean = 7.48 ± 2.11 Gy).

CONCLUSION

VMAT is the optimal and satisfactory radiation therapy technique for sparing organs at risk (OARs). With VMAT, a lower D_mean value was noted in the myocardium, LADA, and lungs. The use of 3D CRT significantly increases the dose of radiation reaching the lungs, myocardium, and LADA, which can subsequently cause cardiovascular and lung complications, but not in the cardiac conduction system.

The effect of primary tumor volume on the prognosis of nasopharyngeal carcinoma in era of volumetric modulated arc therapy: a propensity score matched cohort study

OBJECTIVE

The role of Primary Tumor Volume (PTV) in Nasopharyngeal Carcinoma (NPC) treated with Volumetric Modulated Arc Therapy (VMAT) is still unclear. The aim of this study was to access the effect of PTV in prognosis prediction of nasopharyngeal carcinoma in era of VMAT.

METHODS

Between January 20 and November 2011, 498 consecutive NPC patients with stage I-IVA disease who received VMAT at a single center were retrospectively analyzed. Receiver Operating Characteristic (ROC) was performed to access the cut-off point of PTV. Univariate Kaplan-Meier and multivariate Cox regression analyses were used to evaluate prognostic value for PTV. The Propensity Score Matching (PSM) was used to adjust baseline potential confounders.

RESULTS

The 5-year Locol-Regional Failure-Free (L-FFR), Distant Failure-Free Survival (D-FFR), Disease-Free Survival (DFS) and Overall Survival (OS) were 90.6%, 83.7%, 71.5% and 79.3%, respectively. Before PSM, the 5-year L-FFR, D-FFR, DFS, OS rates for NPC patients with PTV ≤ 38 mL vs. PTV > 38 mL were 94.1% vs. 90.4% (p = 0.063), 87.9% vs. 76.3% (p < 0.001), 78.5% vs. 58.5% (p < 0.001) and 86.3% vs. 66.7% (p < 0.001) respectively. Multivariate analysis showed PTV was an independent prognostic factor for D-FFS (p = 0.034), DFS (p = 0.002) and OS (p = 0.001). PTV classified was still an independent prognostic factor for OS after PSM (HR = 2.034, p = 0.025.

CONCLUSIONS

PTV had a substantial impact on the prognosis of NPC patients treated with VMAT before and after PSM simultaneously. PTV > 38 mL may be considered as an indicator of the clinical stage of nasopharyngeal carcinoma.

LEVEL OF EVIDENCE

III.

Case report: Identification of acute promyelocytic leukemia during osimertinib resistance followed by granulocyte colony-stimulating factor and pembrolizumab

Background

The occurrence of acute promyelocytic leukemia (APL) during the management of lung cancer is rare and life-threatening. It was mainly reported to be secondary to chemoradiotherapy. A few studies reported an increased incidence of therapy-related acute promyelocytic leukemia (t-APL) after gefitinib became available.

Case presentation

We reported a patient who developed thrombocytopenia after receiving oral osimertinib in combination with intensity-modulated radiotherapy (IMRT). For half a year, she had an unrecoverable low platelet count, which progressed to concomitant leukopenia and the transient appearance of orthochromatic normoblasts in the peripheral blood test, indicating a dormant myeloid disorder. Due to simultaneous resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI), pembrolizumab and granulocyte colony-stimulating factor (G-CSF) were administered, revealing prominent signs of hematological malignancy in a peripheral blood test that was later identified as t-APL.

Conclusion

In general, patients undergoing EGFR-TKI combined with local radiotherapy should be concerned about their hematological assessment. If patients exhibit unrecoverable abnormalities in routine blood tests, a secondary nonsolid malignancy other than myelosuppression should be considered, and further lung cancer treatment should be discontinued.

Post-irradiation sarcoma after definitive radiation therapy for nasopharyngeal carcinoma

BACKGROUND AND PURPOSE

Postirradiation sarcoma (PIS) is a rare radiation-induced malignancy after nasopharyngeal carcinoma (NPC) treatment.

MATERIALS AND METHODS

We retrospectively screened 9,185 NPC patients between 2000 and 2020 and identified 41 patients with PIS according to the modified Cahan's criteria: (1) the PIS must have arisen within a previous radiation field; (2) a latent period must have existed; (3) histologically proved sarcoma; (4) the tissue in which the PIS arose must have been healthy prior to the radiation. The initial radiation therapy techniques used were 2D (25; 61.0%), 3D (7; 17.1%), and IMRT (9; 22%).

RESULTS

The time (year) from radiotherapy (RT) to PIS was longer when using 2D or 3D irradiation techniques (median, 14.2; range, 3.4-28.1; Q1-Q3, 8.6-19.7) than when using IMRT (median, 6.6; range, 3.8-15.7; Q1-Q3, 4.5-11.7; P =.026). The time (year) from RT to PIS diagnosis was significantly longer when using lower radiation energy from cobalt-60 (median, 15.8; range, 10.4-28.4; Q1-Q3, 12.5-23.8) than when using a higher radiation energy of 6 or 10 MV (median, 10.2; range, 3.4-23.3; Q1-Q3, 6.5-16.1; P =.006). The 2-year overall survival rates for patients who underwent surgery, radical radiotherapy, systemic therapy alone and no treatment were 60.7 %, 42.9 %, 0 % and 0 %, respectively (P =.000). Of the 3 retrievable initial RT dosimetry plans for NPC, the D95 values (dose that covers 95 % of the PIS volume) for PIS were 6267, 6344 and 5820 cGy, respectively.

CONCLUSION

High radiation energy and modern techniques may shorten NPC PIS latency. Surgery may be associated with improved survival if feasible.

Multiple primary head and neck squamous cell cancer: Lessons learnt

AIM

To analyze the demographic profile, treatment outcome, and factors affecting them in multiple primary head and neck squamous cell cancer (MPHNSCC) patients.

MATERIALS AND METHODS

Hospital case records of patients with histopathology proven MPHNSCC registered in the radiation oncology department from January 2008 to December 2020 were retrospectively studied. Modified Warren-Gates criteria were used to define MPHNSCC. Demographic and clinical details were recorded and analyzed.

RESULTS

Twenty-seven patients had histopathology proven MPHNSCC. The median age at diagnosis of an index case was 50 years (minimum 26, maximum 70) with a male to female sex ratio of 22:5. Seventeen (62.96%) patients were tobacco users; either smoked or smokeless. The oral cavity was the commonest sub-site for both an index and second primary malignancy (22 patients; 81.48%) and the majority presented in a locally advanced stage of disease (10; 37.03% and 16; 62.95% for an index and second primary, respectively). The presentation was simultaneous, synchronous, and metachronous in 1 (3.7%), 2 (7.4%), and 24 (88.89%) patients, respectively. Two patients had three sites of MPHNSCC. The average duration of chronicity was 54.37 months (min. 8 and max. 156). MPHNSCC were ipsilateral in 10 (37.04%) patients and re-irradiation was planned for 22 (81.48%) patients with 50% treatment compliance. At the time of the last hospital visit, 18 (66.66%) patients were alive with disease, 7 (25.92%) patients were alive without disease, and 2 (7.40%) patients died of disease.

CONCLUSION

A higher percentage of MPHNSCC originated from the oral cavity and the majority presented in the locally advanced stage of disease; despite the site being accessible to self-oral examination. Patient education and physician's awareness regarding the MPHNSCC are needed.

The use of Hybrid Techniques in Whole-Breast Radiotherapy: A Systematic Review

Objectives The development of new techniques in radiotherapy (RT) provides a better planned target volume (PTV) dose distribution while further improving the protection of organs at risk (OARs). The study aims to present the dosimetric results of studies using hybrid techniques in whole-breast radiotherapy (WBRT). Methods: This systematic literature review was conducted by scanning the relevant literature in PubMed, Scopus, and Web of Science following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Among the parameters are dose values for PTV and OARs beam contribute ratios, the value of monitors, and treatment times for different RT techniques. Initially, 586 articles were identified; 196 duplicate articles were removed leaving 391 articles for screening. Three-hundred and thirty-seven irrelevant articles were excluded, leaving 54 studies assessed for eligibility. A total of 22 articles met the search criteria to evaluate dosimetric results of hybrid and other RT techniques in WBRT. Results: According to the dosimetric data of the studies, hybrid intensity-modulated RT (H-IMRT) and hybrid volumetric-modulated arc therapy (H-VMAT) techniques give dosimetrically advantageous results in WBRT compared to other RT techniques. Conclusion: Hybrid techniques using appropriate beams contribute value and show great promise in improving dosimetric results in WBRT. However, there is a need for new studies showing the long-term clinical results of hybrid RT.

Radiation-induced soft tissue sarcoma of the neck after radiation therapy for Hodgkin's lymphoma: a clinical case

Background. Radiation-induced malignancies are one of the long-term complications of radiation therapy, which is widely used to treat some tumors. The latency period before a second tumor develops varies from 3 to 60 years. Epithelial tumors and hemoblastoses occur after low-dose radiation therapy and sarcomas after high-dose radiation therapy. Aim. To present a case of radiation-induced soft tissue angiosarcoma of the neck after the cure of Hodgkin's disease. Materials and methods. A 41-year-old patient with Hodgkin's nodular lymphoma with the lymphoid predominance of stage IIIA with involvement of the right cervical and clavicular lymph nodes, mediastinum, and abdominal lymph nodes was followed-up. In 2004 the patient underwent four cycles of polychemotherapy per ABVD regimen followed by radiotherapy of the right cervical and clavicular lymph nodes and mediastinum, with a total focal dose of 40 Gy. Results. Seventeen years after the treatment for Hodgkin's disease, including radiation therapy, the patient presented with painful swelling of the neck soft tissues in the radiation area with the transition to the anterior thoracic wall and an enlarged cervical lymph node. A lymph node dissection was performed. According to the combined positron emission tomography and X-ray computed tomography (PET/CT), histological and immunohistochemical studies, epithelioid angiosarcoma of soft tissues of the neck and thoracic wall stage IV cT2N1M1G3 with metastases to the skeleton bones, neck lymph nodes, left adrenal gland was established. Surgical treatment was not performed due to advanced disease. The patient received six cycles of polychemotherapy with doxorubicin + ifosfamide. PET/CT confirmed partial tumor regression. Conclusion. Radiation-induced soft tissue sarcoma is a late iatrogenic complication of radiation therapy for Hodgkin's lymphoma. The tumor occurred in the radiation area. PET/CT is the method of choice in diagnosing and evaluating the extent of cancer and response to treatment. Chemotherapy, as an option for complex treatment, can achieve adequate disease control when surgery is not feasible.

VMAT partial arc technique decreases dose to organs at risk in whole pelvic radiotherapy for prostate cancer when compared to full arc VMAT and IMRT

Whole pelvic radiotherapy (WPRT) can sterilize microscopic lymph node metastases in treatment of prostate cancer. WPRT, compared to prostate only radiotherapy (PORT), is associated with increased acute gastrointestinal, and hematological toxicities. To further explore minimizing normal tissue toxicities associated with WPRT in definitive IMRT for prostate cancer, this planning study compared dosimetric differences between static 9-field-IMRT, full arc VMAT, and mixed partial-full arc VMAT techniques. In this retrospective study, 12 prostate cancer patients who met the criteria for WPRT were randomly selected for this study. The initial volume, PTV46, included the prostate, seminal vesicles, and pelvic nodes with margin and was prescribed to 4600 cGy. The cone-down volume, PTV78, included the prostate and proximal seminal vesicles with margin to a total dose of 7800 cGy. For each CT image set, 3 plans were generated for each of the PTVs: an IMRT plan, a full arc (FA) VMAT plan, and a mixed partial-full arc (PFA) VMAT plan, using 6MV photons energy. According to RTOG protocols none of the plans had a major Conformity Index (CI) violation by any of the 3 planning techniques. PFA plan had the best mean CI index of 1.00 and significantly better than IMRT (p = 0.03) and FA (p = 0.007). For equivalent PTV coverage, the average composite gradient index of the PFA plans was better than the IMRT and the FA plans with values 1.92, 2.03, and 2.01 respectively. The defference was statistically significant between PFA/IMRT and PFA/FA, with p- values of < 0.001. The IMRT plans and the PFA plans provided very similar doses to the rectum, bladder, sigmoid colon, and femoral heads, which were lower than the dose in the FA plans. There was a significant decrease in the mean dose to the rectum from 4524 cGy with the FA to 4182 cGy with the PFA and 4091 cGy with IMRT (p < 0.001). The percent of rectum receiving 4000 cGy was also the highest with FA at 66.1% compared to 49.9% (PFA) and 47.5% (IMRT). There was a significant decrease in the mean dose to the bladder from 3922 cGy (FA) to 3551 cGy (PFA) and 3612 cGy (IMRT) (p < 0.001). The percent of bladder receiving 4000 cGy was also the highest with FA at 45.4% compared to 36.6% (PFA) and 37.4% (IMRT). The average mean dose to the sigmoid colon decreased from 4177 cGy (FA) to 3893 cGy (PFA) and 3819 cGy (IMRT). The average mean dose to the femoral heads decreased from 2091 cGy (FA) to 2026 cGy (PFA) and 1987 cGy (IMRT). Considering the improvement in plan quality indices recorded in this study including the dose gradient and the dose to organs at risk, mixed partial-full arc plans may be the preferred VMAT treatment technique over full arc plans for prostate cancer treatments that include nodal volumes.

On the effectiveness of proton boron fusion therapy (PBFT) at cellular level

The present work introduced a framework to investigate the effectiveness of proton boron fusion therapy (PBFT) at the cellular level. The framework consisted of a cell array generator program coupled with PHITS Monte Carlo package with a dedicated terminal-based code editor that was developed in this work. The framework enabled users to model large cell arrays with normal, all boron, and random boron filled cytoplasm, to investigate the underlying mechanism of PBFT. It was found that alpha particles and neutrons could be produced in absence of boron mainly because of nuclear reaction induced by proton interaction with ¹⁶O, ¹²C and ¹⁴N nuclei. The effectiveness of PBFT is highly dependent on the incident proton energy, source size, cell array size, buffer medium thickness layer, concentration and distribution of boron in the cell array. To quantitatively assess the effectiveness of PBFT, of the total energy deposition by alpha particle for different cases were determined. The number of alpha particle hits in cell cytoplasm and nucleus for normal and 100 ppm boron were determined. The obtained results and the developed tools would be useful for future development of PBFT to objectively determine the effectiveness of this treatment modality.

Dosimetric evaluation of VMAT and helical tomotherapy techniques comparing conventional volumes with clinical target volumes based on new ESTRO ACROP post-mastectomy with immediate implant reconstruction contouring guidelines

Background

The ESTRO-ACROP Consensus Guideline (EACG) recommends implant excluded clinical target volume (CTVp) definitions for post-mastectomy radiation therapy after implant-based immediate breast reconstruction (IBR). The purpose of this study is to investigate the effectiveness of Helical Tomotherapy (HTp) and Volumetric Modulated Arc Therapy (VMATp) treatment techniques in terms of CTVp coverage and reduced organ at risk (OAR), normal tissue and implant doses when CTVp was used for treatment planning as the target structure instead of conventional CTV.

Methods

Eight left-sided and eight right-sided breast cancer patients who underwent IBR after mastectomy were included in this study. Planning CT data sets were acquired during free breathing and patients were treated with HT technique targeted to conventional CTV. Retrospectively, CTVp was delineated based on EACG by the same radiation oncologist, and treatment plans with HTp and VMATp techniques were generated based on CTVp. For each patient, relevant dosimetric parameters were obtained from three different treatment plans.

Results

There was no statistically significant difference on target coverage in terms of, PTVp-D95, PTVp-Vpres, homogeneity index (p > 0.05) between HTp and VMATp plans. But, the conformity numbers were significantly higher (HTp vs VMATp, 0.69 ± 0.15 vs 0.79 ± 0.12) for VMATp (Z = − 2.17, p = 0.030). While HTp significantly lowered Dmax and Dmean for LAD (LAD-D_max: χ² = 12.25, p = 0.002 and LAD-D_mean: χ² = 12.30, p = 0.002), neither HTp nor VMATp could reduce maximum and mean dose to heart (p > 0.05). Furthermore, heart volume receiving 5 Gy was significantly higher for VMATp when compared to HTp (21.2 ± 9.8 vs 42.7 ± 24.8, p: 0.004). Both techniques succeeded in reducing the mean dose to implant (HTp vs HT, p < 0.001; VMATp vs HT, p < 0.001; VMATp vs HTp, p = 0.005).

Conclusion

Both HTp and VMATp techniques succeeded to obtain conformal and homogeneous dose distributions within CTVp while reducing the mean implant dose. HTp was found to be superior to VMATp with regards to lowering all OAR doses except for CB.

A simple analytical model for a fast 3D assessment of peripheral photon dose during coplanar isocentric photon radiotherapy

Considering that cancer survival rates have been growing and that nearly two-thirds of those survivors were exposed to clinical radiation during its treatment, the study of long-term radiation effects, especially secondary cancer induction, has become increasingly important. To correctly assess this risk, knowing the dose to out-of-field organs is essential. As it has been reported, commercial treatment planning systems do not accurately calculate the dose far away from the border of the field; analytical dose estimation models may help this purpose. In this work, the development and validation of a new three-dimensional (3D) analytical model to assess the photon peripheral dose during radiotherapy is presented. It needs only two treatment-specific input parameter values, plus information about the linac-specific leakage, when available. It is easy to use and generates 3D whole-body dose distributions and, particularly, the dose to out-of-field organs (as dose–volume histograms) outside the 5% isodose for any isocentric treatment using coplanar beams [including intensity modulated radiotherapy and volumetric modulated arc therapy (VMAT)]. The model was configured with the corresponding Monte Carlo simulation of the peripheral absorbed dose for a 6 MV abdomen treatment on the International Comission on Radiological Protection (ICRP) 110 computational phantom. It was then validated with experimental measurements using thermoluminescent dosimeters in the male ATOM anthropomorphic phantom irradiated with a VMAT treatment for prostate cancer. Additionally, its performance was challenged by applying it to a lung radiotherapy treatment very different from the one used for training. The model agreed well with measurements and simulated dose values. A graphical user interface was developed as a first step to making this work more approachable to a daily clinical application.

Does Fluence Smoothing Reduce the Complexity of the Intensity-Modulated Radiation Therapy Treatment Plan? A Dosimetric Analysis

Background

Intensity-modulated radiation therapy (IMRT) may have too many peaks and valleys, making the treatment plan undeliverable. When there are too many fluency differences between adjacent pixels in the X or Y directions, the X and Y smoothing factors are utilized as weighting factors to penalize this behavior. Generally, a high degree of complexity is accompanied by many monitor units (MUs), large number of segments, small sized segments, and complex segment shapes. The degree of plan delivery uncertainty can all increase with a higher detailed fluence map.

Aim

This study aims to evaluate the dosimetric effects of various smoothing levels on the planning target volume (PTV) and organs at risk (OARs) for cervix cancer.

Materials and Methods

IMRT treatment plans were re-optimized by combining several values of the X and Y penalty between 0 and 100. The dose-volume histogram assessed various dosimetric indicators for PTV and OARs. Additionally, gamma passing rates were evaluated and noted as an indicator of the complex treatment plan.

Results

At X = 60, Y = 60 fluence map penalty, the conformity index (CI) value reached its highest value of 0.996 ± 0.004. At X = 0, Y = 0, the homogeneity index (HI) was determined to have a maximum value of 0.0628 ± 0.0235. The highest and lowest MU values were 2424.30 ± 471.12 and 1087.80 ± 91.57, respectively, with X = 0, Y = 0 and X = 100, Y = 100. At X = 100, Y = 100, the gamma passing rate reaches its highest value of 99.28% ± 0.44% and minimum value of 85.93% ± 3.87% at X = 0, Y = 0.

Conclusion

The CI and HI values showed no discernible fluctuation, and the OAR doses were barely affected as smoothing was increased. When the smoothing factor was raised, the number of MUs sharply dropped, and a decrease in the number of segments and higher gamma passing rates were also seen.