Inverse planning in three-dimensional conformal and intensity-modulated radiotherapy of mid-thoracic oesophageal cancer

Knowledge domains and emerging trends in radiotherapy in oesophageal cancer from 2004 to 2023: a bibliometric analysis and visualization study

Esophageal cancer (EC) is a malignant tumour with high morbidity and mortality rates. Recent studies have shown that much progress has been made in the research of radiotherapy in EC. This study aims to provide a comprehensive overview of the knowledge structure and research hotspots of radiotherapy in EC through bibliometrics. Publications related to radiotherapy in EC from 2014 to 2023 were searched on the web of science core collection database. VOSviewers, CiteSpace and R package 'bibliometrix' were used to conduct this bibliometric analysis. In total, 4258 articles from 76 countries led by China and the USA were included. The Chinese Academy of Medical Sciences-Peking Union Medical College has the highest number of publications. International Journal of Radiation Oncology Biology Physics is the most popular journal and also the most co-cited journal in this field. These publications come from 21 972 authors among which Liao Zhongxing had published the most papers and Cooper JS was co-cited most often. Neoadjuvant chemoradiotherapy and strategies based on it are the main topics in this research field. 'IMRT' and 'immunotherapy' are the primary keywords of emerging research hotspots. This is a bibliometric study that comprehensively summarizes the research trends and developments of radiotherapy in EC. This information identifies recent research frontiers and hot directions, which will provide a reference for scholars studying radiotherapy in EC.

Proton Beam Therapy for Esophageal Cancer

Simple Summary

Early-stage esophageal cancer is managed surgically, with the addition of radiotherapy for locally advanced disease. Current photon-based radiotherapy results in a high treatment-related complications, due to proximal organ involvement. The anatomic location of the esophagus raises challenges due to the anatomical changes associated with diaphragmatic motion, weight loss, tumor changes, and set-up variability. These propelled the interest in proton beam therapy (PBT), which theoretically offers a reduction in the radiation exposure to healthy neighboring tissues with improvements in the therapeutic ratio. In this review, we present the role of PBT for esophageal cancer, including treatment planning, early clinical comparisons with photon-based techniques, ongoing trials, current challenges, toxicities, and issues of equity and health services.

Abstract

Early-stage esophageal cancer is often primarily managed surgically, with the addition of radiotherapy for locally advanced disease. However, current photon-based radiotherapy regimens and surgery results in a high incidence of treatment-related cardiac and pulmonary complications due to the involvement of proximal organs at risk. In addition, the anatomic location of the esophagus raises challenges for radiotherapy due to the anatomical changes associated with diaphragmatic motion, weight loss, tumor changes, and set-up variability. These challenges propelled the interest in proton beam therapy (PBT), which theoretically offers a reduction in the radiation exposure to healthy neighboring tissues with improvements in the therapeutic ratio. Several dosimetric studies support the potential advantages of PBT for esophageal cancer treatment however, translation of these results to improved clinical outcomes remains unclear with limited clinical data, especially in large populations. Studies on the effect on quality of life are likewise lacking. Here, we review the existing and emerging role of PBT for esophageal cancer, including treatment planning, early clinical comparisons of PBT with photon-based techniques, recently concluded and ongoing clinical trials, challenges and toxicities, effects on quality of life, and global inequities in the treatment of esophageal cancer.

Photon Versus Proton Beam Therapy for T1-3 Squamous Cell Carcinoma of the Thoracic Esophagus Without Lymph Node Metastasis

Background and Purpose

We compared treatment outcomes and toxicities of photon radiotherapy versus proton beam therapy (PBT) and evaluated radiation field effects for T1–3 squamous cell carcinoma of the thoracic esophagus (EC) without lymph node metastasis.

Methods

Medical records of 77 patients with T1–3N0M0 thoracic EC treated with radiotherapy between 2011 and 2019 were retrospectively analyzed. Among these patients, 61 (79.2%) individuals had T1 EC. The initial clinical target volume encompassed the whole esophagus with or without supraclavicular and/or abdominal lymph nodes (extended-field radiotherapy; 67 patients, 87.0%) or the area 3–5 cm craniocaudally and 1–2 cm radially from the gross tumor volume (involved-field radiotherapy; 10 patients, 13.0%). The final clinical target volume included margins of at least 1 cm from the gross tumor volume, with total radiation doses of 50–66 (median, 66) cobalt gray equivalent. Three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and PBT were used in twenty-four, five, and forty-eight patients, respectively. Concurrent chemotherapy was administered to 17 (22.0%) patients overall and only five (8.0%) T1 patients.

Results

PBT showed significantly lower lung and heart radiation exposure in mean dose, V5, V10, V20, and V30 than photon radiotherapy. The median follow-up for all patients was 46 (interquartile range, 22–72) months. The 5-year progression-free survival and overall survival rates were 56.5 and 64.9%, respectively, with no significant survival difference between photon radiotherapy and PBT. In patients with T1 EC, 5-year progression-free survival and overall survival rates were 62.6 and 73.5%, respectively.

Conclusions

Extended-field radiotherapy using modern radiotherapy techniques without chemotherapy showed satisfactory clinical outcomes for lymph node-negative T1 EC.

A novel inverse optimization based three-dimensional conformal radiotherapy technique in craniospinal irradiation

Our aim was to develop a novel inverse optimization-based three-dimensional conformal radiotherapy (i3DCRT) technique for craniospinal irradiation. The imaging data of 20 patients with medulloblastoma were used retrospectively. The first group included 10 pediatric patients with supine position treated under anesthesia/sedation, and the second group included 10 young adult/adult patients treated with prone position. Three different treatment plans were created for each patient via i3DCRT, forward-planned three-dimensional conformal radiotherapy (f3DCRT) and intensity-modulated radiotherapy (IMRT) techniques. A total dose of 36 Gy was prescribed in 20 fractions for all plans. The comparative evaluation was conducted by using the parameters of conformity-index, homogeneity-index, and doses to the target volumes and organs at risk (OARs). The plans created with i3DCRT technique achieved better conformity and homogeneity compared to f3DCRT. In terms of OARs sparing, we found pronounced dose reductions in esophagus and heart in i3DCRT compared to f3DCRT plans. i3DCRT technique also provided a well-conformed dose distribution not superior, but comparable, to IMRT without increase in the total monitor unit per fraction (MU/fx) with respect to f3DCRT. The average monitor unit per fraction (MU/fx) for i3DCRT, f3DCRT and IMRT plans were found as 379.3, 378.0 and 1051.7 MU for the first group and 577.4, 563.5 and 1368.7 MU for the second group, respectively. Novel i3DCRT technique solves the problems associated with field junctions and beam edge matching encountered in f3DCRT plans. Additionally, i3DCRT technique can create almost similar plans as with IMRT with lower total MU/fx.

Definitive radiotherapy dose escalation with chemotherapy for treating non-metastatic oesophageal cancer

The locoregional failure rate remains high after concurrent chemoradiotherapy with standard-dose radiotherapy (RT, 50–50.4 Gy) for oesophageal cancer (EC). This retrospective study evaluated whether RT dose escalation was effective among 115 consecutive patients with non-metastatic EC (July 2003 to November 2016). Forty-four patients received an RT dose of <66 Gy and 71 patients received ≥66 Gy, with most patients receiving concurrent cisplatin plus fluorouracil. The median follow-up was 12 months for all patients (52 months for 18 surviving patients). The ≥66 Gy group had significantly higher 3-year rates of overall survival (17.9% vs. 32.1%, p = 0.026) and local progression-free survival (46.1% vs. 72.1%, p = 0.005), but not disease progression-free survival (11.4% vs. 21.9%, p = 0.059) and distant metastasis-free survival (49% vs. 52.6%, p = 0.852). The ≥66 Gy group also had significantly better 5-year overall survival compared with 41.4–65.9 Gy. The only significant difference in treatment-related toxicities involved acute dermatitis (7% vs. 28%, p = 0.009). Inferior overall survival was associated with poor performance status, clinical N2–3 stage and not receiving maintenance chemotherapy. In conclusion, patients with inoperable EC experienced better survival outcomes and acceptable toxicities if they received higher dose RT (≥66 Gy) rather than lower dose RT (<66 Gy).

Endoscopic resection with adjuvant chemo-radiotherapy for superficial esophageal squamous cell carcinoma: A critical review

Radical esophagectomy with extended lymph node dissection is considered the standard of care in treatment of squamous cell carcinoma of esophagus with deep mucosal invasion (pT1a m3) or submucosal involvement (pT1b). However, despite the increasing use of minimally invasive approaches, it remains a major surgery associated with significant morbidities and even mortality risk. Endoscopic resection (ER) results in excellent local control in early superficial mucosal (pT1a) disease yet there is substantial risk of lymph node metastases in T1b disease. Therefore, ER followed by combined with chemo-radiotherapy (CRT) would potentially improve the outcome in pT1a m3 or pT1b disease and would be an attractive conservative alternative to esophagectomy. Retrospective series published so far have shown promising results for this combined treatment. Herein the current literature of the indications, treatment outcome and toxicities of this treatment strategy are discussed and critically reviewed.

Setup errors in radiation therapy for thoracic tumor patients of different body mass index

Purpose

To assess the setup errors in radiation therapy for thoracic tumors patients of different somatotypes, and to seek an individualized mathematical basis for defining the planning target volume (PTV).

Methods

Sixty patients with thoracic tumors were divided into four somatotypes according to their body mass index (BMI), and their body positions were setup by two groups of technicians independently. CT simulations were performed and the reconstructed radiography was digitally generated as reference images for location verification and error measurement. By setting positioning error ranges, the within‐range positioning correction rate was compared among groups.

Results

Position setups for patients in the emaciated group, moderate group, and overweight group were relatively stable (with minor setup error differences between the two groups of technicians). In emaciated group, moderate group, overweight group, and obese group, setup errors in the right–left direction (R‐L) were 2.2 ± 1.3 mm, 2.2 ± 1.6 mm, 3.9 ± 3.1 mm, and 8.8 ± 3.5 mm, respectively; whereas the setup errors in the four groups in the superior–inferior(S‐I) direction were 2.4 ± 1.8 mm, 2.1 ± 1.9 mm, 3.2 ± 2.6 mm, and 5.4 ± 3.5 mm, and in the anterior–posterior (A‐P) direction were 2.2 ± 1.7 mm, 1.9 ± 1.9 mm, 3.2 ± 2.9 mm, and 6.2 ± 4.2 mm, respectively. Moreover, in the moderate group, the positioning correction rate in the three directions (R‐L, S‐I, and A‐P) was 20%, 9%, 8% within the error range of 5–10 mm, and 3%, 0%, 1% with a more than 10 mm error range. However, in overweight group and obese group, the positioning correction rate in these three directions (also with a more than 10 mm error range) was 23%, 27%, 19% and 21%, 16%, 23%, respectively.

Conclusions

In radiation therapy for patients with thoracic tumors, the definition of PTV should be individualized. Meanwhile, with the increase in BMI, positioning correction rate has a tendency to rise too.

Intensity modulated radiation therapy in the treatment of esophageal cancer

Chemoradiation plays a core role in the definitive and preoperative management of esophageal cancer. Remarkable advances in technology now allow for the implementation of intensity modulated radiation therapy (IMRT) to minimize normal organ damage and to maximize coverage of tumorous targets. While IMRT is commonly accepted in the treatment of prostate and head and neck cancers, there have been clinical and dosimetric studies supporting the use of IMRT in esophagus cancer. In addition, the IMRT technique was recently enhanced by the availability of volumetric intensity modulated arc therapy (VMAT). VMAT may allow for faster delivery of IMRT with the advantage of normal organ protection compared to the stop-and-shoot IMRT, with faster delivery time and reduced monitor units. This review summarizes the use of chemoradiation in esophageal cancer, discusses current dosimetric data and clinical outcomes with the use of IMRT, and reviews IMRT as part of multi-modality treatment in esophageal cancer.

Advances in radiotherapy for esophageal cancer

Esophageal cancer is a common type of malignancy worldwide and usually requires multidisciplinary care. Radiotherapy plays an important part in management of the disease. During the past few years, researchers have made much progress about radiotherapy for esophageal cancer, which was revealed in every aspect of clinical practice. Neoadjuvant chemoradiotherapy remains the standard treatment for locally advanced esophageal cancer, whereas neoadjuvant chemotherapy appears to show less toxicities and non-inferior prognosis. What's more, definitive chemoradiotherapy could be an option for non-surgical candidates and good responders to chemoradiotherapy. Advances in radiation techniques result in higher conformity, homogeneity, more normal tissue sparing and less treatment time. Promising prognoses and less toxicities were also seen in advanced techniques. As radiation dose higher than 50 Gy obtains better local control and survival, simultaneously integrated boost is designed to increase primary tumor dosage and keep prophylactic dose to subclinical areas. Elective nodal irradiation brings about better local control but do not show advantages in survival compared with involved field irradiation (IFI). As a trend, more tolerable chemoradiotherapy regimen would be taken into account in dealing with elderly patients.

Recent advances in intensity modulated radiotherapy and proton therapy for esophageal cancer

INTRODUCTION

Radiotherapy is an important component of the standard of care for esophageal cancer. In the past decades, significant improvements in the planning and delivery of radiation techniques have led to better dose conformity to the target volume and improved normal tissue sparing. Areas covered: This review focuses on the advances in radiotherapy techniques and summarizes the availably dosimetric and clinical outcomes of intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy, proton therapy, and four-dimensional radiotherapy for esophageal cancer, and discusses the challenges and future development of proton therapy. Expert commentary: Although three-dimensional conformal radiotherapy is the standard radiotherapy technique in esophageal cancer, the retrospectively comparative studies strongly suggest that the dosimetric advantage of IMRT over three-dimensional conformal radiotherapy can translate into improved clinical outcomes, despite the lack of prospective randomized evidence. As a novel form of conventional IMRT technique, volumetric modulated arc therapy can produce equivalent or superior dosimetric quality with significantly higher treatment efficiency in esophageal cancer. Compared with photon therapy, proton therapy has the potential to achieve further clinical improvement due to their physical properties; however, prospective clinical data, long-term results, and cost-effectiveness are needed.

Long-term survival and toxicity outcomes of intensity modulated radiation therapy for the treatment of esophageal cancer: A large single-institutional cohort study

Purpose

In patients with esophageal cancer (EC), intensity modulated radiation therapy (IMRT) improves dose sparing to the heart and lung, with some evidence showing clinical benefit. Herein, we report our cumulative clinical experience with the use of IMRT for EC.

Methods and materials

This is a retrospective analysis of 587 patients with nonmetastatic EC who were treated consecutively with IMRT from January 2004 to June 30, 2013. All patients with stage I-IVA (American Joint Committee on Cancer 2002) received concurrent chemoradiation therapy either preoperatively or definitively. The Kaplan-Meier method was used to compute overall survival (OS) and locoregional recurrence-free survival and disease-free survival. The Common Terminology Criteria for Adverse Events, Version 4.0 were used to grade acute and subacute complications.

Results

The median radiation dose was 50.4 Gy in 28 daily fractions. As of July 2015, the median follow-up was 31.4 months (range, 2.9-130.7 months) for all patients and 61.8 months (range, 7.7-130.7 months) for survivors. The median OS was 38.9 months, and the 1-, 3-, and 5-year OS rates were 86.7%, 51.8%, and 41.2%, respectively. The 1-, 3-, and 5-year locoregional recurrence-free survival rates were 77.6%, 68.2%, and 66.1%, respectively, and the 1-, 3-, and 5-year disease-free survival rates were 58.6%, 43.7%, and 41.4%, respectively. Outcomes for both trimodality and bimodality treated patients were better than the outcomes reported in the literature. Eight patients (1.4%) experienced grade ≥3 pneumonitis, and 74 patients (13%) developed grade ≥3 esophagitis. For patients who underwent surgery, the most common postoperative complications were pneumonia (9.6%), anastomotic leakage (11.1%), and atrial fibrillation (12.5%).

Conclusions

This is the largest, single institutional study to date on the long-term outcomes of treatment with IMRT for EC. For photon-based radiation therapy, IMRT yields excellent outcomes and should be considered for the treatment of EC.

High dose radiation with chemotherapy followed by salvage esophagectomy among patients with locally advanced esophageal squamous cell carcinoma

Background

Locoregional failure is a major problem associated with chemoradiation treatment for squamous cell esophageal carcinoma. The aim of this study was to assess the feasibility, efficacy, and toxicity of preoperative radiation (dose > 50 Gy) with platinum‐based chemotherapy followed by esophagectomy in locally advanced squamous cell carcinoma.

Methods

Data of patients with cT2‐cT4 or node positive squamous cell carcinoma of the esophagus who received trimodality treatment between February 2006 and June 2015 were reviewed.

Results

Forty‐four patients were treated with intensity‐modulated radiation therapy, volumetric‐modulated arc therapy or three‐dimensional radiation therapy. The median radiation dose was 60 Gy. The average volume of the lungs receiving 10 Gy was 48.1%, 20 Gy was 24.5%, and the average mean lung dose was 14 Gy. After chemoradiation, R0 resection was achieved in 31 patients (71%). Patients who received >60 Gy had a higher pathologic complete remission rate than those in the lower dose group (59.1% vs. 36.4%). R0 resection and radiation dose >60 Gy were associated with better overall survival in Cox proportional hazards regression analysis. The median follow‐up duration was 22.4 months and median survival was 25.6 months. Two‐year overall, progression‐free survival and locoregional control rates were 55.9%, 28.6%, and 56%, respectively. The most common grade 3–4 toxicities were esophagitis (63.6%) and neutropenia (25%). Grade 3–4 postoperative morbidities included surgical wound infection (2.3%), acute renal failure (2.3%), and anastomosis stricture (2.3%).

Conclusion

Trimodality treatment with a high preoperative radiation dose and chemotherapy yielded a good pathologic complete response rate, and long‐term survival with low toxicities.

Synchronous bilateral breast cancer irradiation: clinical and dosimetrical issues using volumetric modulated arc therapy and simultaneous integrated boost

OBJECTIVES

The aim of the present retrospective analysis was to evaluate dosimetric parameters, feasibility and outcome for Synchronous Bilateral Breast Cancer (SBBC) patients treated with adjuvant radiotherapy (RT) by Volumetric Modulated Arc Therapy (VMAT).

METHODS

From September 2011 to April 2016, 1100 Breast Cancer (BC) patients were referred to our institution to receive adjuvant breast RT, and those with SBBC were selected for the present analysis. A total of 16 patients were identified. A total dose of 50 Gy in 25 fractions was prescribed to the Planning Target Volume of the whole bilateral breast (PTV_BN) with or without the supraclavicular and infraclavicular nodes, while a total dose of 60 Gy in 25 fractions was prescribed to the surgical bed (PTV_boost). Several V _xGy and Dx% parameters were analyzed for the PTVs, together with Conformity and Homogeneity indexes (CI, HI), and for the critical Organs at risk (OARs), lungs and heart first.

RESULTS

With a median follow-up of 24 months, no acute or late side effects more than grade 2 were observed. All patients are alive without any sign of disease. For target dose coverage, our observed inter-patients averages (±1 sd) were V _{95% Dp} = 96.7 ± 1.6% (96.3 ± 1.8%) to the left (right) PTV_BN, V _{95% Dp} = 98.6 ± 2.7% (99.4 ± 0.9%) to the left (right) PTV_boost, and D _2% = 64.4 ± 1.8 Gy (65.0 ± 2.0 Gy) to the left (right) PTV_boost, respectively. With regard to the heart, the inter-patient average of D _mean was 8.3 ± 3.3 Gy. For the lungs, the inter-patient average of D _mean, V _5 Gy and V _20 Gy were 11.8 ± 2.3 Gy, 78.9 ± 15.3% and 15.7 ± 5%, respectively.

CONCLUSIONS

The present retrospective analysis showed the feasibility, tolerability and safety of VMAT in the treatment of SBBC patients. Further studies are necessary to confirm these preliminary data.

Radiation Therapy for Locally Advanced Esophageal Cancer

The treatment of locally advanced esophageal cancer is controversial. For patients who are candidates for surgical resection, multiple prospective clinical trials have demonstrated the advantages of neoadjuvant chemoradiation. For patients who are medically inoperable, definitive chemoradiation is an alternative approach with survival rates comparable to trimodality therapy. Although trials of dose escalation are ongoing, the standard radiation dose remains 50.4 Gy. Modern radiotherapy techniques such as image-guided radiation therapy with motion management and intensity-modulated radiation therapy are strongly encouraged with a planning objective to maximize conformity to the intended target volume while reducing dose delivered to uninvolved normal tissues.

Bladder radiotherapy treatment: A retrospective comparison of 3-dimensional conformal radiotherapy, intensity-modulated radiation therapy, and volumetric-modulated arc therapy plans

To examine tumor׳s and organ׳s response when different radiotherapy plan techniques are used. Ten patients with confirmed bladder tumors were first treated using 3-dimensional conformal radiotherapy (3DCRT) and subsequently the original plans were re-optimized using the intensity-modulated radiation treatment (IMRT) and volumetric-modulated arc therapy (VMAT)-techniques. Targets coverage in terms of conformity and homogeneity index, TCP, and organs׳ dose limits, including integral dose analysis were evaluated. In addition, MUs and treatment delivery times were compared. Better minimum target coverage (1.3%) was observed in VMAT plans when compared to 3DCRT and IMRT ones confirmed by a statistically significant conformity index (CI) results. Large differences were observed among techniques in integral dose results of the femoral heads. Even if no statistically significant differences were reported in rectum and tissue, a large amount of energy deposition was observed in 3DCRT plans. In any case, VMAT plans provided better organs and tissue sparing confirmed also by the normal tissue complication probability (NTCP) analysis as well as a better tumor control probability (TCP) result. Our analysis showed better overall results in planning using VMAT techniques. Furthermore, a total time reduction in treatment observed among techniques including gantry and collimator rotation could encourage using the more recent one, reducing target movements and patient discomfort.

Bayesian regression analyses of radiation modality effects on pericardial and pleural effusion and survival in esophageal cancer

BACKGROUND AND PURPOSE

To evaluate radiation modality effects on pericardial effusion (PCE), pleural effusion (PE) and survival in esophageal cancer (EC) patients.

MATERIALS AND METHODS

We analyzed data from 470 EC patients treated with definitive concurrent chemoradiotherapy (CRT). Bayesian semi-competing risks (SCR) regression models were fit to assess effects of radiation modality and prognostic covariates on the risks of PCE and PE, and death either with or without these preceding events. Bayesian piecewise exponential regression models were fit for overall survival, the time to PCE or death, and the time to PE or death. All models included propensity score as a covariate to correct for potential selection bias.

RESULTS

Median times to onset of PCE and PE after RT were 7.1 and 6.1months for IMRT, and 6.5 and 5.4months for 3DCRT, respectively. Compared to 3DCRT, the IMRT group had significantly lower risks of PE, PCE, and death. The respective probabilities of a patient being alive without either PCE or PE at 3-years and 5-years were 0.29 and 0.21 for IMRT compared to 0.13 and 0.08 for 3DCRT. In the SCR regression analyses, IMRT was associated with significantly lower risks of PCE (HR=0.26) and PE (HR=0.49), and greater overall survival (probability of beneficial effect (pbe)>0.99), after controlling for known clinical prognostic factors.

CONCLUSIONS

IMRT reduces the incidence and postpones the onset of PCE and PE, and increases survival probability, compared to 3DCRT.

Inverse 4D conformal planning for lung SBRT using particle swarm optimization

A critical aspect of highly potent regimens such as lung stereotactic body radiation therapy (SBRT) is to avoid collateral toxicity while achieving planning target volume (PTV) coverage. In this work, we describe four dimensional conformal radiotherapy using a highly parallelizable swarm intelligence-based stochastic optimization technique. Conventional lung CRT-SBRT uses a 4DCT to create an internal target volume and then, using forward-planning, generates a 3D conformal plan. In contrast, we investigate an inverse-planning strategy that uses 4DCT data to create a 4D conformal plan, which is optimized across the three spatial dimensions (3D) as well as time, as represented by the respiratory phase. The key idea is to use respiratory motion as an additional degree of freedom. We iteratively adjust fluence weights for all beam apertures across all respiratory phases considering OAR sparing, PTV coverage and delivery efficiency. To demonstrate proof-of-concept, five non-small-cell lung cancer SBRT patients were retrospectively studied. The 4D optimized plans achieved PTV coverage comparable to the corresponding clinically delivered plans while showing significantly superior OAR sparing ranging from 26% to 83% for D max heart, 10%-41% for D max esophagus, 31%-68% for D max spinal cord and 7%-32% for V 13 lung.

A dose-volume histogram based decision-support system for dosimetric comparison of radiotherapy treatment plans

Background

The choice of any radiotherapy treatment plan is usually made after the evaluation of a few preliminary isodose distributions obtained from different beam configurations. Despite considerable advances in planning techniques, such final decision remains a challenging task that would greatly benefit from efficient and reliable assessment tools.

Methods

For any dosimetric plan considered, data on dose-volume histograms supplied by treatment planning systems are used to provide estimates on planning target coverage as well as on sparing of organs at risk and the remaining healthy tissue. These partial metrics are then combined into a dose distribution index (DDI), which provides a unified, easy-to-read score for each competing radiotherapy plan. To assess the performance of the proposed scoring system, DDI figures for fifty brain cancer patients were retrospectively evaluated. Patients were divided in three groups depending on tumor location and malignancy. For each patient, three tentative plans were designed and recorded during planning, one of which was eventually selected for treatment. We thus were able to compare the plans with better DDI scores and those actually delivered.

Results

When planning target coverage and organs at risk sparing are considered as equally important, the tentative plan with the highest DDI score is shown to coincide with that actually delivered in 32 of the 50 patients considered. In 15 (respectively 3) of the remaining 18 cases, the plan with highest DDI value still coincides with that actually selected, provided that organs at risk sparing is given higher priority (respectively, lower priority) than target coverage.

Conclusions

DDI provides a straightforward and non-subjective tool for dosimetric comparison of tentative radiotherapy plans. In particular, DDI readily quantifies differences among competing plans with similar-looking dose-volume histograms and can be easily implemented for any tumor type and localization, irrespective of the planning system and irradiation technique considered. Moreover, DDI permits to estimate the dosimetry impact of different priorities being assigned to sparing of organs at risk or to better target coverage.

Re-evaluating the optimal radiation dose for definitive chemoradiotherapy for esophageal squamous cell carcinoma

BACKGROUND

The optimal radiation dose for treating esophageal squamous cell carcinoma (ESCC) has long been debated. We evaluated if doses greater than 50.4 Gy delivered with modern techniques are beneficial in terms of tumor control, survival, and toxicity.

METHODS

We included 193 consecutive patients with ESCC treated with definitive concurrent chemoradiotherapy from 1998 to 2012. Patients were treated to a dose of ≤50.4 Gy (low-dose, n = 137) or greater than 50.4 Gy (high-dose, n = 56). Tumor response, local-regional control, survival, and treatment toxicity were compared between groups.

RESULTS

High-dose group had a significantly lower local failure rate (17.9% versus 34.3%, p = 0.024) and a marginal better 5-year local-regional failure-free survival (68.7% versus 55.9%, p = 0.052) than the low-dose group. No significant differences were found between high- and low-dose groups in tumor complete response rate (p = 0.975), regional failure rate (p = 0.336), distant metastasis rate (p = 0.390), or 5-year overall survival (p = 0.617). No difference in the incidence of toxic effects was observed between the two groups except for grade 3 skin reaction (12.5% [high] versus 2.2% [low], p < 0.001) and grade greater than or equal to 3 esophageal stricture (32.1% [high] versus 18.2% [low], p = 0.037).

CONCLUSIONS

Local tumor control might be improved by higher dose of greater than 50.4 Gy, when delivered with modern techniques and concurrent chemotherapy, at the consequence of increased toxicity without impact on overall survival.

High FDG uptake areas on pre-radiotherapy PET/CT identify preferential sites of local relapse after chemoradiotherapy for locally advanced oesophageal cancer

PURPOSE

The high failure rates in the radiotherapy (RT) target volume suggest that patients with locally advanced oesophageal cancer (LAOC) would benefit from increased total RT doses. High 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) uptake (hotspot) on pre-RT FDG positron emission tomography (PET)/CT has been reported to identify intra-tumour sites at increased risk of relapse after RT in non-small cell lung cancer and in rectal cancer. Our aim was to confirm these observations in patients with LAOC and to determine the optimal maximum standardized uptake value (SUVmax) threshold to delineate smaller RT target volumes that would facilitate RT dose escalation without impaired tolerance.

METHODS

The study included 98 consecutive patients with LAOC treated by chemoradiotherapy (CRT). All patients underwent FDG PET/CT at initial staging and during systematic follow-up in a single institution. FDG PET/CT acquisitions were coregistered on the initial CT scan. Various subvolumes within the initial tumour (30, 40, 50, 60, 70, 80 and 90% SUVmax thresholds) and in the subsequent local recurrence (LR, 40 and 90% SUVmax thresholds) were pasted on the initial CT scan and compared[Dice, Jaccard, overlap fraction (OF), common volume/baseline volume, common volume/recurrent volume].

RESULTS

Thirty-five patients had LR. The initial metabolic tumour volume was significantly higher in LR tumours than in the locally controlled tumours (mean 25.4 vs 14.2 cc; p = 0.002). The subvolumes delineated on initial PET/CT with a 30-60% SUVmax threshold were in good agreement with the recurrent volume at 40% SUVmax (OF = 0.60-0.80). The subvolumes delineated on initial PET/CT with a 30-60% SUVmax threshold were in good to excellent agreement with the core volume (90% SUVmax) of the relapse (common volume/recurrent volume and OF indices 0.61-0.89).

CONCLUSION

High FDG uptake on pretreatment PET/CT identifies tumour subvolumes that are at greater risk of recurrence after CRT in patients with LAOC. We propose a 60% SUVmax threshold to delineate high FDG uptake areas on initial PET/CT as reduced target volumes for RT dose escalation.

Predictive factors for acute radiation pneumonitis in postoperative intensity modulated radiation therapy and volumetric modulated arc therapy of esophageal cancer

Background

Radiation pneumonitis (RP) is a common side reaction in radiotherapy for esophageal cancer. There are few reports about RP in esophageal cancer patients receiving postoperative intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). This study aims to analyze clinical or dosimetric factors associated with RP, and provides data for radiotherapy planning.

Methods

We reviewed 68 postoperative esophageal cancer patients who were treated with radiotherapy at the West China Hospital from October 2010 to November 2012 to identify any correlation between the clinical or dosimetric parameters and acute radiation pneumonitis (ARP) or severe acute radiation pneumonitis (SARP) by t-test, chi-square test, and logistic regression analysis.

Results

Of the 68 patients, 33 patients (48.5%) developed ARP, 13 of which (19.1%) developed SARP. Of these 33 patients, 8 (11.8%), 12 (17.6%), 11 (16.2%), and 2 (2.9%) patients were grade 1, 2, 3, and 4 ARP, respectively. Univariate analysis showed that lung infection during radiotherapy, use of VMAT, mean lung dose (MLD), and dosimetric parameters (e.g. V20, V30) are significantly correlated with RP. Multivariate analysis found that lung infection during radiotherapy, MLD ≥ 12 Gy, and V30 ≥ 13% are significantly correlated with an increased risk of RP.

Conclusion

Lung infection during radiotherapy and low radiation dose volume distribution were predictive factors associated with RP and should be accounted for during radiation planning.

Intensity modulated radiotherapy (IMRT) with concurrent chemotherapy as definitive treatment of locally advanced esophageal cancer

Background

To report our experience with increased dose intensity-modulated radiation and concurrent systemic chemotherapy as definitive treatment of locally advanced esophageal cancer.

Patients and methods

We analyzed 27 consecutive patients with histologically proven esophageal cancer, who were treated with increased-dose IMRT as part of their definitive therapy. The majority of patients had T3/4 and/or N1 disease (93%). Squamous cell carcinoma was the dominating histology (81%). IMRT was delivered in step-and-shoot technique in all patients using an integrated boost concept. The boost volume was covered with total doses of 56-60 Gy (single dose 2-2.14 Gy), while regional nodal regions received 50.4 Gy (single dose 1.8 Gy) in 28 fractions. Concurrent systemic therapy was scheduled in all patients and administered in 26 (96%). 17 patients received additional adjuvant systemic therapy. Loco-regional control, progression-free and overall survival as well as acute and late toxicities were retrospectively analyzed. In addition, quality of life was prospectively assessed according to the EORTC QLQs (QLQ-OG25, QLQ-H&N35 and QLQ-C30).

Results

Radiotherapy was completed as planned in all but one patient (96%), and 21 patients received more than 80% of the planned concurrent systemic therapy. We observed ten locoregional failures, transferring into actuarial 1-, 2- and 3-year-locoregional control rates of 77%, 65% and 48%. Seven patients developed distant metastases, mainly to the lung (71%). The actuarial 1-, 2- and 3-year-disease free survival rates were 58%, 48% and 36%, and overall survival rates were 82%, 61% and 56%. The concept was well tolerated, both in the clinical objective examination and also according to the subjective answers to the QLQ questionnaire. 14 patients (52%) suffered from at least one acute CTC grade 3/4 toxicity, mostly hematological side effects or dysphagia. Severe late toxicities were reported in 6 patients (22%), mostly esophageal strictures and ulcerations. Severe side effects to skin, lung and heart were rare.

Conclusion

IMRT with concurrent systemic therapy in the definitive treatment of esophageal cancer using an integrated boost concept with doses up to 60 Gy is feasible and yields good results with acceptable acute and late overall toxicity and low side effects to skin, lung and heart.

Concurrent three-dimensional conformal radiotherapy and chemotherapy for postoperative recurrence of mediastinal lymph node metastases in patients with esophageal squamous cell carcinoma: a phase 2 single-institution study

AIM

The aim of this study was to evaluate the effects of radiotherapy plus concurrent weekly cisplatin chemotherapy on the postoperative recurrence of mediastinal lymph node metastases in esophageal cancer patients.

METHODS

Ninety-eight patients were randomly enrolled to receive either three-dimensional conformal radiotherapy alone (group A) or concurrent chemoradiotherapy (group B). A radiation dose of 62-70 Gy/31-35 fractions was delivered to the recurrent tumor. Furthermore, the patients in group B simultaneously received weekly doses of cisplatin (30 mg/m(2)), and the survival outcomes and toxic effects were compared.

RESULTS

The response rate of group B (91.8%) was significantly greater than that of group A (73.5%) (χ(2) = 5.765, P = 0.016). The 1- and 3-year survival rates of group B (85.7% and 46.9%, respectively) were also greater than those of group A (69.4% and 28.6%, respectively). However, there were no significant differences in the 5-year survival rates. The numbers of patients who died of distant metastases in groups A and B were 13 (26.5%) and 5 (10.2%), respectively (χ(2) = 4.356, P = 0.036). Acute radiation-related esophagitis and granulocytopenia in group B was frequent. However, intergroup differences in terms of late toxicity were not significant.

CONCLUSIONS

Three-dimensional conformal radiotherapy (3DCRT) is a practical and feasible technique to treat the recurrence of mediastinal lymph node metastases of postoperative esophageal cancer. In addition, concurrent chemotherapy can increase local tumor control, decrease the distant metastasis rate, and increase the long-term survival rate.

Detection of interfraction displacement and volume variance during radiotherapy of primary thoracic esophageal cancer based on repeated four-dimensional CT scans

Background

To investigate the interfraction displacement and volume variation of primary thoracic esophagus carcinoma with enhanced four-dimensional computed tomography (4DCT) scanning during fractionated radiotherapy.

Methods

4DCT data sets were acquired at the time of treatment simulation and every ten fraction for each of 32 patients throughout treatment. Scans were registered to baseline (simulation) 4DCT scans by using bony landmarks. The gross tumor volumes (GTVs) were delineated on each data set. Coordinates of the GTV centroids were acquired on each respiration phase. Distance between center of the GTV contour on the simulation scan and the centers on subsequent scans were used to assess interfraction displacement between fractions. Volumes were constructed using three approaches: The GTV delineated from the maximum intensity projection (MIP) was defined IGTV_MIP, all 10 GTVs were combined to form IGTV₁₀, GTV_mean was the average of all 10 phases of each GTV.

Results

Interfraction displacement in left-right (LR), anterior-posterior (AP), superior-inferior (SI) directions and 3D vector were 0.13 ± 0.09 cm, 0.16 ± 0.12 cm, 0.34 ± 0.26 cm and 0.43 ± 0.24 cm, respectively between the tenth fraction and simulation 4DCT scan. 0.14 ± 0.09 cm, 0.19 ± 0.16 cm, 0.45 ± 0.43 cm and 0.56 ± 0.40 cm in LR, AP, SI and 3D vector respectively between the twentieth fraction and simulation 4DCT scan. Displacement in SI direction was larger than LR and AP directions during treatment. For distal esophageal cancer, increased interfraction displacements were observed in SI direction and 3D vector (P = 0.002 and P = 0.001, respectively) during radiotherapy. The volume of GTV_mean, IGTV_MIP, and IGTV₁₀ decreased significantly at the twentieth fraction for middle (median: 34.01%, 33.09% and 28.71%, respectively) and distal (median: 22.76%, 25.27% and 23.96%, respectively) esophageal cancer, but for the upper third, no significant variation were observed during radiotherapy.

Conclusions

Interfractional displacements in SI direction were larger than LR and AP directions. For distal location, significant changes were observed in SI direction and 3D vector during radiotherapy. For middle and distal locations, the best time to reset position should be selected at the twentieth fraction when the primary tumor target volume changed significantly, and it was preferable to guide target correction and planning modification.

Long-term outcomes and prognostic factors for patients with esophageal cancer following radiotherapy

AIM: To evaluate long-term outcomes and prognostic factors for esophageal squamous cell carcinoma (SCC) treated with three dimensional conformal radiotherapy (3D-CRT).

METHODS: Between January 2005 and December 2006, 153 patients (120 males, 33 females) with pathologically confirmed esophageal SCC and treated with 3D-CRT in Cancer Hospital of Shantou University were included in this retrospective analysis. Median age was 60 years (range: 37-84 years). The proportion of tumor location was as follows: upper thorax (including the cervical region), 73 (48%); middle thorax, 73 (48%); lower thorax, 7 (5%), respectively. The median radiation dose was 64 Gy (range: 50-74 Gy). Fifty four cases (35%) received cisplatin-based concurrent chemotherapy. Univariate and multivariate analysis were performed to determine the association between the correlative factors and prognosis.

RESULTS: The five-year overall survival rate was 26.3%, with a median follow-up of 49 mo (range: 3-66 mo) for patients who were still alive. On univariate analysis, lesion location, lesion length by barium esophagogram, computed tomography imaging characteristics including Y diameter (anterior-posterior, AP, extent of tumor), gross tumor volume of primary lesion (GTV-E), volume of positive lymph nodes (GTV-LN), and the total target volume (GTV-T = GTV-E + GTV-LN) were prognostic for overall survival. By multivariate analysis, only the Y diameter [hazard ratio (HR) 2.219, 95%CI 1.141-4.316, P = 0.019] and the GTV-T (HR 1.372, 95%CI 1.044-1.803, P = 0.023) were independent prognostic factors for survival.

CONCLUSION: The overall survival of esophageal carcinoma patients undergoing 3D-CRT was promising. The best predictors for survival were GTV-T and Y diameter.

Propensity score-based comparison of long-term outcomes with 3-dimensional conformal radiotherapy vs intensity-modulated radiotherapy for esophageal cancer

PURPOSE

Although 3-dimensional conformal radiotherapy (3D-CRT) is the worldwide standard for the treatment of esophageal cancer, intensity modulated radiotherapy (IMRT) improves dose conformality and reduces the radiation exposure to normal tissues. We hypothesized that the dosimetric advantages of IMRT should translate to substantive benefits in clinical outcomes compared with 3D-CRT.

METHODS AND MATERIALS

An analysis was performed of 676 nonrandomized patients (3D-CRT, n=413; IMRT, n=263) with stage Ib-IVa (American Joint Committee on Cancer 2002) esophageal cancers treated with chemoradiotherapy at a single institution from 1998-2008. An inverse probability of treatment weighting and inclusion of propensity score (treatment probability) as a covariate were used to compare overall survival time, interval to local failure, and interval to distant metastasis, while accounting for the effects of other clinically relevant covariates. The propensity scores were estimated using logistic regression analysis.

RESULTS

A fitted multivariate inverse probability weighted-adjusted Cox model showed that the overall survival time was significantly associated with several well-known prognostic factors, along with the treatment modality (IMRT vs 3D-CRT, hazard ratio 0.72, P<.001). Compared with IMRT, 3D-CRT patients had a significantly greater risk of dying (72.6% vs 52.9%, inverse probability of treatment weighting, log-rank test, P<.0001) and of locoregional recurrence (P=.0038). No difference was seen in cancer-specific mortality (Gray's test, P=.86) or distant metastasis (P=.99) between the 2 groups. An increased cumulative incidence of cardiac death was seen in the 3D-CRT group (P=.049), but most deaths were undocumented (5-year estimate, 11.7% in 3D-CRT vs 5.4% in IMRT group, Gray's test, P=.0029).

CONCLUSIONS

Overall survival, locoregional control, and noncancer-related death were significantly better after IMRT than after 3D-CRT. Although these results need confirmation, IMRT should be considered for the treatment of esophageal cancer.

3D-conformal RT, fixed-field IMRT and RapidArc, which one is better for esophageal carcinoma treated with elective nodal irradiation

The purpose of this study is to compare the characteristics of 3D-conformal radiotherapy (3D-CRT), fixed-field intensity-modulated radiotherapy (IMRT) and RapidArc for esophageal squamous cell carcinoma (ESCC) treated with elective nodal irradiation (ENI). CT datasets of 20 patients with ESCC were included and plans for single and double arcs of RapidArc (RA1 and RA2), 7-field IMRT and 3D-CRT were created and optimized for each patient. The goal was to deliver 59.6 Gy to ≥95% of the planning target volume (40 Gy to electively irradiated lymph nodal regions) while meeting the same normal-tissue dose constraints. The plans were compared based on dosimetric characteristics of target and organs at risk (OARs), monitor units (MUs), and appraised beam-on time. Both RA2 and IMRT resulted in similar target coverage (V95%, 97.84±1.50% for RA2 versus 96.96±1.15% for IMRT), homogeneity index (HI, 0.11±0.02 for RA2 versus 0.10±0.01 for IMRT) and conformity index (CI, 0.81±0.03 for RA2 versus 0.79±0.04 for IMRT), which displayed slightly better than single arc (V95%=94.55±1.50%, HI=0.12±0.02, CI=0.80±0.02) and much better than 3D-CRT (V95%=91.17±2.89%, HI=0.15±0.03, CI=0.60±0.07). The total lung V20, V30 was reduced approximately from 31%, 16% (3D-CRT) to 22%, 13% (IMRT) and 20%, 12% (RA2); the heart V30, V40 from 29%, 21% (3D-CRT) to 28%, 20% (IMRT) and 27%, 18% (RA2). The maximum dose to the spinal cord was 44.26±2.60 Gy for 3D-CRT, 42.47±2.40 Gy for IMRT, and 42.79±1.81 Gy for RA2. The number of MUs per fraction reduced from 990±165 (IMRT) to 503±70 (3D-CRT) and 502±79 (RA2). Appraised beam-on time of RapidArc was 1.2-2.4 min, which was lower than IMRT with 5.4 min by average. RapidArc, especially for double arcs plan could provide slight improvements in OARs sparing and lower MUs without compromised target qualities compared with IMRT, which was much better than 3D-CRT for ESCC treated with ENI.

Comparative study of convolution, superposition, and fast superposition algorithms in conventional radiotherapy, three-dimensional conformal radiotherapy, and intensity modulated radiotherapy techniques for various sites, done on CMS XIO planning system

The aim of this study is to compare the dosimetry results that are obtained by using Convolution, Superposition and Fast Superposition algorithms in Conventional Radiotherapy, Three-Dimensional Conformal Radiotherapy (3D-CRT), and Intensity Modulated Radiotherapy (IMRT) for different sites, and to study the suitability of algorithms with respect to site and technique. For each of the Conventional, 3D-CRT, and IMRT techniques, four different sites, namely, Lung, Esophagus, Prostate, and Hypopharynx were analyzed. Treatment plans were created using 6MV Photon beam quality using the CMS XiO (Computerized Medical System, St.Louis, MO) treatment planning system. The maximum percentage of variation recorded between algorithms was 3.7% in case of Ca.Lung, for the IMRT Technique. Statistical analysis was performed by comparing the mean relative difference, Conformity Index, and Homogeneity Index for target structures. The fast superposition algorithm showed excellent results for lung and esophagus cases for all techniques. For the prostate, the superposition algorithm showed better results in all techniques. In the conventional case of the hypopharynx, the convolution algorithm was good. In case of Ca. Lung, Ca Prostate, Ca Esophagus, and Ca Hypopharynx, OARs got more doses with the superposition algorithm; this progressively decreased for fast superposition and convolution algorithms, respectively. According to this study the dosimetric results using different algorithms led to significant variation and therefore care had to be taken while evaluating treatment plans. The choice of a dose calculation algorithm may in certain cases even influence clinical results.

Technological advances in radiotherapy for esophageal cancer

Radiotherapy with concurrent chemotherapy and surgery represent the main treatment modalities in esophageal cancer. The goal of modern radiotherapy approaches, based on recent technological advances, is to minimize post-treatment complications by improving the gross tumor volume definition (positron emission tomography-based planning), reducing interfraction motion (image-guided radiotherapy) and intrafraction motion (respiratory-gated radiotherapy), and by better dose delivery to the precisely defined planning target volume (intensity-modulated radiotherapy and proton therapy). Reduction of radiotherapy-related toxicity is fundamental to the improvement of clinical results in esophageal cancer, although the dose escalation concept is controversial.

Dose-volume histogram parameters and clinical factors associated with pleural effusion after chemoradiotherapy in esophageal cancer patients

PURPOSE

To investigate the dose-volume histogram parameters and clinical factors as predictors of pleural effusion in esophageal cancer patients treated with concurrent chemoradiotherapy (CRT).

METHODS AND MATERIALS

Forty-three esophageal cancer patients treated with definitive CRT from January 2001 to March 2007 were reviewed retrospectively on the basis of the following criteria: pathologically confirmed esophageal cancer, available computed tomography scan for treatment planning, 6-month follow-up after CRT, and radiation dose ≥ 50 Gy. Exclusion criteria were lung metastasis, malignant pleural effusion, and surgery. Mean heart dose, mean total lung dose, and percentages of heart or total lung volume receiving ≥ 10-60 Gy (Heart-V(10) to V(60) and Lung-V(10) to V(60), respectively) were analyzed in relation to pleural effusion.

RESULTS

The median follow-up time was 26.9 months (range, 6.7-70.2) after CRT. Of the 43 patients, 15 (35%) developed pleural effusion. By univariate analysis, mean heart dose, Heart-V(10) to V(60), and Lung-V(50) to V(60) were significantly associated with pleural effusion. Poor performance status, primary tumor of the distal esophagus, and age ≥ 65 years were significantly related with pleural effusion. Multivariate analysis identified Heart-V(50) as the strongest predictive factor for pleural effusion (p = 0.01). Patients with Heart-V(50) <20%, 20%≤ Heart-V(50) <40%, and Heart-V(50) ≥ 40% had 6%, 44%, and 64% of pleural effusion, respectively (p < 0.01).

CONCLUSION

Heart-V(50) is a useful parameter for assessing the risk of pleural effusion and should be reduced to avoid pleural effusion.

The potential of proton beam radiation therapy in gastrointestinal cancer

A group of Swedish oncologists and hospital physicists have estimated the number of patients in Sweden suitable for proton beam therapy. The estimations have been based on current statistics of tumour incidence, number of patients potentially eligible for radiation treatment, scientific support from clinical trials and model dose planning studies and knowledge of the dose-response relations of different tumours and normal tissues. In gastrointestinal cancers, it is assessed that at least 345 patients, mainly non-resectable rectal cancers, oesophageal and liver cancers, are eligible. Great uncertainties do however exist both in the number of patients with gastrointestinal cancers suitable for radiation therapy, and in the proportion of those where proton beams may give sufficiently better results.

Temporal change in brain natriuretic Peptide after radiotherapy for thoracic esophageal cancer

PURPOSE

To investigate the relationships of plasma levels of brain natriuretic peptide (BNP) with abnormal (18)F-fluorodeoxyglucose (FDG) accumulation in the myocardium corresponding to irradiated fields and temporal changes in BNP, which is used as an index of heart remodeling, after radiotherapy for the mediastinum.

MATERIALS AND METHODS

Brain natriuretic peptide concentrations were measured before and after radiotherapy for thoracic esophageal cancer, and the change in BNP concentration after radiotherapy was investigated. Moreover, FDG accumulation in the myocardium was investigated in patients who had undergone FDG positron emission tomography less than 14 days before or after measurement of BNP concentration, and the Mann-Whitney U test was used to detect significant difference between BNP concentrations in patients with and without abnormal FDG accumulation corresponding to the irradiated field.

RESULTS

There was significant difference between the levels of BNP in patients without abnormal FDG accumulation in the irradiated myocardium and in patients with abnormal FDG accumulation (p < 0.001). The levels of BNP in the 9-24 months after radiotherapy group and in the >24 months after radiotherapy group were significantly higher than the levels in the before radiotherapy group, immediately after radiotherapy group, 1-2 months after radiotherapy group, and control group.

CONCLUSIONS

The level of BNP was significantly increased more than 9 months after the start of radiotherapy and was significantly higher in patients who had high FDG accumulation corresponding to the irradiated field. The results of this study indicate that BNP concentration might be an early indicator of radiation-induced myocardial damage.

Intensity-modulated radiation therapy with concurrent chemotherapy for locally advanced cervical and upper thoracic esophageal cancer

AIM: To evaluate the dosimetry, efficacy and toxicity of intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy for patients with locally advanced cervical and upper thoracic esophageal cancer.

METHODS: A retrospective study was performed on 7 patients who were definitively treated with IMRT and concurrent chemotherapy. Patients who did not receive IMRT radiation and concurrent chemotherapy were not included in this analysis. IMRT plans were evaluated to assess the tumor coverage and normal tissue avoidance. Treatment response was evaluated and toxicities were assessed.

RESULTS: Five- to nine-beam IMRT were used to deliver a total dose of 59.4-66 Gy (median: 64.8 Gy) to the primary tumor with 6-MV photons. The minimum dose received by the planning tumor volume (PTV) of the gross tumor volume boost was 91.2%-98.2% of the prescription dose (standard deviation [SD]: 3.7%-5.7%). The minimum dose received by the PTV of the clinical tumor volume was 93.8%-104.8% (SD: 4.3%-11.1%) of the prescribed dose. With a median follow-up of 15 mo (range: 3-21 mo), all 6 evaluable patients achieved complete response. Of them, 2 developed local recurrences and 2 had distant metastases, 3 survived with no evidence of disease. After treatment, 2 patients developed esophageal stricture requiring frequent dilation and 1 patient developed tracheal-esophageal fistula.

CONCLUSION: Concurrent IMRT and chemotherapy resulted in an excellent early response in patients with locally advanced cervical and upper thoracic esophageal cancer. However, local and distant recurrence and toxicity remain to be a problem. Innovative approaches are needed to improve the outcome.

Comparison of forward planning with automated inverse planning for three-dimensional conformal radiotherapy of non-small cell lung cancer without IMRT

The forward and inverse treatment plans of 10 patients with lung cancer were compared in terms of PTV coverage, sparing of normal lung and time required to generate a plan. The inverse planning produced as good treatment plans as an experienced dosimetrist with considerable reduction in staff time. When translated to other complex sites, inverse non-IMRT planning may have considerable impact on manpower requirements.

Feasibility of using intensity-modulated radiotherapy to improve lung sparing in treatment planning for distal esophageal cancer

BACKGROUND AND PURPOSE

To evaluate the feasibility whether intensity-modulated radiotherapy (IMRT) can be used to reduce doses to normal lung than three-dimensional conformal radiotherapy (3 DCRT) in treating distal esophageal malignancies.

PATIENTS AND METHODS

Ten patient cases with cancer of the distal esophagus were selected for a retrospective treatment-planning study. IMRT plans using four, seven, and nine beams (4B, 7B, and 9B) were developed for each patient and compared with the 3 DCRT plan used clinically. IMRT and 3 DCRT plans were evaluated with respect to PTV coverage and dose-volumes to irradiated normal structures, with statistical comparison made between the two types of plans using the Wilcoxon matched-pair signed-rank test.

RESULTS

IMRT plans (4B, 7B, 9B) reduced total lung volume treated above 10 Gy (V(10)), 20 Gy (V(20)), mean lung dose (MLD), biological effective volume (V(eff)), and lung integral dose (P<0.05). The median absolute improvement with IMRT over 3DCRT was approximately 10% for V(10), 5% for V(20), and 2.5 Gy for MLD. IMRT improved the PTV heterogeneity (P<0.05), yet conformity was better with 7B-9B IMRT plans. No clinically meaningful differences were observed with respect to the irradiated volumes of spinal cord, heart, liver, or total body integral doses.

CONCLUSIONS

Dose-volume of exposed normal lung can be reduced with IMRT, though clinical investigations are warranted to assess IMRT treatment outcome of esophagus cancers.