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

Cost-utility analysis of proton beam therapy for locally advanced esophageal cancer in Japan

PURPOSE

Proton beam therapy (PBT) has recently been included in Japan's health insurance benefit package for certain cancer types. This study aimed to determine the cost-effectiveness of PBT as a replacement for conventional three-dimensional conformal radiotherapy (3D-CRT) for locally advanced esophageal cancer (LAEC) that is not covered by social insurance.

METHODS

We estimated the incremental cost-effectiveness ratio (ICER) of PBT as a replacement for 3D-CRT, using clinical evidence from the literature and expert opinions. We used an economic model, decision tree, and Markov model to illustrate the courses followed by patients with LAEC. Effectiveness was estimated as quality-adjusted life years (QALY) using utility weights for the health state. Social insurance fees were calculated as costs. We assumed two base cases depending on the two existing levels of fees for PBT in social insurance: 2,735,000 Japanese yen (US$20,652) or 1,600,000 yen (US$13,913). The stability of the ICER against these assumptions was appraised using sensitivity analysis.

RESULTS

The effectiveness of PBT and 3D-CRT was 2.62 and 2.51 QALY, respectively. The estimated ICER was 14,025,268 yen (US$121,958) per QALY for the higher fee level and 7,026,402 yen (US$61,099) for the lower fee level. According to the Japanese threshold for cost-effectiveness of anticancer therapy of 7,500,000 yen (US$65,217) per QALY gain, the inclusion of PBT for LAEC in the benefit package of social insurance is cost-effective if a lower fee is applied.

CONCLUSION

PBT is a cost-effective alternative to 3D-CRT for LAEC and making it available to patients under social insurance could be justifiable.

Consequences of ionizing radiation exposure to the cardiovascular system

Ionizing radiation is widely used in various industrial and medical applications, resulting in increased exposure for certain populations. Lessons from radiation accidents and occupational exposure have highlighted the cardiovascular and cerebrovascular risks associated with radiation exposure. In addition, radiation therapy for cancer has been linked to numerous cardiovascular complications, depending on the distribution of the dose by volume in the heart and other relevant target tissues in the circulatory system. The manifestation of symptoms is influenced by numerous factors, and distinct cardiac complications have previously been observed in different groups of patients with cancer undergoing radiation therapy. However, in contemporary radiation therapy, advances in treatment planning with conformal radiation delivery have markedly reduced the mean heart dose and volume of exposure, and these variables are therefore no longer sole surrogates for predicting the risk of specific types of heart disease. Nevertheless, certain cardiac substructures remain vulnerable to radiation exposure, necessitating close monitoring. In this Review, we provide a comprehensive overview of the consequences of radiation exposure on the cardiovascular system, drawing insights from various cohorts exposed to uniform, whole-body radiation or to partial-body irradiation, and identify potential risk modifiers in the development of radiation-associated cardiovascular disease.

Bone versus soft-tissue setup in proton therapy for patients with oesophageal cancer

BACKGROUND

The aim of this study was to investigate the effect of patient positioning based on either bone or soft-tissue matching for PT in oesophageal cancer and its impact on plan adaptation.

MATERIALS AND METHODS

Two retrospective patient cohorts treated with radiotherapy were included in the study. Cohort A consisted of 26 consecutive patients with a planning 4DCT scan (CT1) and a surveillance 4DCT scan (CT2) at fraction ten. Cohort B consisted of 17 patients selected based on large anatomical changes identified during treatment resulting in a rescan (CT2). Mean dose to the iCTV (sum of the CTVs in all respiratory phases) was 50.4 Gy (RBE) in 28 fractions or 41.4 Gy (RBE) in 23 fractions. A nominal pencil beam scanning plan was created using two posterior beams and robust optimization (5 mm setup, 3.5% range). For each patient, two rigid registrations were made between average (avg) CT1 and CT2: a match on the vertebral column (bone match) and a match on the iCTV (soft-tissue match). Robustness towards setup (5 mm) and range (3.5%) errors was evaluated at CT2. Robustness towards respiration was evaluated by recalculation of the plan on all phases of the CT2 scan. Dose coverage <96% would trigger adaptation. The statistical significance (p-value <0.05) between dose coverage for the two registration methods was assessed using the Wilcoxon signed rank test.

RESULTS

All plans fulfilled V95%_iCTV>99% for the nominal plan and V95%_iCTV>97% for all respiratory phases and robustness scenarios at CT1. In two (8%) and three (18%) patients, V95%_iCTV<96% on CT2 for Cohort A and B, respectively when bone match was used. For soft-tissue match, V95%iCTV >96% for all patients. V95%_iCTV was significantly higher (p-value = 0.0001) for soft-tissue match than bone match.

CONCLUSION

Anatomical changes during the treatment course led to target dose deterioration and a need for plan adaptation when using a bone match.

A Critical Review of Radiation Therapy: From Particle Beam Therapy (Proton, Carbon, and BNCT) to Beyond

In this paper, we discuss the role of particle therapy—a novel radiation therapy (RT) that has shown rapid progress and widespread use in recent years—in multidisciplinary treatment. Three types of particle therapies are currently used for cancer treatment: proton beam therapy (PBT), carbon-ion beam therapy (CIBT), and boron neutron capture therapy (BNCT). PBT and CIBT have been reported to have excellent therapeutic results owing to the physical characteristics of their Bragg peaks. Variable drug therapies, such as chemotherapy, hormone therapy, and immunotherapy, are combined in various treatment strategies, and treatment effects have been improved. BNCT has a high dose concentration for cancer in terms of nuclear reactions with boron. BNCT is a next-generation RT that can achieve cancer cell-selective therapeutic effects, and its effectiveness strongly depends on the selective ¹⁰B accumulation in cancer cells by concomitant boron preparation. Therefore, drug delivery research, including nanoparticles, is highly desirable. In this review, we introduce both clinical and basic aspects of particle beam therapy from the perspective of multidisciplinary treatment, which is expected to expand further in the future.

Dosimetric Comparison Between Carbon-ion Radiotherapy and Photon Radiotherapy for Stage I Esophageal Cancer

BACKGROUND/AIM

The present study aimed to compare the radiation dose distribution of carbon-ion radiotherapy (CIRT) for stage I esophageal cancer with three-dimensional conformal radiotherapy (3DCRT) and volumetric modulated arc therapy (VMAT).

PATIENTS AND METHODS

Fifteen patients with cT1bN0M0 esophageal cancer who received 3DCRT at Kanagawa Cancer Center between January 2014 and April 2019 were enrolled. The dose-volume histogram parameters of the target volume and normal organs planned with CIRT, 3DCRT, and VMAT were evaluated.

RESULTS

The homogeneity index for the target volume of CIRT was significantly lower than that of 3DCRT and VMAT. In addition, the radiation dose of CIRT to the heart, lungs, spinal cord, and skin was significantly lower than that of 3DCRT and VMAT.

CONCLUSION

Favorable dose distributions with CIRT were demonstrated compared with 3DCRT and VMAT for esophageal cancer.

Long-term follow-up of a phase I/II trial of radiation dose escalation by simultaneous integrated boost for locally advanced esophageal squamous cell carcinoma

BACKGROUND

To observe the long-term survival and late adverse events in a phase Ⅰ/Ⅱ trial (NCT01843049) of dose escalation for thoracic esophageal squamous cell carcinoma (ESCC) with simultaneous integrated boost (SIB) technique.

METHODS

Patients with ESCC were treated with escalating radiation dose of four predefined levels. Dose of 62.5-64 Gy/25-32 fractions was delivered to the gross tumor volume (GTV), with (Level 3&4) or without (Level 1&2) a SIB up to 70 Gy for pre-treatment 50% SUVmax area of GTV. Patients also received 2 cycles of chemotherapy of cisplatin and fluorouracil concurrently and 2 more cycles after radiotherapy.

RESULTS

Median follow-up duration was 17.2 (2.5-83.4) months for all 44 patients and 47.2 (3.9-83.4) months for 25 survivors. The 3-year overall survival and progression-free survival rates were 57.6% and 41.0%, respectively. One, one, four and twelve severe (grade≥3) esophageal late adverse events (SEAE) occurred in patients of Level 1/2/3/4 (n = 5/10/16/13), with median occurrence time of 6.5 months. In univariable and multivariable competing risk models, maximal dose of the esophagus (Dmax) was found to have significant impact on the incidence of SEAE, and the cutoff distinguishing patients who developed SEAE or not was 77 Gy.

CONCLUSION

Boosting the gross tumor to 63 Gy while delivering 50.4 Gy to subclinical diseases in 28 fractions in locally advanced ESCC is well tolerated with promising long-term survival. Intenser dose regimen should be considered with caution before further toxicity assessment. Esophageal Dmax was significantly associated with severe late esophageal injury, while more findings of dose-volume predictors need larger-sample investigation.

Dosimetric and Radiobiological Comparison of External Beam Radiotherapy Using Simultaneous Integrated Boost Technique for Esophageal Cancer in Different Location

Objectives: To compare treatment plans of intensity modulated radiotherapy (IMRT), volumetric modulated arc radiotherapy (VMAT), and helical tomotherapy (HT) with simultaneous integrated boost (SIB) technique for esophageal cancer (EC) of different locations using dosimetry and radiobiology. Methods: Forty EC patients were planned for IMRT, VMAT, and HT plans, including 10 cases located in the cervix, upper, middle, and lower thorax, respectively. Dose-volume metrics, conformity index (CI), homogeneity index (HI), tumor control probability (TCP), and normal tissue complication probability (NTCP) were analyzed to evaluate treatment plans. Results: HT showed significant improvement over IMRT and VMAT in terms of CI (p = 0.007), HI (p < 0.001), and TCP (p < 0.001) in cervical EC. IMRT yielded more superior CI, HI and TCP compared with VMAT and HT in upper and middle thoracic EC (all p < 0.05). Additionally, V30 (27.72 ± 8.67%), mean dose (1801.47 ± 989.58cGy), and NTCP (Niemierko model: 0.44 ± 0.55%; Lyman-Kutcher-Burman model: 0.61 ± 0.59%) of heart in IMRT were sharply reduced than VMAT and HT in middle thoracic EC. For lower thoracic EC, the three techniques offered similar CI and HI (all p > 0.05). But VMAT dramatically lowered liver V30 (9.97 ± 2.84%), and reduced NTCP of lungs (Niemierko model: 0.47 ± 0.48%; Lyman-Kutcher-Burman model: 1.41 ± 1.07%) and liver (Niemierko model: 0.10 ± 0.08%; Lyman-Kutcher-Burman model: 0.17 ± 0.17%). Conclusions: HT was a good option for cervical EC with complex target coverage but little lungs and heart involvement as it achieved superior dose conformity and uniformity. Due to potentially improving tumor control and reducing heart dose with acceptable lungs sparing, IMRT was a preferred choice for upper and middle thoracic EC with large lungs involvement. VMAT could ameliorate therapeutic ratio and lower lungs and liver toxicity, which was beneficial for lower thoracic EC with little thoracic involvement but being closer to heart and liver. Individually choosing optimal technique for EC in different location will be warranted.

Local field radiotherapy without elective nodal irradiation for postoperative loco-regional recurrence of esophageal cancer

Background

Radiotherapy is an effective treatment for the postoperative loco-regional recurrence of esophageal cancer; however, the optimal treatment field remains controversial. This study aims to evaluate the outcome of local field radiotherapy without elective nodal irradiation for postoperative loco-regional recurrence of esophageal cancer.

Methods

We retrospectively investigated 35 patients treated for a postoperative loco-regional recurrence of esophageal cancer with local field radiotherapy between December 2008 and March 2016. The median irradiation dose was 60 Gy (range: 50-67.5 Gy). Thirty-one (88.6%) patients received concurrent chemotherapy.

Results

The median follow-up period was 18 months (range: 5-94 months). The 2-year overall survival was 55.7%, with a median survival time of 29.9 months. In the univariate analysis, the maximal diameter ≤20 mm (P = 0.0383), solitary lesion (P = 0.0352), and the complete remission after treatment (P = 0.00411) had a significantly better prognosis. A total of 27 of 35 patients (77.1%) had progressive disease (loco-regional failure [n = 9], distant metastasis [n = 7], and both loco-regional failure and distant metastasis [n = 11]). No patients had Grade 3 or greater mucositis.

Conclusion

Local field radiotherapy is a considerable treatment option for postoperative loco-regional recurrence of esophageal cancer.

The evolution of proton beam therapy: Current and future status

Proton beam therapy (PBT) has been increasingly used in a variety of cancers due to its excellent physical properties and superior dosimetric parameters. PBT may improve patient survival by improving the local tumor treatment rate while reducing injury to normal organs, which may result in fewer radiation-induced adverse effects. However, the significant cost of establishing and maintaining proton facilities cannot be overlooked. In addition, there has been significant controversy regarding routine application of this treatment in certain types of cancer. The challenges of PBT in the future mainly include the lack of basic clinical trials, unclear biological effects, immature imaging technology and miniaturization of imaging guidance. Overcoming these limitations may promote the rapid development of PBT. We herein provide an overview of the existing literature on the efficacy and toxicity of common oncological applications of proton beam therapy.

Successful corticosteroid treatment for pleural effusion due to radiation-induced pleuritis after chemoradiotherapy in a patient with esophageal cancer

Concurrent chemoradiotherapy (CRT) is one of the therapies with curative intent used to treat esophageal squamous cell carcinoma (ESCC), and overall survival of patients with esophageal carcinoma treated with CRT has improved. As the number of long-term survivors treated with concurrent CRT has increased, more patients experience late toxicities. A delayed adverse event, such as pleural effusion, is sometimes fatal, but little is known about its treatment. A 72-year-old man diagnosed with ESCC was treated with definitive CRT. He had a complete response to CRT, and 4 years later he complained of dyspnea, caused by pleural effusion. Diuretic agents and drainage of pleural effusion were not sufficiently effective in this case. After oral administration of 30 mg prednisolone, re-accumulation of fluid in the pleural space was controlled and the prednisolone dose was gradually tapered. Corticosteroids could be effective treatment for delayed pleural effusion after radiotherapy, and should be considered an option for treatment-refractory pleural effusion.

Bayesian variable selection for a semi-competing risks model with three hazard functions

A variable selection procedure is developed for a semi-competing risks regression model with three hazard functions that uses spike-and-slab priors and stochastic search variable selection algorithms for posterior inference. A rule is devised for choosing the threshold on the marginal posterior probability of variable inclusion based on the Deviance Information Criterion (DIC) that is examined in a simulation study. The method is applied to data from esophageal cancer patients from the MD Anderson Cancer Center, Houston, TX, where the most important covariates are selected in each of the hazards of effusion, death before effusion, and death after effusion. The DIC procedure that is proposed leads to similar selected models regardless of the choices of some of the hyperparameters. The application results show that patients with intensity-modulated radiation therapy have significantly reduced risks of pericardial effusion, pleural effusion, and death before either effusion type.

Long-term complications of definitive chemoradiotherapy for esophageal cancer using the classical method

Chemoradiation therapy is widely used to treat both inoperable and operable patients, and is less invasive than surgery. Although the number of long-term survivors who have received chemoradiation therapy is increasing, the long-term toxicity pattern and cumulative incidence of toxicity regarding this modality are poorly understood. Classically, chemoradiation therapy for esophageal cancer consists of an anterior-posterior field and a subsequent oblique boost field. We retrospectively analyzed patients who were treated with definitive chemoradiation therapy for esophageal cancer using this classical method from 1999 to 2008. For the assessment of toxicity, the National Cancer Institute Common Toxicity Criteria Version 3.0 was adopted. A total of 101 patients were analyzed. The median follow-up time was 16 months for all patients and 62 months for the surviving patients. Eleven patients experienced late toxicities of ≥Grade 3. Two patients died of late toxicities. The 3- and 5-year cumulative incidences for the first late cardiopulmonary toxicities of ≥Grade 3 were 17.4% and 20.8%, respectively. Cardiopulmonary effusions were observed within the first 3 years of completion of the initial treatment in seven out of eight patients. Sudden death and cardiac ischemia were observed over a 10-year period. Older age was found to be a risk factor for late toxicity after definitive chemoradiation therapy for esophageal cancer. Substantial toxicities were observed in patients who had received chemoradiation therapy for esophageal cancer using the classical method. To minimize the incidence of late toxicity, more sophisticated radiation techniques may be useful.

Radiation-induced heart disease in lung cancer radiotherapy: A dosimetric update

BACKGROUND

Radiation-induced heart disease (RIHD), which affects the patients' prognosis with both acute and late side effects, has been published extensively in the radiotherapy of breast cancer, lymphoma and other benign diseases. Studies on RIHD in lung cancer radiotherapy, however, are less extensive and clear even though the patients with lung cancer are delivered with higher doses to the heart during radiation treatment.

METHODS

In this article, after extensive literature search and analysis, we reviewed the current evidence on RIHD in lung cancer patients after their radiation treatments and investigated the potential risk factors for RIHD as compared to other types of cancers.

RESULT

Cardiac toxicity has been found highly relevant in lung cancer radiotherapy. So far, the crude incidence of cardiac complications in the lung cancer patients after radiotherapy has been up to 33%.

CONCLUSION

The dose to the heart, the lobar location of tumor, the treatment modality, the history of heart and pulmonary disease and smoking were considered as potential risk factors for RIHD in lung cancer radiotherapy. As treatment techniques improve over the time with better prognosis for lung cancer survivors, an improved prediction model can be established to further reduce the cardiac toxicity in lung cancer radiotherapy.

A survey of changing trends in modelling radiation lung injury in mice: bringing out the good, the bad, and the uncertain

Within this millennium there has been resurgence in funding and research dealing with animal models of radiation-induced lung injury to identify and establish predictive biomarkers and effective mitigating agents that are applicable to humans. Most have been performed on mice but there needs to be assurance that the emphasis on such models is not misplaced. We therefore considered it timely to perform a comprehensive appraisal of the literature dealing with radiation lung injury of mice and to critically evaluate the validity and clinical relevance of the research. A total of 357 research papers covering the period of 1970-2015 were extensively reviewed. Whole thorax irradiation (WTI) has become the most common treatment for studying lung injury in mice and distinct trends were seen with regard to the murine strain, radiation dose, intended pathology investigated, length of study, and assays. Recently, the C57BL/6 strain has been increasingly used in the majority of these studies with the notion that they are susceptible to pulmonary fibrosis. Nonetheless, many of these investigations depend on animal survival as the primary end point and neglect the importance of radiation pneumonitis and the anomaly of lethal pleural effusions. A relatively large variation in survival times of C5BL/6 mice is also seen among different institutions pointing to the need for standardization of radiation treatments and environmental conditions. An analysis of mitigating drug treatments is complicated by the fact that the majority of studies are limited to the C57BL/6 strain with a premature termination of the experiments and do not establish whether the treatment actually prevents or simply delays the progression of radiation injury. This survey of the literature has pointed to several improvements that need to be considered in establishing a reliable preclinical murine model of radiation lung injury. The lethality end point should also be used cautiously and with greater emphasis on other assays such as non-invasive lung functional and imaging monitoring in order to quantify specific pulmonary injury that can be better extrapolated to radiation toxicity encountered in our own species.

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.

Proton beam therapy in Japan: current and future status

The number of patients treated by proton beam therapy in Japan since 2000 has increased; in 2016, 11 proton facilities were available to treat patients. Notably, proton beam therapy is very useful for pediatric cancer; since the pediatric radiation dose to normal tissues should be reduced as much as possible because of the effect of radiation on growth, intellectual development, endocrine organ function and secondary cancer development. Hepatocellular carcinoma is common in Asia, and most of the studies of proton beam therapy for liver cancer have been reported by Japanese investigators. Proton beam therapy is also a standard treatment for nasal and paranasal lesions and lesions at the base of the skull, because the radiation dose to critical organs such as the eyes, optic nerves and central nervous system can be reduced with proton beam therapy. For prostate cancer, comparative studies that address adverse effects, safety, patient quality of life and socioeconomic issues should be performed to determine the appropriate use of proton beam therapy for prostate cancer. Regarding new proton beam therapy applications, experience with proton beam therapy combined with chemotherapy is limited, although favorable outcomes have been recently reported for locally advanced lung cancer, esophageal cancer and pancreatic cancer. Therefore, 'chemoproton' therapy appears to be a very attractive field for further clinical investigations. In conclusion, there are cost issues and considerations regarding national insurance for the use of proton beam therapy in Japan. Further studies and discussions are needed to address the use of proton beam therapy for several types of cancers, and for maintaining the quality of life of patients while retaining a high cure rate.

Clinical characteristics and dose-volume histogram parameters associated with the development of pleural effusions in non-small cell lung cancer patients treated with chemoradiation therapy

BACKGROUND

To investigate descriptive characteristics and dose metric (DM) parameters associated with development of pleural effusions (PlEf) in non-small cell lung cancer (NSCLC) treated with definitive chemoradiation therapy (CRT).

MATERIALS AND METHODS

We retrospectively assessed treatment records and follow-up imaging of 66 NSCLC patients to identify PlEf formation after CRT. PlEf association between mean heart dose (MHD), mean lung dose (MLD), heart V5-V60 (HV), and lung V5-V60 (LV) were evaluated using Cox Proportional Hazard Models.

RESULTS

A total of 52% (34 of 66 patients) of our population developed PlEf and the actuarial rates at 6 months, 12 months, and 18 months were 7%, 30%, and 42%, respectively. Median time to diagnosis was five months (range 0.06-27 months). The majority of PlEfs were grade one (67%) and developed at a median of four (0.06-13) months, followed by grade two (15%) at a median 11 (5-12) months, and grade three (18%) at a median of 11 (3-27) months. On multivariate analysis, increasing HV5-HV50, LV5-LV50, MHD, and MLD were associated with greater risk of PlEf. Higher grade PlEf was also associated with higher doses of radiation to the heart, while lung DM parameters were not significantly associated with higher PlEf grades. At five-months post-CRT, MHD of 25 Gy was associated with a 100% chance of grade one PlEf, an 82% risk of grade two PlEf, and a 19% risk of grade three PlEf.

CONCLUSIONS

Post-CRT PlEf is common in NSCLC with the majority being grade one. Increasing heart and lung irradiation was associated with increased risk of PlEf. Increasing heart irradiation also correlated with development of increasing grades of PlEf. The impact of potential cardiopulmonary toxicity and resultant PlEfs after CRT requires additional study.

Dosimetric evaluation of anatomical changes during treatment to identify criteria for adaptive radiotherapy in oesophageal cancer patients

BACKGROUND

Some oesophageal cancer patients undergoing chemotherapy and concomitant radiotherapy (chemoRT) show large interfractional anatomical changes during treatment. These changes may modify the dose delivered to the target and organs at risk (OARs). The aim of the presenwt study was to investigate the dosimetric consequences of anatomical changes during treatment to obtain criteria for an adaptive RT decision support system.

MATERIAL AND METHODS

Twenty-nine patients were treated with chemoRT for oesophageal and gastro-oesophageal junction cancer and set up according to daily cone beam computed tomography (CBCTs) scans. All patients had an additional replanning CT scan at median fraction number 10 (9-14), which was deformably registered to the original planning CT. Gross tumour volumes (GTVs), clinical target volumes (CTVs) and OARs were transferred to the additional CT and corrected by an exwperienced physician. Treatment plans were recalculated and dose to targets and OARs was evaluated. Treatment was adapted if the volume receiving 95% of the prescribed dose (V95%) coverage of CTV decreased > 1% or planning target volume (PTV) decreased by > 3%.

RESULTS

In total, nine adaptive events were observed: All nine were triggered by PTV V95% decrease > 3% [median 11% (5-41%)] and six of these were additionally triggered by CTV V95% decrease > 1% [median 5% (2-35%)]. The largest discrepancies were caused by interfractional baseline or amplitude shifts in diaphragm position (n = 5). Mediastinal (n = 6), oesophageal (n = 6) and bowel filling changes (n = 2) caused the remainder of the changes. For patients with dosimetric changes exceeding the adaptation limits, the discrepancies were confirmed by inspecting the daily CBCTs. In 31% of all patients, heart V30Gy increased more than 2% (maximum 5%). Only minor changes in lung dose or liver dose were seen.

CONCLUSION

Target coverage throughout the course of chemoRT treatment is compromised in some patients due to interfractional anatomical changes. Dose to the heart may increase as well.

Is cardiac toxicity a relevant issue in the radiation treatment of esophageal cancer?

PURPOSE

In recent years several papers have been published on radiation-induced cardiac toxicity, especially in breast cancer patients. However, in esophageal cancer patients the radiation dose to the heart is usually markedly higher. To determine whether radiation-induced cardiac toxicity is also a relevant issue for this group, we conducted a review of the current literature.

METHODS

A literature search was performed in Medline for papers concerning cardiac toxicity in esophageal cancer patients treated with radiotherapy with or without chemotherapy.

RESULTS

The overall crude incidence of symptomatic cardiac toxicity was as high as 10.8%. Toxicities corresponded with several dose-volume parameters of the heart. The most frequently reported complications were pericardial effusion, ischemic heart disease and heart failure.

CONCLUSION

Cardiac toxicity is a relevant issue in the treatment of esophageal cancer. However, valid Normal Tissue Complication Probability models for esophageal cancer are not available at present.

Symptomatic pericardial effusion after chemoradiation therapy in esophageal cancer patients

PURPOSE

We investigated clinical and treatment-related factors as predictors of symptomatic pericardial effusion in esophageal cancer patients after concurrent chemoradiation therapy.

METHODS AND MATERIALS

We reviewed 214 consecutive primary esophageal cancer patients treated with concurrent chemoradiation therapy between 2001 and 2010 in our institute. Pericardial effusion was detected on follow-up computed tomography. Symptomatic effusion was defined as effusion ≥grade 3 according to Common Terminology Criteria for Adverse Events v4.0 criteria. Percent volume irradiated with 5 to 65 Gy (V5-V65) and mean dose to the pericardium were evaluated employing dose-volume histograms. To evaluate dosimetry for patients treated with two-dimensional planning in the earlier period (2001-2005), computed tomography data at diagnosis were transferred to a treatment planning system to reconstruct three-dimensional plans without modification. Optimal dosimetric thresholds for symptomatic pericardial effusion were calculated by receiver operating characteristic curves. Associating clinical and treatment-related risk factors for symptomatic pericardial effusion were detected by univariate and multivariate analyses.

RESULTS

The median follow-up was 29 (range, 6-121) months for eligible 167 patients. Symptomatic pericardial effusion was observed in 14 (8.4%) patients. Dosimetric analyses revealed average values of V30 to V45 for the pericardium and mean pericardial doses were significantly higher in patients with symptomatic pericardial effusion than in those with asymptomatic pericardial effusion (P<.05). Pericardial V5 to V55 and mean pericardial doses were significantly higher in patients with symptomatic pericardial effusion than in those without pericardial effusion (P<.001). Mean pericardial doses of 36.5 Gy and V45 of 58% were selected as optimal cutoff values for predicting symptomatic pericardial effusion. Multivariate analysis identified mean pericardial dose as the strongest risk factor for symptomatic pericardial effusion.

CONCLUSIONS

Dose-volume thresholds for the pericardium facilitate predicting symptomatic pericardial effusion. Mean pericardial dose was selected based not only on the optimal dose-volume threshold but also on the most significant risk factor for symptomatic pericardial effusion.

Prognosis was not deteriorated by multiple primary cancers in esophageal cancer patients treated by radiotherapy

Esophageal cancer patients are often associated with multiple primary cancers (MPC). The aim of this study is to evaluate the effect of MPC on prognosis in esophageal cancer patients treated by radiotherapy. Between 2001 and 2008, esophageal cancer patients treated by definitive radiotherapy at Gunma Cancer Center were retrospectively reviewed. Exclusion criteria were preoperative or postoperative radiotherapy, palliative radiotherapy, follow-up of <6 months, radiation dose of <50 Gy and no information on MPC. We analyzed 167 esophageal cancer patients and 56 (33.5%) were associated with MPC. Gastric cancer was the most frequent tumor (38.2%), followed by head and neck cancer (26.5%). Median follow-up time was 31.5 months (range 6.1-87.3 months). Patients with MPC included more stage I/II esophageal cancer than those without MPC (66.1% vs. 36.9%, P < 0.01). The 5-year overall survival rate for esophageal cancer with MPC was relatively better than those without MPC (46.1% vs. 26.7%), although the difference did not reach statistical significance in univariate analysis (P = 0.09). Stage I/II esophageal cancer patients had a significantly better overall survival than stage III/IV patients (P < 0.01). Among esophageal cancer patients with MPC, there was no difference in overall survival between antecedent and synchronous cancer (P = 0.59). Our study indicated that the prognosis of esophageal cancer patients treated by radiotherapy was primarily determined by the clinical stage itself, but not the presence of MPC.

Advanced techniques in neoadjuvant radiotherapy allow dose escalation without increased dose to the organs at risk : Planning study in esophageal carcinoma

PURPOSE

The goal of this work was to investigate the potential of advanced radiation techniques in dose escalation in the radiotherapy (RT) for the treatment of esophageal carcinoma.

METHODS

A total of 15 locally advanced esophageal cancer (LAEC) patients were selected for the present study. For all 15 patients, we created a 3D conformal RT plan (3D-45) with 45 Gy in fractions of 1.8 Gy to the planning target volume (PTV1), which we usually use to employ in the neoadjuvant treatment of LAEC. Additionally, a 3D boost (as in the primary RT of LAEC) was calculated with 9 Gy in fractions of 1.8 Gy to the boost volume (PTV2) (Dmean) to a total dose of 54 Gy (3D-54 Gy), which we routinely use for the definitive treatment of LAEC. Three plans with a simultaneous integrated boost (SIB) were then calculated for each patient: sliding window intensity-modulated radiotherapy (IMRT-SIB), volumetric modulated arc therapy (VMAT-SIB), and helical tomotherapy (HT-SIB). For the SIB plans, the requirement was that 95 % of the PTV1 receive ≥ 100 % of the prescription dose (45 Gy in fractions of 1.8 Gy, D95) and the PTV2 was dose escalated to 52.5 Gy in fractions of 2.1 Gy (D95).

RESULTS

The median PTV2 dose for 3D-45, 3D-54, HT-SIB, VMAT-SIB, and IMRT-SIB was 45, 55, 54, 56, and 55 Gy, respectively. Therefore, the dose to PTV2 in the SIB plans was comparable to the 3D-54 plan. The lung dose in the SIB plans was in the range of the standard 3D-45, which is applied for neoadjuvant radiotherapy. The mean lung dose for the same plans was 13, 15, 12, 12, and 13 Gy, respectively. The V5 lung volumes were 71, 74, 79, 75, and 73 %, respectively. The V20 lung volumes were 20, 25, 16, 18, and 19 %, respectively.

CONCLUSION

New treatment planning techniques enable higher doses to be delivered for neoadjuvant radiotherapy of LAEC without a significant increase in the delivered dose to the organs at risk. Clinical investigations are warranted to study the clinical safety and feasibility of applying higher doses through advanced techniques in the neoadjuvant treatment of LAEC.

Detection of esophageal fiducial marker displacement during radiation therapy with a 2-dimensional on-board imager: analysis of internal margin for esophageal cancer

PURPOSE

To quantify the interfraction displacement of esophageal fiducial markers for primary esophageal cancer radiation therapy.

METHODS AND MATERIALS

Orthogonal 2-dimensional (2D) matching records fused to vertebrae were analyzed in clinically staged T1/2N0 esophageal cancer patients undergoing endoscopic clipping as fiducial metal markers. Displacement of the markers between the digitally reconstructed radiographs and on-board kilovoltage images during radiation therapy was analyzed according to direction and esophageal site.

RESULTS

Forty-four patients, with 81 markers (10 proximal, 42 middle, and 29 distal), underwent 367 2D matching sessions during radiation therapy. The mean (SD) absolute marker displacement was 0.26 (0.30) cm in the right-left (RL), 0.50 (0.39) cm in the superior-inferior (SI), and 0.24 (0.21) cm in the anterior-posterior (AP) direction. Displacement was significantly larger in the SI than in the RL and AP directions (P<.0001). In the SI direction, mean absolute displacements of the distal, middle, and proximal esophagus were 0.67 (0.45) cm, 0.42 (0.32) cm, and 0.36 (0.30) cm, respectively. Distal esophagus displacement was significantly larger than those of the middle and proximal esophagus (P<.0001). The estimated internal margin to cover 95% of the cases was 0.75 cm in the RL and AP directions. In the SI direction, the margin was 1.25 cm for the proximal and middle esophagus and 1.75 cm for the distal esophagus.

CONCLUSIONS

The magnitude of interfraction displacement of esophageal clips was larger in the SI direction, particularly in the distal esophagus, but substantial displacement was observed in other directions and at other esophageal sites. It is practical to take estimated movements into account with internal margins, even if vertebrae-based 2D matching is performed.