Radiation-Induced Liver Injury in Three-Dimensional Conformal Radiation Therapy (3D-CRT) for Postoperative or Locoregional Recurrent Gastric Cancer: Risk Factors and Dose Limitations

A qualitative, quantitative and dosimetric evaluation of a machine learning-based automatic segmentation method in treatment planning for gastric cancer

PURPOSE

To investigate the performance of a machine learning-based segmentation method for treatment planning of gastric cancer.

MATERIALS AND METHODS

Eighteen patients planned to be irradiated for gastric cancer were studied. The target and the surrounding organs-at-risk (OARs) were manually delineated on CT scans. A machine learning algorithm was used for automatically segmenting the lungs, kidneys, liver, spleen and spinal cord. Two radiation oncologists evaluated these contours and performed the required editing. The accuracy of the auto-segmented contours relative to manual outlines was evaluated by calculating the dice similarity coefficient (DSC), Jaccard score (JS), sensitivity and precision. VMAT plans were initially created on manual contours (MCPlans) and, then, on edited and unedited auto-segmented contours (ACedPlans). Dose parameters of the OARs and target volume derived from the different treatment plans were statistically compared.

RESULTS

The 24.6 % of the auto-segmented contours were acceptable and 40.5 % needed changes related to stylistic deviations. Minor editing was applied in 34.1 % of these contours. The mean values of the DSC, JS, sensitivity and precision associated with the comparison of the manual outlines and the contour set including edited and unedited auto-segmented contours were 0.91-0.97, 0.84-0.94, 0.92-0.97 and 0.91-0.97, respectively. No significant differences were found for fifteen out of eighteen examined dosimetric parameters derived from MCPlans and ACedPlans (p > 0.05). These parameters from the MCPlans agreed well with those from ACedPlans based on the Bland-Altman test.

CONCLUSIONS

The qualitative, quantitative and dosimetric analysis highlighted the clinical acceptability of a machine learning-based segmentation method for radiotherapy of gastric cancer.

Radiation-induced liver disease mimicking liver metastasis after low-dose hepatic irradiation during radiotherapy for gastric mucosa-assisted lymphoid tissue lymphoma: A case report

RATIONALE

Radiation-induced liver disease (RILD) is an established complication of hepatic irradiation that is typically reported in patients receiving high-dose radiotherapy for hepatocellular carcinoma or liver metastases. However, RILD can also occur after unintentional low-dose liver exposure during radiotherapy for other gastrointestinal malignancies when careful precautions are not taken.

PATIENT CONCERNS

We report the case of a 44-year-old woman with gastric mucosa-associated lymphoid tissue lymphoma who underwent salvage radiotherapy administered to the entire stomach. One month after completing this radiotherapy, computed tomography and magnetic resonance imaging of the patient's abdomen revealed a 4 cm lesion in the left lateral liver segment, suggestive of metastasis.

DIAGNOSES

An ultrasound-guided biopsy was performed, and the histopathological findings were consistent with those of RILD.

INTERVENTIONS

Conservative management was pursued with close monitoring of liver function tests.

OUTCOMES

The patient's imaging findings and liver enzyme levels normalized approximately 3 months after the initial diagnosis.

LESSONS

This case highlights the importance of considering RILD in the differential diagnosis of new hepatic lesions detected after radiotherapy, even in patients with low-dose liver exposure within generally acceptable limits. Careful correlation with the radiotherapy plan is crucial to avoid misdiagnosing RILD as metastatic disease and to guide appropriate management.

Concomitant Irradiation to Checkpoint Inhibitor Therapy of Hepatocellular Carcinoma Patients: A Systematic Retrospective, Single-Center Analysis

INTRODUCTION

Immunotherapy has been established as the standard treatment option for patients with advanced hepatocellular carcinoma (aHCC). Despite the increased efficacy, disease progression occurs in a relevant proportion of patients even after an objective response. Combination concepts with locoregional therapy are currently under investigation for hepatic disease but are also in discussion for the control of distant metastasis. Radiotherapy is a highly effective treatment modality for local tumor control. It is also thought to increase the efficacy of checkpoint inhibition and sensitize distant lesions to the effects of immunotherapy, but may potentially increase adverse effects. In our center, few patients with aHCC treated with immune checkpoint inhibitors (ICIs) received concomitant radiotherapy for symptom or disease control. The aim of this study was to retrospectively analyze adverse effects and efficacy of concomitant radiotherapy in patients with aHCC treated with checkpoint inhibition.

METHODS

To this aim, patients who received a combination of ICI and radiotherapy in our institution were retrospectively considered for analysis. The predefined inclusion criterion was radiotherapy after initiated checkpoint inhibition and continuation of ICI therapy for at least 8 weeks. Adverse effects and efficacy measurements were performed according to local standards.

RESULTS

The database search of 2016-2021 revealed six consecutive patients fulfilling the predefined criteria for concomitant ICI and radiotherapy. Three patients received high-dose-rate brachytherapy (15 Gy) to treat progredient hepatic lesions. Two patients received stereotactic body radiotherapy (SBRT) (25-30 Gy) for symptom control, and 1 patient received brachytherapy and SBRT to treat metastases. No severe adverse events were reported in the period (<6 months) after concomitant radiotherapy. In 5 out of 6 cases, long-term tumor control could be achieved by this therapeutic combination.

CONCLUSION

A good efficacy of concomitant radiotherapy and checkpoint inhibition has been achieved with no safety concerns. Further investigations should evaluate the safety, appropriate clinical context, and efficacy of this promising approach.

Investigation of the anti-oxidative and anti-inflammatory effects of melatonin on experimental liver damage by radiation

Radiotherapy is one of the inevitable treatment approaches for several types of cancer. We aimed to show the protective and therapeutic effects of daily use of melatonin on liver tissues subjected to a single dose of 10 Gy (gamma-ray) total body radiation. Rats were divided into 6 groups, of which 10 were in each: control, sham, melatonin, radiation, radiation+melatonin, and melatonin+radiation. The rats received 10 Gy of external radiation throughout their entire bodies. The rats were given 10 mg/kg/day of melatonin intraperitoneally before or after radiation treatment, depending on the group. Histological methods, immunohistochemical analysis (Caspase-3, Sirtuin-1, α-SMA, NF_ΚB-p65), biochemical analysis by ELİSA (SOD, CAT, GSH-PX, MDA, TNF-α, TGF-β, PDGF, PGC-1α) and the Comet assay as a marker of DNA damage were applied to the liver tissues. Histopathological examinations showed structural changes in the liver tissue of the radiation group. Radiation treatment increased the immunoreactivity of Caspase-3, Sirtuin-1 and α-SMA, but these effects were relatively attenuated in the melatonin-treated groups. The melatonin+radiation group had statistically significant results close to those of the control group, in terms of Caspase-3, NF_ΚB-p65 and Sirtuin-1 immunoreactivity. In melatonin treated groups, hepatic biochemical markers, MDA, SOD, TNF-α, TGF-β levels, and DNA damage parameters were decreased. Administration of melatonin before and after radiation has beneficial effects, but using it before radiation may be more efficient. Accordingly, daily melatonin usage could mitigate ionizing radiation induced damage.

Regulation of radiation-induced liver damage by modulation of SIRT-1 activity: In vivo rat model

Silent information regulator 1 (SIRT-1), a nicotinamide adenine dinucleotide-dependent deacetylase, was found to regulate cell apoptosis, inflammation, and oxidative stress response in living organisms. Therefore, the role of SIRT-1 in regulating forkhead box O/poly ADP-ribose polymerase-1 (FOXO-1/PARP-1) signaling could provide the necessary validation for developing new pharmacological targets for the promotion or inhibition of SIRT-1 activity toward radiation sensitivity. In the present study, the SIRT-1 signaling pathway is being investigated to study the possible modulatory effect of resveratrol (RSV, SIRT-1 activator) versus nicotinamide (NAM, SIRT-1 inhibitor) in case of liver damage induced by whole-body gamma irradiation. Rats were exposed to 6 Gy gamma radiation after being pretreated with either RSV (10 mg/kg/day) or NAM (100 mg/kg/day) for 5 days, and subsequent examining hepatic morphological changes and apoptotic markers were assessed. The expression of SIRT-1, FOXO-1, and cleaved PARP-1 in the liver was analyzed. RSV improved radiation-induced apoptosis, mitochondrial dysfunction, and inflammation signified by low expression of caspase-3, lactate dehydrogenase, complex-I activity, myeloperoxidase, and total nitric oxide content. RSV increased the expression of SIRT-1, whereas cleaved PARP-1 and FOXO-1 were suppressed. These protective effects were suppressed by inhibition of SIRT-1 activity using NAM. These findings suggest that RSV can attenuate radiation-induced hepatic injury by reducing apoptosis and inflammation via SIRT-1 activity modulation.

Relationship between absorbed dose and changes in liver volume after chemoradiotherapy for esophageal cancer

PURPOSE

The liver is the largest organ in the abdomen and is often irradiated in radiotherapy for non-hepatic malignancies. As most of the studies on changes in liver volume are on hepatocellular carcinoma based on liver dysfunction, there are few studies on healthy liver. In this study, we investigated the relationship between absorbed dose and changes in liver volume after chemoradiotherapy for esophageal cancer in patients without apparent pre-treatment liver dysfunction.

MATERIALS AND METHODS

Liver volume was compared between pre-treatment, acute (< 4 months) and late post-treatment (≥ 4 and < 13 months) phases in 12 patients using abdominal plain CT images. Volume changes were evaluated separately for the right and left lobes. We investigated the relationship between the volume change and V_xGy (percentage of volume received x Gy or more dose). In addition, volume change for each absorbed dose was investigated using deformable image registration.

RESULTS

The volume of the left lobe showed a significant decrease between pre-treatment and acute post-treatment phases (p < 0.001), while the volume of right lobe and between acute and late post-treatment phase of left lobe did not. The mean value of the volume reduction rate of the left lobe was 51.1% and equivalent to the mean value of V_30Gy. As a result of the volume change for each absorbed dose, the volume reduction rate increased as the absorbed dose increased, and a significant volume loss was observed at doses above 11 Gy.

CONCLUSION

Volume of the liver significantly decreased only in the acute phase after chemoradiotherapy for esophageal cancer. The tolerable dose for a healthy liver is generally considered to be 30 Gy, but attention should be paid to lower doses to avoid radiation-induced liver injury.

Automatic Radiobiological Comparison of Radiation Therapy Plans: An Application to Gastric Cancer

(1) Aim: This study was conducted to radiobiologically compare radiotherapy plans for gastric cancer with a newly developed software tool. (2) Methods: Treatment planning was performed on two computational phantoms simulating adult male and female patients. Three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans for gastric cancer were generated with three-photon beam energies. The equivalent uniform dose (EUD), tumor control probability (TCP) of the target and normal tissue control probability (NTCP) of eight different critical organs were calculated. A new software was employed for these calculations using the EUD-based model and dose-volume-histogram data. (3) Results: The IMRT and VMAT plan led to TCPs of 51.3-51.5%, whereas 3D-CRT gave values up to 50.2%. The intensity-modulated techniques resulted in NTCPs of (5.3 × 10^-6-3.3 × 10^-1)%. The corresponding NTCPs from 3D-CRT were (3.4 × 10^-7-7.4 × 10^-1)%. The above biological indices were automatically calculated in less than 40 s with the software. (4) Conclusions: The direct and quick radiobiological evaluation of radiotherapy plans is feasible using the new software tool. The IMRT and VMAT reduced the probability of the appearance of late effects in most of the surrounding critical organs and slightly increased the TCP compared to 3D-CRT.

Radiation Induced Liver Injury: Collateral Damage Radiologically Simulating Interval Metastasis in Carcinoma Esophagus; a Diagnostic Dilemma Resolved Through Liver Biopsy

F-18-fluorodeoxyglucose positron emission tomography (18-FDG PET/CT) is increasingly being used in patients with cancer, both for baseline staging and for evaluation of treatment response. However, in patients with incidental irradiation of the liver during radiotherapy, particularly for lower gastrointestinal tract cancers, increased focal F-18-fluorodeoxyglucose positron emission tomography avidity may be the result of collateral radiation induced liver damage rather than metastases. Awareness of this pathologic entity and correlation with with other imaging, clinical and laboratory findings including liver biopsy is vital to avoid misinterpretation and overstaging of the carcinoma in these patients. We encountered such a scenario in an elderly female patient with distal esophageal squamous cell carcinoma patient, who developed F-18-fluorodeoxyglucose positron emission tomography avid left lobe liver lesion post neoadjuvant radiotherapy, simulating interval metastasis. A liver biopsy ruled out malignancy and helped to clinch the correct diagnosis of radiation induced liver injury.

Impact of adjuvant radiotherapy on biological and clinical parameters in right-sided breast cancer

PURPOSE

In patients with right-sided breast cancer (BC) the liver might be partially irradiated during adjuvant radiotherapy (RT). Thus, we performed a prospective observational study to evaluate the dose delivered to the liver, and its potential biological impact.

PATIENTS AND METHODS

We enrolled 34 patients with right-sided BC treated with adjuvant RT. The RT schedules were either the Canadian (42.5Gy in 16 fx) or standard fractionated (50Gy in 25 fx) regimen respectively with 9 (26.5%) and 25 (73.5%) patients each, ± a boost of 10-16Gy. Each patient had a complete blood count and liver enzymes analysis, before starting and during the last week of treatment.

RESULTS

A significant decrease in white blood cells and thrombocytes counts was observed during RT. We observed a significant correlation between certain hepatic parameters and the volume of the irradiated liver and/or the mean liver dose. A significant correlation between the volume of the right lung and the liver mean dose was found (P=0.008). In the bivariate analysis, a significant correlation between fatigue and the white blood cell count's evolution was observed (P<0.025).

CONCLUSION

With the standard RT technique, incidental irradiation of the liver was documented in a large number of patients, and some significant hepatic parameters alterations were observed, without an apparent clinical impact, but this study cannot exclude them. The liver mean dose was correlated with the right lung volume suggesting that deep inspiration breath hold (DIBH) techniques may represent a way to decrease the liver dose. These findings need to be evaluated in further larger studies.

Patterns of recurrence after curative D2 resection for gastric cancer: Implications for postoperative radiotherapy

BACKGROUND

High-quality randomized controlled trials have demonstrated the benefit of radiotherapy (RT) in patients with radical resected gastric cancer (GC), however, utilization rates of postoperative RT remain remarkably low. Patterns, incidences, and time of recurrence provide biological bases for clinical monitoring of GC patients and guiding potential complementary therapies. Thus, the aim of this study is to understand the location of locoregional recurrence which may allow individualized RT strategies and minimize radiation-related toxic effects.

METHODS

A relatively large sample of GC patients in a single institution who had undergone curative D2 resection was retrospectively reviewed and the relevant recurrence patterns were illustrated. Independent recurrence-related risk factors were analyzed by logistic regression analysis. New logistic regression models were further developed to predict the probability of recurrence.

RESULTS

Overall, among 776 GC patients who had continuous and complete follow-up data, 300 cases relapsed after curative resection. Lymphovascular invasion, lymph node metastases, and tumor stage were indicators for early recurrence. Peritoneal, regional, local, and distant recurrence initially occurred in 51 (6.6%), 151 (19.4%), 56 (7.2%), and 164 (21.1%) patients, respectively. Among patients with regional recurrence, the most common sites were lymph node stations 16a2, 8, 12, 16b1, and 9. Remnant stomach recurrence was not so prominent that it seemed reasonable to be excluded from an irradiation field for patients with negative surgical/pathologic margins.

CONCLUSIONS

For GC patients who underwent radical D2 resection, distant and regional recurrences were still common. Besides, optimizing regional control of lymph nodes outside the D2 dissected area was crucial for rational design of the RT field. Furthermore, the new logistic regression models might act as useful tools to evaluate recurrence risk and determine which patients should receive postoperative chemoradiotherapy.

Outcome of postoperative radiation therapy for cholangiocarcinoma and analysis of dose-volume histogram of remnant liver

The aim of this study was to analyze dose-volume histogram (DVH) of the remnant liver for postoperative cholangiocarcinoma (CCA) patients, to find toxicity rates, and to confirm efficacy of postoperative radiation therapy (RT).Thirty-two postoperative CCA patients received partial liver resection and postoperative RT with curative intent. The "liver reduction rate" was calculated by contouring liver volume at computed tomography (CT) just before the surgery and at CT for planning the RT. To evaluate late toxicity, the radiation-induced hepatic toxicity (RIHT) was determined by the common terminology criteria for adverse events toxicity grade of bilirubin, aspartate transaminase, alanine transaminase, alkaline phosphatase, and albumin, and was defined from 3 months after RT until liver metastasis was revealed. The radiation-induced liver disease (RILD) was also evaluated.Tumor stages were distributed as follows: I: 1, II: 8, IIIA: 1, IIIB: 6, IIIC: 14, IVA: 2. Median prescribed total dose was 50 Gy. Median follow-up time was 27 months. Two-year overall survival (OS): 72.4%, disease-free survival: 47.7%, local control: 65.3%, and the median survival time was 40 months. The median "liver reduction rate" was 21%. The OS had statistically significant difference in nodal status (P = .032) and "liver reduction rate" >30% (P = .016). In the association between the ≥grade 2 RIHT and DVH, there were significantly differences in V30 and V40 (P = .041, P = .034), respectively. The grade ≥2 RIHT rates differ also significantly by sex (P = .008). Two patients (6.2%) were suspected of RILD.We suggest that RT for remnant liver should be considered the liver V30, V40 to prevent radiation-induced liver dysfunction.

Adjuvant Radiochemotherapy versus Chemotherapy Alone for Gastric Cancer: Implications for Target Definition

The INT0116 trial was a milestone study and laid the foundation for the adjuvant radiotherapy (RT) associated to concurrent chemotherapy (CT) for the treatment of gastric cancer (GC) after gastrectomy. However, it is still controversial whether adding RT to CT could further benefit D2-dissected GC patients. The ARTIST trial indicated that the addition of RT to CT did not have a positive impact on disease-free survival (DFS). Nevertheless, in a subgroup of 396 patients with positive pathological lymph nodes, combined treatment with RT was superior to CT alone. A similar randomized Chinese trial confirmed the superiority of adding RT to CT in terms of DFS for patients with D2 lymphadenectomy. However, several previous randomized studies provided inconsistent results with the benefits of combined treatment of RT and CT. The inconsistent results of several studies may be due to the differences between tumor epidemiology, treatment policies, and treatment outcomes. During the past decade, major progress in accurate target delineation utilizing RT technology has been observed. However, even though the use of adjuvant RT doubled after the INT-0116 trial results became public, the fraction of patients receiving adjuvant RT was still low according to the SEER database. The low rate of adjuvant RT can partially be explained by concern over toxicity while undergoing RT. Several studies have also defined the specific location of locoregional recurrence for postoperative RT in GC, but these studies are still limited. A number of retrospective studies demonstrated that the most prevalent nodal recurrence was outside the D2 dissection field. In order to overcome the restricted nature of a retrospective study and provide more individual radiation field determination, additional large-scale prospective multicenter studies are required to evaluate the optimal RT target.

Role of rational diet in postoperative treatment of gastric cancer and application prospect of traditional Chinese medicine diet

The toxic side effects of postoperative radiotherapy and chemotherapy in gastric cancer (GC) often cause patients to have cancer cachexia and poor quality of life. Dietary adjuvant therapy can significantly promote GC patients to recover the body function, alleviate inflammation, improve anticancer treatment tolerance, improve postoperative quality of life and prolong survival. Given the advantages of diet in the postoperative treatment of GC, this paper discusses the role of modern medicine's elemental nutrition diet and traditional Chinese medicine diet in the postoperative treatment of GC, which can help clinicians better understand traditional Chinese medicine treatment in relieving the overall dysfunction of the body. Furthermore, the combination of traditional Chinese medicine diet with the modern medical nutrition diet evaluation system can expand the use of traditional Chinese medicine diet in the clinical treatment of GC.

A Case of Liver Injury Mimicking Metastasis After Gamma Knife Therapy for Lung Cancer: Evaluating by 18F-FDG PET/CT

A 52-year-old man presented a mixed low-density lesion with high FDG uptake in hepatic segment VIII after gamma knife therapy for lung cancer, which was easily misdiagnosed as hepatic metastasis. Follow-up PET/CT assessment demonstrated that the hepatic lesion was barely observed and without FDG accumulation 5 months after radiotherapy. This case suggests that a new FDG-avid lesion at PET/CT after radiotherapy for lung cancer can be caused by radiation-induced liver injury. Knowledge of its imaging characteristics and nature course evaluated by follow-up PET/CT is critical to avoid misinterpretation of this lesion as metastases.

Evaluation of Blood Parameters Alteration Following Low-dose Radiation Induced by Myocardial Perfusion Imaging

INTRODUCTION

With increasing the usage of myocardial perfusion imaging (MPI) for the diagnosis of ischemic heart disease, we aimed to evaluate the side effects of low-dose radiation induced by this technique on blood elements, especially proteins and liver function factors.

MATERIAL AND METHODS

40 eligible patients (Mean age: 54.62±10.35, 22 female and 18 male), who had referred to the nuclear medicine department for MPI from May till August 2014, were enrolled in the study. A blood sample was taken from each patient just before and 24 hours after the injection of 740Mbq of Tecnetium-99m Methoxy isobutyl isonitrile (99mTc-MIBI) in the rest phase of the MPI in a reference medical laboratory; blood tests included total protein (TP), albumin (Alb), globulin (Glo), aspartate aminotransferase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), direct bilirubin (D.Bili), total bilirubin (T.Bili), serum iron (SI), total iron bounding capacity (TIBC), Albumin globulin ratioA/G ratio), and complete blood count (CBC).

RESULTS

Injection of 740Mbq99mTc-MIBI caused a significant increase in serum levels of AST (p= 0.001), ALT (p= 0.001), SI (p= 0.030), TIBC (p= 0.003) and A/G Ratio (p= 0.020). However, following radiotracer injection, a significant decrease was noted in the serum levels of TP (p= 0.002), Alb (p= 0.014), Glo(p= 0.002), ALP (p= 0.001), D.Bili (p= 0.003) and T.Bili (p= 0.000).

CONCLUSION

Due to increased usage of MPI, our data highlights the importance of monitoring the clinical and paraclinical effects of the procedure on vital organs and physiological pathways to reduce their adverse effects.

Low dose irradiation facilitates hepatocellular carcinoma genesis involving HULC

Irradiation exposure positive correlates with tumor formation, such as breast cancer and lung cancer. However, whether low dose irradiation induces hepatocarcinogenesis and the underlying mechanism remain poorly defined. In the present study, we reported that low dose irradiation facilitated the proliferation of hepatocyte through up-regulating HULC in vitro and in vivo. Low dose irradiation exposure elevated HULC expression level in hepatocyte. Deletion of heightened HULC erased the cells growth accelerated following low dose irradiation exposure. CDKN1, the neighbor gene of HULC, was down-regulated by overexpression of HULC following low dose irradiation exposure via complementary base pairing, resulting in promoting cell cycle process. Thus, our findings provide new insights into the mechanism of low dose irradiation-induced hepatocarcinogenesis through HULC/CDKN1 signaling, and shed light on the potential risk of low dose irradiation for the development of hepatocellular carcinoma in pre-clinical settings.

Radiation-induced liver disease: current understanding and future perspectives

Although radiotherapy (RT) is used for the treatment of cancers, including liver cancer, radiation-induced liver disease (RILD) has emerged as a major limitation of RT. Radiation-induced toxicities in nontumorous liver tissues are associated with the development of numerous symptoms that may limit the course of therapy or have serious chronic side effects, including late fibrosis. Although the clinical characteristics of RILD patients have been relatively well described, the understanding of RILD pathogenesis has been hampered by a lack of reliable animal models for RILD. Despite efforts to develop suitable experimental animal models for RILD, current animal models rarely present hepatic veno-occlusive disease, the pathological hallmark of human RILD patients, resulting in highly variable results in RILD-related studies. Therefore, we introduce the concept and clinical characteristics of RILD and propose a feasible explanation for RILD pathogenesis. In addition, currently available animal models of RILD are reviewed, focusing on similarities with human RILD and clues to understanding the mechanisms of RILD progression. Based on these findings from RILD research, we present potential therapeutic strategies for RILD and prospects for future RILD studies. Therefore, this review helps broaden our understanding for developing effective treatment strategies for RILD.

Human cytotoxic T-lymphocyte membrane-camouflaged nanoparticles combined with low-dose irradiation: a new approach to enhance drug targeting in gastric cancer

Cell membrane-derived nanoparticles are becoming more attractive because of their ability to mimic many features of their source cells. This study reports on a biomimetic delivery platform based on human cytotoxic T-lymphocyte membranes. In this system, the surface of poly-lactic-co-glycolic acid nanoparticles was camouflaged using T-lymphocyte membranes, and local low-dose irradiation (LDI) was used as a chemoattractant for nanoparticle targeting. The T-lymphocyte membrane coating was verified using dynamic light scattering, transmission electron microscopy, and confocal laser scanning microscopy. This new platform reduced nanoparticle phagocytosis by macrophages to 23.99% (P=0.002). Systemic administration of paclitaxel-loaded T-lymphocyte membrane-coated nanoparticles inhibited the growth of human gastric cancer by 56.68% in Balb/c nude mice. Application of LDI at the tumor site significantly increased the tumor growth inhibition rate to 88.50%, and two mice achieved complete remission. Furthermore, LDI could upregulate the expression of adhesion molecules in tumor vessels, which is important in the process of leukocyte adhesion and might contribute to the localization of T-lymphocyte membrane-encapsulated nanoparticles in tumors. Therefore, this new drug-delivery platform retained both the long circulation time and tumor site accumulation ability of human cytotoxic T lymphocytes, while local LDI could significantly enhance tumor localization.

Dosimetric Comparison of Three Different Radiotherapy Techniques in Antrum-Located Stomach Cancer

Background:

The current optimal radiotherapy (RT) planning technique for stomach cancer is controversial. The design of RT for stomach cancer is difficult and differs according to tumor localization. Dosimetric and clinical studies have been performed in patients with different tumor localizations. This may be the main source of inconsistencies in study results. For this reason, we attempted to find the optimal RT technique for patients with stomach cancer in similar locations.

Methods:

This study was based on the computed tomography datasets of 20 patients with antrum-located stomach cancer. For each patient, treatments were designed using physical wedge-based conformal RT (WB-CRT), field-in-field intensity-modulated RT (FIF-IMRT), and dynamic intensity-modulated RT (IMRT). The techniques were compared in terms of expected target volume coverage and the dose to organs at risk (OAR) using a dose-volume histogram analysis.

Results:

FIF-IMRT was the most homogenous technique, with a better homogeneity index than WBCRT (p<0.001) or IMRT (p<0.001). However, IMRT had a better conformity index than WBCRT (p<0.001) or FIF-IMRT (p<0.001). Additionally, all OAR, including the kidneys, liver, and spinal cord, were better protected with IMRT than with WBCRT (p=0.023 to <0.001) or FIF-IMRT (p=0.028 to <0.001).

Conclusions:

In comparison to FIF-IMRT and WBCRT, IMRT appears to be the most appropriate technique for antrum-located stomach cancer. To establish whether IMRT is superior overall will require clinical studies, taking into account differences in both tumor localization (cardia, body, and antrum) and organ movement in patients with stomach cancer.