The comprehensive treatment of esophageal cancer has undergone tremendous changes with the advent of the era of targeted and immunotherapy. The optimization of comprehensive treatment strategies will become increasingly precise with the deep research on biomarkers related to the therapeutic effect of esophageal cancer. With the precise implementation of various treatment methods, the therapeutic effect of esophageal cancer is bound to be significantly improved.

Ultra-high dose-rate (FLASH) radiotherapy is a new mode of radiotherapy that can control tumors while significantly reducing damage to surrounding normal tissues. Since its official naming in 2014, FLASH radiotherapy research has continued to grow, and in 2019 it entered a period of exponential development. Studies have shown that electrons, photons, and protons can all induce the FLASH effect, but the proton beam can overcome the physical limitations of shallow incident depth and high penetration dose, which is considered to be the most effective solution. This article summarizes previous research results of FLASH proton therapy from the research at the cell, animal and clinical levels, and summarizes the hypothesis of the FLASH effect mechanism, aiming to provide reference for promoting the research and clinical transformation of FLASH proton therapy.

Ultra-high dose-rate (FLASH) radiotherapy is a new mode of radiotherapy that can control tumors while significantly reducing damage to surrounding normal tissues. Since its official naming in 2014, FLASH radiotherapy research has continued to grow, and in 2019 it entered a period of exponential development. Studies have shown that electrons, photons, and protons can all induce the FLASH effect, but the proton beam can overcome the physical limitations of shallow incident depth and high penetration dose, which is considered to be the most effective solution. This article summarizes previous research results of FLASH proton therapy from the research at the cell, animal and clinical levels, and summarizes the hypothesis of the FLASH effect mechanism, aiming to provide reference for promoting the research and clinical transformation of FLASH proton therapy.

Patients with oligometastatic prostate cancer based on accurate diagnosis should be given active treatment. We should optimize the benefit through tailored approaches encompassing systemic treatment, local therapy, and metastasis-directed therapy. The optimal combination and duration of systemic treatment are currently undefined. Combining new hormonal agents with androgen deprivation therapy is recommended. Most experts advocate a duration of hormonal therapy ranging from 18 to 36 months. Local therapy for the primary lesion, surgery or radiotherapy, has been clinically validated for its feasibility and effectiveness in oligometastatic prostate cancer patients. Stereotactic ablative radiation therapy for metastatic lesions ensures safe and reliable local control. In summary, maximal eradication of all visible active lesions may confer a survival benefit to these patients. We provide a comprehensive review for the treatment of oligometastatic hormone-sensitive prostate cancer, aiming to contribute insights for clinical diagnosis and treatment.

As a new therapeutic strategy for esophageal cancer, immunotherapy has attracted more and more attention. The completed and ongoing clinical trials of immunotherapy for esophageal cancer confirm the great potential of immune checkpoint inhibitors in esophageal cancer. Future research will focus on the combination of immunotherapy with existing or new therapeutic modalities and the identification of populations likely to benefit from immunotherapy.

Neoadjuvant chemoradiotherapy is the preferred treatment mode for the diagnosis and treatment of locally advanced operable esophageal carcinoma recommended by many guidelines. However, some problems remain to be further explored. In this article, current problems perplexing clinical practice were sorted out, aiming to provide constructive suggestions for the smooth development of neoadjuvant chemoradiotherapy for esophageal carcinoma in the future.

Objective:To compare positional and volumetric differences between the gross target volumes (GTV) delineated on three-dimensional CT (3D-CT) referencing 18F-FDG PET/CT and the GTV on the deformed image derived from 3D-CT and 18F-FDG PET/CT for primary thoracic esophageal cancer (EC). Methods:Seventy-two patients underwent chemoradiotherapy were enrolled. All the patients sequentially underwent 18F-FDG PET/CT scans for diagnosis and 3D-CT scans for simulation. The GTV 3D was delineated on 3D-CT without referencing 18F-FDG PET/CT. The GTV PET-ref was delineated on 3D-CT referencing 18F-FDG PET/CT. The GTV PET-regwas delineated on the deformed image derived from 3D-CT and 18F-FDG PET/CT by MIM deformable registration software. The differences in position, volume, length, conformity index (CI), and degree of inclusion (DI) of target volumes were compared, respectively. Results:The median volume of GTV 3D, GTV PET-ref, GTV PET-reg were 44.90, 40.36 and 41.15 cm 3, respectively. There was no statistical difference between the volumes of any two targets. The mean lengths of GTV 3D, GTV PET-ref, GTV PET-reg were 8.54, 9.29 and 8.38 cm, respectively. The length of GTV PET-ref was longer than that of GTV 3D ( t=2.134, P<0.05). The median DIs of GTV PET-ref, GTV PET-regin GTV 3D were 0.86, 0.82( Z=-2.741, P<0.05), and that of GTV 3D in GTV PET-ref, GTV PET-reg were 0.87, 0.84 ( Z=-1.429, P<0.05). The median CIs of GTV 3D in GTV PET-ref and GTV PET-reg were 0.72, 0.68 ( Z=2.756, P<0.05), and the difference was significant. The CIs of GTV 3D and GTV PET-ref, GTV 3D and GTV PET-reg, GTV PET-ref and GTV PET-reg had significant negative correlation with the distance of target centers. Conclusions:There was no significant difference between GTV contoured on three-dimensional CT (3D-CT) referencing 18F-FDG PET/CT and the GTV on the deformed image derived from 3D-CT and 18F-FDG PET/CT either in volume size or in spatial position. Therefore, it is recommended that radiation oncologists can refer to the recent diagnostic PET/CT when delineating the gross target volume for primary thoracic esophageal cancer.

Objective To compare the dosimetric and delivery efficiency between intensity-modulated radiation therapy (IMRT) plans based on Halcyon and Trilogy accelerator.Methods Clinical data of 12 patients with cervical cancer receiving Trilogy platform-based IMRT were retrospectively analyzed.The target area and organ at risk were introduced into the Eclipse version 15.1 TPS.The Halcyon-based IMRT was re-designed.The dose coverage of target area and organs at risk,monitor unit (MU) efficiency,delivery time and segment area and the differences between the proximal and distal segment area were statistically compared between two IMRT plans.Results The Halcyon treatment platform could meet the clinical objectives.Dose distribution of the target area was similar to that of the Trilogy plan (P＞O.05).The volumes in the bladder and rectum receiving 30 Gy and the volumes in the left femoral head receiving 20 Gy of Halcyon plan and the mean dose (D) of bladder,rectum and left femoral head were significantly lower compared with those of the Trilogy plan (P=0.001-0.043).The MUs of the Halcyon plan was 2 316.7± 209.7,significantly higher than 1 692.5± 259.5 of the Trilogy plan (P=0.000).The delivery time significantly differed between the Halcyon [(3.01±0.28) min] and Trilogy [(12.38± 1.49) min] (P=0.000).The average segment area of Halcyon plan for proximal and distal MLC was (43.7±32.5) cm2 and (28.8±25.4) cm2,the average segment area of Trilogy plan was (25.7±16.8) cm2,the ratio of the proximal and distal segment area was 1.73±0.43,ranging from 0.71 to 6.28.Conclusions Halcyon treatment platform can meet the clinical requirements and reduce the dosage coverage of normal tissues with better delivery efficiency.The ratio of proximal and distal segment areas should be considered during the plan design.

Objective To analyze the dosimetric and delivery efficiency differences between IMRT plans based on Halcyon and Trilogy Accelerator for left side breast cancer.Methods A total of 10 patients with left side breast cancer based on the Trilogy platform were retrospectively analyzed.For each patient,plan based on Halcyon was redesigned using Eclipse Version 15.1 TPS.In order to evaluate plan quality,dose coverage of target and dose to organs at risk,monitor unit efficiency,segment size and delivery time were compared.Results Halcyon treatment platform could meet the clinical objective.Dose distribution of the target volume had no significant difference with the Trilogy plans (P＞0.05).Volumes receiving 10 Gy,20 Gy and D of the left lung were significantly reduced(Z=-2.22--1.78,P＜0.05).V5 of heart for Halcyon and Trilogy was(27.80±7.66)％ and (23.18±8.19)％,respectively(Z=-0.71,P＜0.05),while D was (7.03± 1.8)Gy and(7.11±2.40)Gy,respectively(P＞0.05).Halcyon increased the monitor unit from 1 526.2±227.7 by Trilogy to 1 770.5±383.9(Z=-0.71,P＜0.05),but decreased the delivery time from (12.38± 1.49) min by Trilogy to (3.01 ±0.28) min (Z =-3.42,P＜ 0.05).Conclusion Halcyon treatment platform can meet the clinical requirements,reduce dose to normal tissue with high delivery efficiency.

Modern medical imaging techniques,such as computed tomorgraphy (CT),magnetic resonance imaging (MRI) and position emission tomorgraphy/computed tomorgraphy (PET-CT) can accurately delineate the gross target volume (GTV) of hepatocellular carcinoma (HCC).Comparison of postoperative pathological subclinical lesions,imaging and clinical parameters contributes to the precise delineation of clinical target volume (CTV).Moreover,radiotherapy-assisted techniques,such as fourdimensional computed tomography (4DCT),compression of abdomen,active breathing control and respiratory gating,can minimize the internal target volume (ITV).In addition,immobilization with vacuum cushion and body membrane can reduce the set-up error,minimize the planning target volume (PTV) and avoid or decrease the irradiation error or missing irradiation.All these approach can minimize the target volume,elevate the dose and reduce the complications during radiotherapy for HCC.In this article,the research progress on the target delineation for external beam radiotherapy in HCC patients was reviewed.