Evaluation of the dosimetric impact of applying flattening filter-free beams in intensity-modulated radiotherapy for early-stage upper thoracic carcinoma of oesophagus

Dose-volume comparison of intensity modulated proton therapy and volumetric modulated arc therapy for cervical esophageal cancer

Proton therapy for cervical esophageal cancer has many issues to be considered, such as the physiological curvature of the spine and the large range change from the neck to the trunk. We clarified the dosimetric characteristics of intensity modulated proton therapy (IMPT) for cervical esophageal cancer by comparing with volumetric modulated arc therapy (VMAT). Ten patients with cervical esophageal cancer were retrospectively planned for VMAT, 2-field IMPT (2F-IMPT), and 3-field IMPT (3F-IMPT). All plans were optimized to reach clinically acceptable levels. For planning target volume (PTV) coverage, 95% of the PTV should be covered by 95% of the prescription dose, unless the spinal cord limit is violated. The organs at risk included the lung, spinal cord, larynx, skin, and whole body. The prescription dose was 60 Gy relative biological effectiveness (RBE) in 30 fractions to the PTV. We compared the results according to dose-volume metrics. Significant dose reductions were achieved at lung doses, especially at low dose volumes of 20 Gy RBE or less in IMPT plans compared with VMAT plans (p < 0.05). Although the spinal cord PRV was below the tolerance level, the results were also significantly higher in VMAT plans than in IMPT plans (p < 0.001). Spinal cord PRV Dmean was significantly higher in 3F-IMPT than in 2F-IMPT (p < 0.001). In addition, it was confirmed that the integral whole body dose can be dramatically reduced in IMPT plans compared with VMAT plans. Both of 2F-IMPT and 3F-IMPT could effectively reduce spinal cord dose, as well as low integral whole body dose to a certain extent, while maintaining similar target coverage compared to VMAT. IMPT could be a promising treatment technique for patients with cervical esophageal cancer.

Comparison between flattening filter-free (FFF) and flattened photon beam VMAT plans for the whole brain radiotherapy (WBRT) with hippocampus sparing

Purpose

To evaluate and investigate the feasibility of flattening filter‐free (FFF) beam for the whole‐brain radiotherapy (WBRT) with hippocampus sparing.

Methods

Eighteen patients with volumetric‐modulated arc therapy (VMAT) plans in FFF and conventional beam modes were included in this study. The prescribed dose was 30 Gy in 10 fractions. The conformity index (CI), heterogeneity index reported by TPS (HI‐M), and homogeneity index (HI) for planning target volume (PTV) were evaluated. Subsequently, the following parameters for PTV were calculated and compared: D_2%, D_98%; the mean dose, maximum dose, and minimal dose for OARs. Plan modulation index, total MUs, and the gamma index were used to evaluate the plan quality.

Results

HI‐M results were similar for the two techniques (1.239 vs. 1.247, respectively, p = 0.048); FFF beam plans yielded lower D2% compared to FF beam plans (3,416.3 cGy vs. 3,437.2 cGy, p = 0.22), mean dose (3,177.5 cGy vs. 3,195.2 cGy, p = 0.009), and CI (0.884 vs. 0.876, p = 0.001) for PTV. Significant differences were observed between the two beam modes (FF model vs. FFF model) for the maximum dose (1,612.9 cGy vs. 1,470.2 cGy, respectively, p < 0.001), minimum dose (987.6 cGy vs. 898.8 cGy, respectively, p < 0.001), and the mean dose (1144.4 cGy vs. 1047.3 cGy, respectively, p < 0.001) to the hippocampus, and the maximum dose to the eyes (2,792.6 cGy vs. 2,751.3 cGy, respectively, p < 0.001). The average total MUs for FFF‐VMAT plans was significantly greater than FF‐VMAT plans. However, differences for the plan modulation index and the gamma index were negligible.

Conclusion

In comparison with FF beam, the FFF beam mode offers a clear benefit with respect to WBRT with hippocampal sparing.

Endoscopic Submucosal Dissection for Superficial Proximal Esophageal Neoplasia is Highly Successful

OBJECTIVE

The aim of this study was to evaluate the outcomes of endoscopic submucosal dissection (ESD) for superficial proximal esophageal neoplasia.

SUMMARY OF BACKGROUND DATA

The surgery for a tumor located in proximal esophagus is relatively difficult and leads to a high morbidity and mortality. ESD is a minimally invasive endoscopic treatment of superficial neoplasia of the gastrointestinal tract allowing en block resection with low recurrence rates; however, ESD for superficial proximal esophageal neoplasia is little known.

METHODS

We retrospectively analyzed 102 consecutive patients who fit the inclusion criteria with 106 lesions who underwent ESD from February 2009 to July 2015 at the Zhongshan Hospital, Fudan University in Shanghai, China. During the study, the en bloc and pathologically complete resection rates, complication rate, incidence of esophageal stricture after ESD, disease-specific, and overall survival rates were evaluated.

RESULTS

The mean age was 62 (45-84) years with 100% en bloc resection rate. The mean operation time was 48 (10-144) minutes. The mean diameter of the resected tumors was 2.9 (1.2-6.5) cm. The pathological diagnoses were high-grade intraepithelial dysplasia in 45 (42.5%) lesions, and the rest were squamous cell carcinoma with staging of intraepithelial in 18 (17.0%), lamina propria in 13 (12.3%), muscularis mucosa in 16 (15.1%), SM1 in 10 (9.4%), and SM2 or deeper in 4 (3.8%) of the lesions. The R0 resection rates were 94.3% (100/106). There was no delayed bleeding. Two small perforations observed were closed successfully with clips. Symptomatic esophageal strictures in 17 (16.7%) patients were treated by endoscopic balloon dilation with a mean of 4 (1-14) times and 88.2% (15/17) success. Additional treatments of esophagectomy or chemoradiotherapy were recommended to patients with SM1 or deeper neoplasia or incomplete resection. Local recurrence was observed in 3 (2.9%) cases. Fifteen patients were lost to follow-up. Five-year overall survival rate was 98% and disease-specific survival rate was 100%. The mean follow-up time was 33.6 months.

CONCLUSIONS

ESD for the superficial proximal esophageal neoplasia is a safe and a very effective treatment method with a 100% 5-year disease-specific survival rate.