Volumetric-modulated arc therapy vs conventional fixed-field intensity-modulated radiotherapy in a whole-ventricular irradiation: a planning comparison study

Preoperative chemoradiotherapy for locally advanced low rectal cancer using intensity-modulated radiotherapy to spare the intestines: a single-institutional pilot trial

The irradiated volume of intestines is associated with gastrointestinal toxicity in preoperative chemoradiotherapy for rectal cancer. The current trial prospectively explored how much of the irradiated volume of intestines was reduced by intensity-modulated radiotherapy (IMRT) compared with 3-dimensional conformal radiotherapy (3DCRT) and whether IMRT might alleviate the acute gastrointestinal toxicity in this population. The treatment protocol encompassed preoperative chemoradiotherapy using IMRT plus surgery for patients with clinical T3-4, N0-2 low rectal cancer. IMRT delivered 45 Gy per 25 fractions for gross tumors, mesorectal and lateral lymph nodal regions, and tried to reduce the volume of intestines receiving 15 Gy (V15 Gy) < 120 cc and V45 Gy ≤ 0 cc, respectively, while keeping target coverage. S-1 and irinotecan were concurrently administered. Acute gastrointestinal toxicity, rates of clinical downstaging, sphincter preservation, local regional control (LRC) and overall survival (OS) were evaluated. Twelve enrolled patients completed the chemoradiotherapy protocol. The volumes of intestines receiving medium to high doses were reduced by the current IMRT protocol compared to 3DCRT; however, the predefined constraint of V15 Gy was met only in three patients. The rate of ≥ grade 2 gastrointestinal toxicity excluding anorectal symptoms was 17%. The rates of clinical downstaging, sphincter preservation, three-year LRC and OS were 75%, 92%, 92% and 92%, respectively. In conclusion, preoperative chemoradiotherapy using IMRT for this population might alleviate acute gastrointestinal toxicity, achieving high LRC and sphincter preservation; although further advancement is required to reduce the irradiated volume of intestines, especially those receiving low doses.

Neoadjuvant Chemotherapy and Whole Ventricular Irradiation for Pure Intracranial Germinoma: A Comparison of Three Brain-Sparing Techniques

Objective To quantitate and compare the dosimetric properties of three brain-sparing radiation therapy techniques for pure intracranial germinomas with dose-volume analysis of target and normal brain structures. Methods We identified 18 patients with central nervous system (CNS) germinoma who had achieved local control and had excellent neurocognitive outcomes. Four patients who were treated with a simultaneous integrated boost (SIB) plan of 22.5Gy to whole ventricle (WV) and 30Gy to primary were re-planned with 24Gy to WV-only and the Children's Oncology Group (COG) protocol of 18Gy to WV with a sequential boost to 30Gy. Organ-at-risk (OAR) doses for hippocampi, temporal lobes, whole brain, whole brain minus whole ventricles planning target volume (WB-WVPTV), WVPTV, and boost volume were comparatively studied. Results For patients treated with the SIB plan, an excellent neurocognitive function has previously been shown to be well preserved. Three-year event-free survival (EFS) and overall survival (OS) for this group have also previously been demonstrated (89.5% and 100%, respectively). Mean and integral OAR doses were comparable between SIB and WV-only plans but were lower for COG plans. Whole brain, whole brain minus WVPTV, and temporal lobe V20, V18, and V12, as well as hippocampi V20, V25, and V30, were comparable between SIB and WV-only plans but were lower for the COG plans. Conclusion Compared to the WV-only method, the SIB plan permits more dose to the primary site by 6 Gy without compromising neurocognitive control. While maintaining the 30Gy boost, the COG protocol reduces the WVPTV dose to 18Gy. It remains to be seen whether WV dose reduction risks reducing local control.

Radiation Dose-escalated Chemoradiotherapy Using Simultaneous Integrated Boost Intensity-Modulated Radiotherapy for Locally Advanced Unresectable Thoracic Oesophageal Squamous Cell Carcinoma: A Single-institution Phase I Study

AIMS

About 80% of cases of locally advanced unresectable thoracic oesophageal squamous cell carcinoma recur within the irradiation fields after chemoradiotherapy. Radiation dose escalation using advanced radiotherapy techniques is expected to improve clinical outcomes by reducing local and regional recurrence. The current study aimed to determine the recommended escalated radiation dose for these patients.

MATERIALS AND METHODS

Patients with locally advanced unresectable thoracic oesophageal squamous cell carcinoma with good performance status underwent chemoradiotherapy using simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) with elective nodal irradiation. SIB-IMRT was delivered in five fractions per week. The radiation dose to the unresectable gross tumour was escalated from 66 Gy to a planned maximum dose of 72 Gy in 3 Gy increments in a standard 3 + 3 design. The doses to the resectable component, superficial tumours and elective nodal regions were fixed as 60, 51 and 48 Gy, respectively. Cisplatin and 5-fluorouracil were concurrently administered. Dose-limiting toxicity (DLT) was defined as acute grade 3 oesophagitis, grade 2 pneumonitis, grade 2 cardiac toxicity and a failure to complete planned radiotherapy within 60 days. Locoregional control and overall survival were estimated using the Kaplan-Meier method. Nine patients were enrolled.

RESULTS

DLTs occurred in one of six and two of three patients at doses of 66 and 69 Gy, respectively. All DLTs were grade 3 oesophagitis. The recommended dose was determined as 66 Gy delivered in 30 fractions based on the predefined criteria. With a median follow-up period of 23 months, the 1-year locoregional control and overall survival rates were 67 (95% confidence interval = 19-90) and 78% (95% confidence interval = 36-94), respectively.

CONCLUSION

The recommended radiation dose in chemoradiotherapy using SIB-IMRT with elective nodal irradiation was 66 Gy delivered in 30 fractions.

Selection criteria for 3D conformal radiotherapy versus volumetric-modulated arc therapy in high-grade glioma based on normal tissue complication probability of brain

There are no quantitative selection criteria for identifying high-grade glioma (HGG) patients who are suited for volumetric-modulated arc therapy (VMAT). This study aimed to develop selection criteria that can be used for the selection of the optimal treatment modality in HGG. We analyzed 20 patients with HGG treated by 3D conformal radiotherapy (3DCRT). First, VMAT plans were created for each patient retrospectively. For each plan, the normal tissue complication probability (NTCP) for normal brain was calculated. We then divided the patients based on the NTCPs of the 3DCRT plans for normal brain, using the threshold of 5%. We compared the NTCPs of the two plans and the gross tumor volumes (GTVs) of the two groups. For the GTVs, we used receiver operating characteristic curves to identify the cut-off value for predicting NTCP < 5%. We determined the respective correlations between the GTV and the GTV's largest cross-sectional diameter and largest cross-sectional area. In the NTCP ≥ 5% group, the NTCPs for the VMAT plans were significantly lower than those for the 3DCRT plans (P = 0.0011). The NTCP ≥ 5% group's GTV was significantly larger than that of the NTCP < 5% group (P = 0.0016), and the cut-off value of the GTV was 130.5 cm3. The GTV was strongly correlated with the GTV's largest cross-sectional diameter (R2 = 0.82) and largest cross-sectional area (R2 = 0.94), which produced the cut-off values of 7.5 cm and 41 cm2, respectively. It was concluded that VMAT is more appropriate than 3DCRT in cases in which the GTV is ≥130.5 cm3.