Concordance Rate between Clinicians and Watson for Oncology among Patients with Advanced Gastric Cancer: Early, Real-World Experience in Korea.

Backgrounds/Aims: Watson for Oncology (WFO) is a cognitive technology that processes medical information by analyzing the latest evidence and guidelines. However, studies of the concordance rate between WFO and clinicians for advanced gastric cancer (AGC) are lacking. Methods: We retrospectively reviewed 65 patients with AGC who consulted WFO and the Gachon Gil Medical Center multidisciplinary team (GMDT) in 2016 and 2017. The recommendations of WFO were compared with the opinions of the GMDT. WFO provided three treatment options: recommended (first treatment option), for consideration (second treatment option), and not recommended. Results: In total, 65 patients (mean age 61.0 years; 44 males and 21 females) were included in the study. The concordance rate between WFO and the GMDT was 41.5% (27/65) at the recommended level and 87.7% (57/65) at the for consideration level. The main causes of discordance between WFO and the GMDT were as follows. First, WFO did not consider the medical history. Second, WFO recommended the use of agents that are considered outdated in Korea. Third, some patients wanted to be involved in a clinical trial. Fourth, some patients refused to use the biologic agents recommended by WFO for financial reasons as they were not covered by medical insurance. Conclusions: The concordance rate at the recommended level was relatively low but was higher at the for consideration level. Discordances arose mainly from the different medical circumstances at the Gachon Gil Medical Center (GMC) and the Memorial Sloan Kettering Cancer Center (MSKCC), the main WFO consulting center. The utility of WFO as a tool for supporting clinical decision making could be further improved by incorporating regional guidelines.

Clinical applicability of biologically effective dose calculation for spinal cord in fractionated spine stereotactic body radiation therapy.

BACKGROUND: The aim of the study was to investigate whether biologically effective dose (BED) based on linear-quadratic model can be used to estimate spinal cord tolerance dose in spine stereotactic body radiation therapy (SBRT) delivered in 4 or more fractions. PATIENTS AND METHODS: Sixty-three metastatic spinal lesions in 47 patients were retrospectively evaluated. The most frequently prescribed dose was 36 Gy in 4 fractions. In planning, we tried to limit the maximum dose to the spinal cord or cauda equina less than 50% of prescription or 45 Gy2/2. BED was calculated using maximum point dose of spinal cord. RESULTS: Maximum spinal cord dose per fraction ranged from 2.6 to 6.0 Gy (median 4.3 Gy). Except 4 patients with 52.7, 56.4, 62.4, and 67.9 Gy2/2, equivalent total dose in 2-Gy fraction of the patients was not more than 50 Gy2/2 (12.1-67.9, median 32.0). The ratio of maximum spinal cord dose to prescription dose increased up to 82.2% of prescription dose as epidural spinal cord compression grade increased. No patient developed grade 2 or higher radiation-induced spinal cord toxicity during follow-up period of 0.5 to 53.9 months. CONCLUSIONS: In fractionated spine SBRT, BED can be used to estimate spinal cord tolerance dose, provided that the dose per fraction to the spinal cord is moderate, e.g. < 6.0 Gy. It appears that a maximum dose of up to 45-50 Gy2/2 to the spinal cord is tolerable in 4 or more fractionation regimen.

Establishment of linear accelerator-based image guided radiotherapy for orthotopic 4T1 mouse mammary tumor model.

This study was conducted to assess the feasibility of image guided radiotherapy (IGRT) for orthotopic 4T1 mouse mammary tumor using linear accelerator (LINAC). Eighteen Balb/C mice were inoculated with 4T1 cells on left mammary fat pad and nine of them were irradiated using LINAC. Tumors, planning target volumes (PTV), bowels adjacent to tumors, bones and lungs were delineated on planning CT images. IGRT plans were generated to irradiate prescription dose to at least 90% of the PTV and then compared with conventional 2-dimensional plans with anterior-posterior and posterior-anterior beams with 5 mm margins (2D AP/PA plan). Homemade dose-build-up-cradle was designed to encompass mouse bed for homogeneous dose build up. To confirm the irradiated dose, tumor doses were measured using diode detector placed on the surface of tumors. Plan comparison demonstrated equivalent doses to PTV while sparing more doses to normal tissues including bowel (from 90.9% to 40.5%, median value of mean doses) and bone marrow (from 12.9% to 4.7%, median value of mean doses) than 2D AP/PA plan. Quality assurance using diode detector confirmed that IGRT could deliver 95.3-105.3% of the planned doses to PTV. Tumors grew 505.2-1185.8% (mean 873.3%) in the control group and 436.1-771.8% (mean 615.5%) in the irradiated group. These results demonstrate that LINAC-based IGRT provides a reliable approach with accurate dose delivery in the radiobiological study for orthotropic tumor model maintaining tumor microenvironment.

Clinical application of RapidArc volumetric modulated arc therapy as a component in whole brain radiation therapy for poor prognostic, four or more multiple brain metastases.

PURPOSE: To determine feasibility of RapidArc in sequential or simultaneous integrated tumor boost in whole brain radiation therapy (WBRT) for poor prognostic patients with four or more brain metastases. MATERIALS AND METHODS: Nine patients with multiple (≥4) brain metastases were analyzed. Three patients were classified as class II in recursive partitioning analysis and 6 were class III. The class III patients presented with hemiparesis, cognitive deficit, or apraxia. The ratio of tumor to whole brain volume was 0.8-7.9%. Six patients received 2-dimensional bilateral WBRT, (30 Gy/10-12 fractions), followed by sequential RapidArc tumor boost (15-30 Gy/4-10 fractions). Three patients received RapidArc WBRT with simultaneous integrated boost to tumors (48-50 Gy) in 10-20 fractions. RESULTS: The median biologically effective dose to metastatic tumors was 68.1 Gy(10) and 67.2 Gy(10) and the median brain volume irradiated more than 100 Gy(3) were 1.9% (24 cm(3)) and 0.8% (13 cm(3)) for each group. With less than 3 minutes of treatment time, RapidArc was easily applied to the patients with poor performance status. The follow-up period was 0.3-16.5 months. Tumor responses among the 6 patients who underwent follow-up magnetic resonance imaging were partial and stable in 3 and 3, respectively. Overall survival at 6 and 12 months were 66.7% and 41.7%, respectively. The local progression-free survival at 6 and 12 months were 100% and 62.5%, respectively. CONCLUSION: RapidArc as a component in whole brain radiation therapy for poor prognostic, multiple brain metastases is an effective and safe modality with easy application.