Comparison of Tumor Control between FLASH and CONV in an Orthotopic Breast Cancer Model

PURPOSE/OBJECTIVE(S)

Post-lumpectomy radiotherapy (RT) reduces in-breast tumor recurrence by eradicating residual, occult breast cancer (BC) that may be in the mm size scale. The ability of FLASH-RT to eradicate BC relative to conventional dose rate (CONV) RT is unknown. ∼ 20Gy RT is currently used clinically for single-fraction breast IORT. Determine the effectiveness of FLASH compared to CONV in eradicating small tumors in an orthotopic, syngeneic model of BC using single-fraction 20 or 30Gy RT.

MATERIALS/METHODS

Radiation sensitive, mammary tumor cell line Py117 from the transgenic model of the mouse mammary tumor virus promoter driving the polyoma middle T antigen (MMTV- PyMT) efficiently forms non-metastatic, orthotopic tumors in C57BL/6 mice. 106 Py117 cells were injected orthotopically into the left 4th mammary fat pad of C57Bl/6J mice. Radiotherapy was performed with a custom jig that allows for fixed positioning of the target volume (2x2cm radiation field) with 5mm of margin into surrounding tissue. Tumors were irradiated at ∼30mm3 volume or, for comparison, at a range of greater volumes (200-800mm3) with 20 or 30Gy FLASH or CONV with 16-17 MeV electrons.

RESULTS

Small 30mm3 tumors regressed until ∼ day 15 after 20Gy single fraction RT then regrew for both FLASH and CONV. 30mm3 tumors were eradicated with both FLASH and CONV at 30Gy with no regrowth up to day 35 post-RT. Larger tumors irradiated with 30Gy regressed until ∼ day 12 post-RT then regrew for both FLASH and CONV. There was no significant difference in growth delay or tumor eradication between FLASH and CONV in any cohort.

CONCLUSION

FLASH was as effective as CONV in controlling growth and eradicating murine BC. Based on other preclinical studies, single-fraction doses between 20 and 30Gy, as well as hypofractioned RT schedules, may identify FLASH doses that achieve comparable tumor control with less toxicity than CONV. Such findings would encourage clinical trials of FLASH in human BC.

Metformin versus insulin therapy for gestational diabetes: Effects on offspring anthropometrics and metabolism at the age of 9 years: A follow-up study of two open-label, randomized controlled trials

AIMS

To compare anthropometrics, and lipid and glucose metabolism in the 9-year-old offspring of mothers treated with metformin or insulin for gestational diabetes mellitus (GDM).

MATERIALS AND METHODS

This was a Finnish two-centre, 9-year follow-up study of two open-label, randomized controlled trials comparing the effects observed in the offspring of mothers who received metformin and insulin treatment for GDM. Measurements included anthropometrics, blood pressure, lipoproteins, and oral glucose tolerance tests. This study was registered with ClinicalTrials.gov, number NCT02417090.

RESULTS

At the age of 9 years 172 children (55% of the original study cohort, 82 from the metformin and 90 from the insulin group) participated in the study. No differences were found between the 9-year-old offspring groups in anthropometric variables, including body mass index and waist-to-height ratio. The offspring in the metformin group had higher high-density lipoprotein (HDL) cholesterol concentrations (1.72 vs. 1.54 mmol/L; P = 0.039) but lower low-density lipoprotein cholesterol (2.39 vs. 2.58 mmol/L; P = 0.046) and apolipoprotein B concentrations (0.63 vs. 0.67 g/L; P = 0.043) than the offspring in the insulin group. The difference in HDL cholesterol concentration was found to be significant only in boys (P = 0.003). The 2-hour glucose value in the oral glucose tolerance test was 0.6-mmol/L lower in boys from the metformin group than in those from the insulin group (P = 0.015).

CONCLUSIONS

Metformin treatment for GDM is associated with similar offspring growth and glucose metabolism but a more favourable lipid profile at the age of 9 years as compared to insulin treatment.

Exploring diastolic pressure ratio to fractional flow reserve discordance and a hypothesis on tailoring diastolic pressure ratio cut-off values to improve diagnostic accuracy in the mid- and distal-LAD

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This study assessed diastolic pressure ratio to FFR discordance.

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12.7% of LAD lesions in this study had discordant result.

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2.4% of non-LAD lesions had discordant results.

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This represents a statistically significant difference in discordance rate.

Previous studies have identified a higher rate of discordance between non-hyperaemic pressure ratios and FFR in the LAD when compared to the other two coronary arteries. We hypothesised that in keeping with recently published data, we would identify a higher discordance rate between diastolic pressure ratio (DPR) and FFR in the LAD compared to the RCA or LCx. In our study, 12.7% of LAD lesions had discordant results compared with 2.4% of non-LAD lesions. This represents a statistically significant increased rate of discordance in LAD lesions compared to non-LAD lesions (p = 0.04986). Note was made of a tendency for non-proximal LAD lesions to be associated with false-positive DPR results in the borderline range (0.88 and 0.89). In a speculative, hypothesis generating post-hoc analysis, we found an improved diagnostic accuracy of DPR when the cut-off value for a positive DPR in the non-proximal LAD was changed to ≤0.87. It is fathomable that improvements in the diagnostic accuracy of DPR for FFR may be improved by tailoring DPR cut-offs to the location of the lesion assessed.

P919 The correlation between cardiac biomarkers and findings on transthoracic echocardiography in the intensive care unit

BACKGROUND

Trans-thoracic echo (TTE) is a commonly performed non-invasive investigation for the cardiovascular assessment of critically ill patients in the Intensive Care Unit (ICU). Raised cardiac biomarkers are commonly cited as an indication for TTE, however the significance of these biomarker elevations in the critical care setting is unclear.

PURPOSE

The aim of this study was to describe findings on TTE in an Irish ICU cohort and to determine if there was any correlation between these findings and serum N-terminal pro b-type natiuretic (NT-proBNP) and high sensitivity troponin T (HsTnT) levels.

METHODS

Patients admitted to the ICU and who received a TTE between January 2018 and February 2019 were identified. Based on TTE findings, patients were divided into two groups: ‘Normal group’ and ‘Abnormal group’. For the purpose of this study, minor abnormalities including concentric left ventricular hypertrophy, diastolic dysfunction and hyper-dynamic left ventricular function were included in the Normal group. The Abnormal group included reductions in LV function, regional wall motion abnormalities and significant valvular heart disease. Continuous variables were expressed as medians and interquartile range. The groups were compared using the z-test for continuous variables and fishers exact test for categorical variables, with a p value of < 0.05 considered significant.

RESULTS

There were 358 patients admitted to the ICU during the study period. The mean age was 59.8 ± 17 years and over half of the patients (55%) were male. One hundred and fifteen patients (32%) had a reported TTE, of which 55% were normal and 22% had minor abnormalities (Normal group). The remaining 23% showed significant abnormalities (Abnormal group).

The prevalence of a NT-proBNP result over 4 times the upper limit of normal (>4xULN) was not significantly different between groups (67% in Normal group vs 71% in Abnormal group, Fisher exact test statistic value is 0.7887, p < .05). However a HsTnT value >4xULN was more common in the Abnormal group than the Normal group (73% vs 46%, Fisher exact test statistic value is 0.0231, p < .05). Similarly, Median NT-proBNP did not differ significantly between the groups; (2254pg/mL; IQR: 11,758 in the Normal group vs 6428pg/mL; IQR: 5,789 in the Abnormal group, p = 0.52218) but Median HsTnT level was significantly higher in the Abnormal group than Normal group; (123ng/L ; IQR: 656 vs 51ng/L; IQR: 163.5 ,p = 0.0278).

CONCLUSION

TTE is performed commonly in the ICU, with one-third of ICU admissions receiving a TTE. Over 75% were reported as normal or showing only minor abnormalities. NT-Pro BNP was commonly significantly elevated but did not correlate with the subsequent diagnostic yield of significant abnormalities on echocardiography. HsTnT levels were more commonly significantly raised in patients with abnormal TTE results and the role of troponin in this setting requires further evaluation.

Determination of Low-Level Pesticide Residues in Soft Drinks and Sports Drinks by Liquid Chromatography with Tandem Mass Spectrometry: Collaborative Study

A collaborative study was conducted on a method for the measurement of 11 low-level pesticide residues in soft drinks and sports drinks by liquid chromatography with tandem mass spectrometry. The pesticide residues determined in this study were alachlor, atrazine, butachlor, isoproturon, malaoxon, monocrotophos, methyl paraoxon, phorate, phorate sulfone, phorate sulfoxide, and 2,4-dichlorophenoxyacetic acid (2,4-D). Blind fortification solutions containing 3 different levels of pesticide residues were provided to 9 collaborating laboratories to create test samples at concentrations of 0, 0.1, and 0.5 g/L with a 10-fold concentration for phorate in a total of 6 matrixes (2 colas, 1 diet cola, 1 clear lemon-lime soft drink, 1 orange soft drink, and 1 sports drink). Good qualitative performance of the method was demonstrated for all pesticide residues. Reproducibility relative standard deviation (RSDR) ranged from 7 to 151 for alachlor, atrazine, butachlor, isoproturon, malaoxon, monocrotophos, methyl paraoxon, phorate, phorate sulfone, phorate sulfoxide, and 2,4-D at the 0.1 g/L level (1.0 g/L for phorate). At 0.5 g/L (5.0 g/L for phorate), RSDR ranged from 9 to 57 for alachlor, atrazine, butachlor isoproturon, malaoxon, monocrotophos, methyl paraoxon, phorate, phorate sulfone, phorate sulfoxide, and 2,4-D in all matrixes. Repeatability relative standard deviation (RSDr), applicable to the diet cola and sports drink, ranged from 0 to 124 for the 11 pesticide residues at the 0.1 g/L level (1.0 g/L for phorate). At 0.5 g/L (5.0 g/L for phorate), RSDr ranged from 4 to 26. Recoveries for the 11 pesticide residues in all matrixes ranged from 84 to 300 at the 0.1 g/L level (1.0 g/L for phorate) and from 66 to 127 at the 0.5 g/L (5.0 g/L for phorate) level. Coefficients of determination (r2) of the matrix-matched calibration curves were 0.95. It is recommended that the method be accepted by AOAC as Official First Action with a limit of quantification of 0.5 g/L for alachlor, atrazine, butachlor, isoproturon, malaoxon, methyl paraoxon, monocrotophos, phorate sulfone, phorate sulfoxide, and 2,4-D and 5.0 g/L for phorate.

Determination of Pesticide Residues (>0.5 g/L) in Soft Drinks and Sports Drinks by Gas Chromatography with Mass Spectrometry: Collaborative Study

A collaborative study was conducted on a method for the measurement of 19 low-level pesticide residues in soft drinks and sports drinks by gas chromatography with mass spectrometry (GC/MS). The pesticide residues determined were 2,4-dichlorodiphenyldichloroethylene (2,4-DDE); 2,4-dichlorodiphenyldichloroethane (2,4-DDD); 4,4-dichlorodiphenyldichloroethylene (4,4-DDE); 2,4-dichlorodiphenyltrichloroethane (2,4-DDT); 4,4-dichlorodiphenyltrichloroethane (4,4-DDT); 4,4-dichlorodiphenyldichloroethane (4,4-DDD); -endosulfan; endosulfan-sulfate; dieldrin; aldrin; ethion; chlorpyrifos; -endosulfan; malathion; methyl-parathion; -hexachlorocyclohexane (-HCH); -HCH; -HCH; and -HCH. Blind fortification solutions containing 4 different levels of pesticide residues (0, 0.1, 0.5, and 1.0 g/L) were provided to 8 collaborating laboratories who used them to create test samples in 6 matrixes (also provided): 2 colas, a diet cola, a clear lemon-lime soft drink, an orange soft drink, and a sports drink. Reproducibility (RSDR) for all 19 pesticide residues in all matrixes ranged from 7 to 151 at the 0.1 g/L level, 11 to 121 at 0.5 g/L, and 14 to 67 at 1.0 g/L. Repeatability (RSDr), applicable to the diet cola and the sports drink, ranged from 1 to 76 for the 19 pesticide residues at the 0.1 g/L level, 9 to 38 at 0.5 g/L, and 9 to 38 at 1.0 g/L. Recoveries for the 19 pesticide residues in allmatrixes ranged from 77 to 645 at the 0.1 g/L level, 60 to 231 at 0.5 g/L, and 61 to 146 at 1.0 g/L. It is recommended that the method be accepted by AOAC as Official First Action with a limit of quantification (LOQ) equal to 0.5 g/L for 4,4-DDT; 2,4-DDT; 2,4-DDD; 4,4-DDE; 4,4-DDD; 2,4-DDE; aldrin; dieldrin; -endosulfan; endosulfan-sulfate; chlorpyrifos; and ethion, and an LOQ equal to 1.0 g/L for -endosulfan; -HCH; -HCH; -HCH; -HCH; methyl-parathion; and malathion.