Stereotactic Body Radiotherapy for Renal Cell Carcinoma: Oncological and Renal Function Outcomes.

AIMS: To evaluate oncological and renal function outcomes of stereotactic body radiotherapy (SBRT) for medically inoperable patients with localised renal cell carcinoma. MATERIALS AND METHODS: Consecutive patients treated with curative intent SBRT (30-45 Gy in five fractions or 42 Gy in three fractions) were included. Data on local control (Response Evaluation Criteria in Solid Tumors [RECIST] v1.1), distant metastasis, impact on estimated glomerular filtration rate (eGFR) and proportional ipsilateral and contralateral renal functions (measured through renal scans) were collected. Univariate and multivariable analyses were conducted to determine association of variables with oncological and renal function outcomes. RESULTS: Seventy-four patients were analysed. The median follow-up was 27.8 months (interquartile range 17.6-41.7). Fifty-seven per cent had tumours ≥ T1b. One-, 2- and 4-year cumulative incidence of local failure was 5.85, 7.77 and 7.77%, respectively. The cumulative incidence of distant metastasis at 2 years was 4.24%. On multivariable analysis, a lower planning target volume (PTV) mean dose (P = 0.019) and a larger PTV (P = 0.005) were significantly associated with the risk of developing local failure. A lower PTV maximum dose (P = 0.039) was significantly associated with the risk of developing distant metastasis. The median change in global eGFR (ml/min) from pre-SBRT levels was -7.0 (interquartile range -14.5 to -1.0) at 1 year and -11.5 (interquartile range -19.5 to -4.0) at 2 years. The proportion of ipsilateral (differential) renal function decreased over time from 47% of overall renal function pre-SBRT to 36% at 2 years, whereas the proportion of contralateral renal function correspondingly improved. On multivariable analysis, a higher volume of uninvolved renal cortex (P < 0.0001) was significantly associated with a smaller decrease in eGFR over time. CONCLUSION: In this large institutional cohort, oncological outcomes of renal cell carcinoma treated with SBRT were favourable and a longitudinal decline in renal function in the ipsilateral kidney and compensatory increase in the contralateral kidney were observed. Clinical and dosimetric factors were significantly associated with oncological and renal function outcomes.

Post-fire redistribution of 137Cs and algal communities in contaminated forest soils in Belarus.

This study was carried out in the forest area of the Gomel region of Belarus contaminated by 137Cs following the Chernobyl accident of 1986. The aim of the study was to explore the effects of different types of wildfires on the biological availability of radionuclides and the distribution of algal communities in fire-affected soils. Soil samples were collected in 2017 and 2018 from sites burnt by surface and crown fires, and from two unburnt reference locations. The soil samples were analyzed for radioactivity, agrochemical characteristics and the abundance of photoautotrophs. The proportions of various 137Cs fractions, according to our findings, differ between fire-affected and unburnt forest soils, and also between the different types of wildfire. The forest soil affected by surface fire is characterized by an increased amount of easily exchangeable and mobile fractions. In the forest burnt by the crown fire, where the above ground vegetation was almost completely destroyed, the mobile fractions of 137Cs are easily washed out from the topsoil, allowing them to penetrate into deeper soil layers. Soil algae play an important ecological role in sustaining terrestrial ecosystems and are sensitive to various physicochemical properties of soil, such as pH level, nutrient content and moisture. Most of these physicochemical properties are known to stimulate the growth of algal cells, however no evidence has been found in this study regarding the relationship between 137Cs activities in soil and the algal species richness.

Prostate-specific Antigen Bounce After Stereotactic Body Radiotherapy for Prostate Cancer: A Pooled Analysis of Four Prospective Trials.

AIMS: We conducted a pooled analysis of four prospective stereotactic body radiotherapy (SBRT) trials of low- and intermediate-risk prostate cancer to evaluate the incidence of prostate-specific antigen (PSA) bounce and its correlation with the time-dose-fraction schedule. The correlation between bounce with PSA response at 4 years (nadir PSA < 0.4 ng/ml) and biochemical failure-free survival (BFFS) was also explored. MATERIALS AND METHODS: The study included four treatment groups: 35 Gy/five fractions once per week (QW) (TG-1; n = 84); 40 Gy/five fractions QW (TG-2; n = 100); 40 Gy/five fractions every other day (TG-3; n = 73); and 26 Gy/two fractions QW (TG-4; n = 30). PSA bounce was defined as a rise in PSA by 0.2 ng/ml (nadir + 0.2) or 2 ng/ml (nadir + 2.0) above nadir followed by a decrease back to nadir. Patients with fewer than three follow-up PSA tests were excluded from the pooled analysis. RESULTS: In total, 287 patients were included, with a median follow-up of 5.0 years. The pooled 5-year cumulative incidence of bounce by nadir + 2.0 was 8%. The 2-year cumulative incidences of PSA bounce by nadir + 0.2 were 28.9, 21, 19.6 and 16.7% (P = 0.12) and by nadir + 2.0 were 7.2, 8, 2.7 and 6.7% (P = 0.32) for TG-1 to TG-4, respectively. Multivariable analysis revealed that for nadir + 2.0, pre-treatment PSA (odds ratio 0.49; 95% confidence interval 0.26-0.97) correlated with PSA bounce. Although PSA bounce by nadir + 0.2 (odds ratio 0.10; 95% confidence interval 0.04-0.24) and nadir + 2.0 (odds ratio 0.29; 95% confidence interval 0.09-0.93) was associated with a lower probability of PSA response at 4 years, there was no association between bounce by nadir + 0.2 (hazard ratio 0.36; 95% confidence interval 0.08-1.74) or nadir + 2 (hazard ratio 1.77; 95% confidence interval 0.28-11.07) with BFFS. CONCLUSION: The incidence of PSA bounce was independent of time-dose-fraction schedule for prostate SBRT. One in 13 patients experienced a bounce high enough to be misinterpreted as biochemical failure, and clinicians should avoid early salvage interventions in these patients. There was no association between PSA bounce and BFFS.

Stereotactic Ablative Body Radiotherapy for Primary Renal Cell Carcinoma in Non-surgical Candidates: Initial Clinical Experience.

AIMS: To report the outcomes of a cohort of patients with renal cell carcinoma (RCC) treated using stereotactic ablative body radiotherapy (SABR). MATERIALS AND METHODS: Patients treated with SABR for primary RCC from 1 January 2012 to 1 April 2015 were retrospectively reviewed. Patients were non-surgical candidates treated with doses ranging from 30 to 40 Gy in five fractions. The tumour sizes and serum creatinine were compared between the pre-treatment assessment and subsequent follow-up assessments. The worst acute and late grade ≥2 toxicity rates were recorded. RESULTS: In total, 16 patients were included in this study. The median follow-up was 19 months (range 7-30). Eleven patients had stable disease, four had partial responses and none had progressive disease, indicating a local control rate of 100%. One patient had grade 2 acute nausea and two patients had grade 4 renal toxicities (two patients with pre-existing stage 4-5 chronic kidney disease required dialysis following SABR). Four of four patients with pre-SABR symptoms (pain and/or haematuria) had symptomatic relief after SABR. CONCLUSION: SABR for RCC is safe, the toxicities are minimal, and the local control is excellent at early follow-up. This technique should be further evaluated in prospective clinical trials.

Sci-Fri PM: Delivery - 03: Spine SBRT: Treating multiple vertebrae using cone-beam CT image-guidance and the hexapod robotic couch.

PURPOSE: The intent of spinal SBRT is to maximize the biological effective dose and improve local control, while sparing the adjacent spinal cord. We report on the spinal SBRT positional accuracy for multiple, consecutive vertebrae in a single course, using the Elekta Synergy-S and BodyFIX immobilization systems. METHODS: After initial patient adjustment, verification cone-beam CT (CBCT) images were acquired before, during and after treatment. These images were used to assess immobilization and correct any misalignment exceeding 1 mm or 1°, in all six degrees-of-freedom using the HexaPOD robotic couch. This analysis is based on 415 verification images from 67 consecutive courses of treatment. These treatment courses comprised 25 single thoracic vertebrae, 16 multiple thoracic vertebrae, 20 single lumbar vertebrae and 6 multiple lumbar vertebrae. RESULTS: The absolute intra-fraction motion averaged over all directions (±std dev.) for the T-single, T-multiple, L-Single and L-Multiple was 0.54 (±0.73) mm, 0.54 (±0.88) mm, 0.36 (±0.57) mm, and 0.47 (±0.63) mm respectively. The percentage that exceeded the 1.5 mm planning margin was 3.8%, 4.0%, 1.0% and 0.85% respectively. T-spine treatments were out-of-tolerance more frequently than the L-spine. There was a statistically significant difference between single and multiple lumbar treatments (unpaired t-test, p<0.01), but this was not clinically significant as 99% were within our 1.5 mm margin. CONCLUSIONS: Near-rigid immobilization with the acquisition of intra-fraction CBCT images and the correction of misalignments in all six degrees-of-freedom provides the necessary precision to safely perform SBRT of consecutive spinal metastases within one course of treatment.

[Transuranium elements on the Belarus territory].

The isotope composition and the dynamics of its change in Chernobyl falling-outs in the Belarus territory are studied. The levels of the content of transuranium elements in the basic components of ecosystems such as air, ground, water, plants and animals are quatified. The features of the inflow of transuranium elements into living organisms are determined.

Poster - Thurs Eve-43: Verification of dose calculation with tissue inhomogeneity using MapCHECK.

MapCHECK (Sun Nuclear, Melbourne, FL) with 445 diode detectors has been used widely for routine IMRT quality assurance (QA)1 . However, routine IMRT QA has not included the verification of inhomogeneity effects. The objective of this study is to use MapCHECK and a phantom to verify dose calculation and IMRT delivery with tissue inhomogeneity. A phantom with tissue inhomogeneities was placed on top of MapCHECK to measure the planar dose for an anterior beam with photon energy 6 MV or 18 MV. The phantom was composed of a 3.5 cm thick block of lung equivalent material and solid water arranged side by side with a 0.5 cm slab of solid water on the top of the phantom. The phantom setup including MapCHECK was CT scanned and imported into Pinnacle 8.0d for dose calculation. Absolute dose distributions were compared with gamma criteria 3% for dose difference and 3 mm for distance-to-agreement. The results are in good agreement between the measured and calculated planar dose with 88% pass rate based on the gamma analysis. The major dose difference was at the lung-water interface. Further investigation will be performed on a custom designed inhomogeneity phantom with inserts of varying densities and effective depth to create various dose gradients at the interface for dose calculation and delivery verification. In conclusion, a phantom with tissue inhomogeneities can be used with MapCHECK for verification of dose calculation and delivery with tissue inhomogeneity.

Effects of water status and soil fertility on the C-isotope signature in Pinus radiata.

The efficiency with which trees use water is a major determinant of growth under water-limited conditions. We investigated whether increased access to water and nutrients alters water-use efficiency in Pinus radiata D. Don. Intrinsic transpiration efficiency, defined here as the ratio of CO(2) assimilated and water transpired at a given vapor pressure deficit, is determined by the difference between ambient atmospheric CO(2) concentration (c(a)) and leaf intercellular CO(2) concentration (c(i)). The mean value of c(i)/c(a) can be inferred from an analysis of carbon isotope discrimination (Delta) in wood samples. A total of 117 trees, growing at sites with widely varying soil and climatic conditions in Australia and New Zealand, were cored and distinct annual rings were analyzed for their carbon isotope ratio, and correlated with rainfall during the July-June growing season in the year in which the wood was grown. Where possible, carbon isotope ratios were compared for different years within the same trees. The c(i)/c(a) ratio decreased with decreasing water availability, suggesting that intrinsic transpiration efficiency increased with decreasing water availability. An increase in growing season rainfall of 900 mm resulted in an increase in Delta of about 2.0 per thousand, corresponding to a decrease in intrinsic transpiration efficiency of approximately 24%. A stronger relationship was obtained when carbon isotope discrimination was expressed as a function of the ratio of rainfall to potential transpiration. Carbon isotope discrimination was also negatively correlated with mean annual vapor pressure deficit at different sites. In contrast, nutrient availability had no significant effect on carbon isotope discrimination.

[Standardization of miral levels in the soil]. / Normirovanie soderzhaniia mirala v pochve.

On the basis of results of studies on experimental substantiation of MAC for miral in soil it has been found out, that the sub-threshold miral amounts according to the water-migrational, air-migrational, translocational and general sanitary indices of harmfulness equal 0.03, 3, 0.03 and 0.15 mg/kg respectively. Therefore, water-migrational and translocational indices are the limiting indices of harmfulness for miral. 0.03 mg per 1 kg of absolutely dry soil is recommended for miral MAC according to the acting substance.

[Substantiation of cyclophos MPEL in the soil]. / Obosnovanie PDK tsiklofosa v pochve.

On the basis of studies aimed at the substantiation of MAC for cyclophos in soil it was established, that subthreshold amounts of cyclophos according to the water-migration and air-migration indexes of harmfulness equal 0.03 mg per 1 kg of absolutely dry soil, according to the general sanitary index--0.1 mg/kg. Since cyclophos destruction period in plants is relatively short (8 days), there is no danger of translocation of the pesticide from soil in amounts exceeding the maximum allowable level for cyclophos in food stuffs. The pesticide migration in the system soil-plant was not determined. The water migration and air-migration indexes are the limiting indexes of harmfulness for cyclophos. 0.03 mg/kg is recommended as the maximum allowable concentration of cyclophos in soil.