Twenty-two years later: consistent dose estimation of an accidental overexposure by retrospective biological dosimetry

The goal of this study was to retrospectively estimate the exposure dose of a victim from the Lilo radiological accident in Georgia after 22 y and compare it with the original cytogenetics-based analysis performed in our laboratory. Similar types of studies have been published, notably involving victims of the Chernobyl, Goiânia and Tammiku accidents. Nevertheless, their estimations were done after shorter periods of time post-exposure, and in some cases, the exposure might not have been exclusively of an external nature. In this study, Fluorescence In Situ Hybridization (FISH) was used to score chromosomal translocations in lymphocytes from a recent blood sample of the victim and the dose assessment was performed using our laboratory's FISH calibration curve. The resulting whole-body exposure dose of 0.35 Gy [0.12, 0.72] was similar to the one obtained when reanalysing the original scoring data from 1997 (0.38 Gy [0.13-0.75]), suggesting that our current calibration curve could be used for relative dose estimations long time after external exposure.

Colon sparing resection versus extended colectomy for left-sided obstructing colon cancer with caecal ischaemia or perforation: a nationwide study from the French Surgical Association

AIM

It is not known whether patients with obstructive left colon cancer (OLCC) with caecal ischaemia or diastatic perforation (defined as a blowout of the caecal wall related to colonic overdistension) should undergo a (sub)total colectomy (STC) or an ileo-caecal resection with double-barrelled ileo-colostomy. We aimed to compare the results of these two strategies.

METHOD

From 2000 to 2015, 1220 patients with OLCC underwent surgery by clinicians who were members of the French Surgical Association. Of these cases, 201 (16%) were found to have caecal ischaemia or diastatic perforation intra-operatively: 174 patients (87%) underwent a STC (extended colectomy group) and 27 (13%) an ileo-caecal resection with double-end stoma (colon-sparing group). Outcomes were compared retrospectively.

RESULTS

In the extended colectomy group, 95 patients (55%) had primary anastomosis and 79 (45%) had a STC with an end ileostomy. In the colon-sparing group, 10 patients (37%) had simultaneous resection of their primary tumour with segmental colectomy and an anastomosis which was protected by a double-barrelled ileo-colostomy. The demographic data for the two groups were comparable. Median operative time was longer in the STC group (P = 0.0044). There was a decrease in postoperative mortality (7% vs 12%, P = 0.75) and overall morbidity (56% vs 67%, P = 0.37) including surgical (30% vs 40%, P = 0.29) and severe complications (17% vs 27%, P = 0.29) in the colon-sparing group, although these differences did not reach statistical significance. Cumulative morbidity included all surgical stages and the rate of permanent stoma was 66% and 37%, respectively, with no significant difference between the two groups. Overall survival and disease-free survival were similar between the two groups.

CONCLUSION

The colon-sparing strategy may represent a valid and safe alternative to STC in OLCC patients with caecal ischaemia or diastatic perforation.

Thirty-day mortality after emergency surgery for obstructing colon cancer: survey and dedicated score from the French Surgical Association

AIM

The aim was to define risk factors for postoperative mortality in patients undergoing emergency surgery for obstructing colon cancer (OCC) and to propose a dedicated score.

METHOD

From 2000 to 2015, 2325 patients were treated for OCC in French surgical centres by members of the French National Surgical Association. A multivariate analysis was performed for variables with P value ≤ 0.20 in the univariate analysis for 30-day mortality. Predictive performance was assessed by the area under the receiver operating characteristic curve.

RESULTS

A total of 1983 patients were included. Thirty-day postoperative mortality was 7%. Multivariate analysis found five significant independent risk factors: age ≥ 75 (P = 0.013), American Society of Anesthesiologists (ASA) score ≥ III (P = 0.027), pulmonary comorbidity (P = 0.0002), right-sided cancer (P = 0.047) and haemodynamic failure (P < 0.0001). The odds ratio for risk of postoperative death was 3.42 with one factor, 5.80 with two factors, 15.73 with three factors, 29.23 with four factors and 77.25 with five factors. The discriminating capacity in predicting 30-day postoperative mortality was 0.80.

CONCLUSION

Thirty-day postoperative mortality after emergency surgery for OCC is correlated with age, ASA score, pulmonary comorbidity, site of tumour and haemodynamic failure, with a specific score ranging from 0 to 5.

Risk score to predict biliary leakage after elective liver resection

Background

Biliary leakage remains a major cause of morbidity after liver resection. Previous prognostic studies of posthepatectomy biliary leakage (PHBL) lacked power, population homogeneity, and model validation. The present study aimed to develop a risk score for predicting severe PHBL.

Methods

In this multicentre observational study, patients who underwent liver resection without hepaticojejunostomy in one of nine tertiary centres between 2012 and 2015 were randomly assigned to a development or validation cohort in a 2 : 1 ratio. A model predicting severe PHBL (International Study Group of Liver Surgery grade B/C) was developed and further validated.

Results

A total of 2218 procedures were included. PHBL of any severity and severe PHBL occurred in 141 (6·4 per cent) and 92 (4·1 per cent) patients respectively. In the development cohort (1475 patients), multivariable analysis identified blood loss of at least 500 ml, liver remnant ischaemia time 45 min or more, anatomical resection including segment VIII, transection along the right aspect of the left intersectional plane, and associating liver partition and portal vein ligation for staged hepatectomy as predictors of severe PHBL. A risk score (ranging from 0 to 5) was built using the development cohort (area under the receiver operating characteristic curve (AUROC) 0·79, 95 per cent c.i. 0·74 to 0·85) and tested successfully in the validation cohort (AUROC 0·70, 0·60 to 0·80). A score of at least 3 predicted an increase in severe PHBL (19·4 versus 2·6 per cent in the development cohort, P &lt; 0·001; 15 versus 3·1 per cent in the validation cohort, P &lt; 0·001).

Conclusion

The present risk score reliably predicts severe PHBL. It represents a multi-institutionally validated prognostic tool that can be used to identify a subset of patients at high risk of severe PHBL after elective hepatectomy.

Factors influencing recurrence following initial hepatectomy for colorectal liver metastases

BACKGROUND

Data on recurrence patterns following hepatectomy for colorectal liver metastases (CRLMs) and their impact on long-term outcomes are limited in the setting of modern multimodal management. This study sought to characterize the patterns of, factors associated with, and survival impact of recurrence following initial hepatectomy for CRLMs.

METHODS

A retrospective cohort study of patients undergoing initial hepatectomy for CRLMs at 39 institutions (2006-2013) was conducted. Kaplan-Meier methods were used for survival analyses. Overall survival landmark analysis at 12 months after hepatectomy was performed to compare groups based on recurrence. Multivariable Cox and regression models were used to determine factors associated with recurrence.

RESULTS

Among 2320 patients, tumours recurred in 47·4 per cent at median of 10·1 (range 0-88) months; 89·1 per cent of recurrences developed within 3 years. Recurrence was intrahepatic in 46·2 per cent, extrahepatic in 31·8 per cent and combined intra/extrahepatic in 22·0 per cent. The 5-year overall survival rate decreased from 74·3 (95 per cent c.i. 72·2 to 76·4) per cent without recurrence to 57·5 (55·0 to 60·0) per cent with recurrence (adjusted hazard ratio (HR) 3·08, 95 per cent c.i. 2·31 to 4·09). After adjusting for clinicopathological variables, prehepatectomy factors associated with increased risk of recurrence were node-positive primary tumour (HR 1·27, 1·09 to 1·49), more than three liver metastases (HR 1·27, 1·06 to 1·52) and largest metastasis greater than 4 cm (HR 1·19; 1·01 to 1·43).

CONCLUSION

Recurrence after CRLM resection remains common. Although overall survival is inferior with recurrence, excellent survival rates can still be achieved.

Biological dosimetry assessments of a serious radiation accident in Bulgaria in 2011

In 2011, a serious radiation accident occurred in Stamboliyski, Bulgaria, in an industrial sterilisation facility using very-high-activity (60)Co sources. For the five persons accidentally exposed, biological dosimetry based on dicentric analysis was performed in Sofia and in Paris, where the patients were transferred for treatment. Before completing the chromosomal dose assessment, and for the most exposed person, a preliminary cytogenetic evaluation based on electronically transmitted metaphase images was made. The averaged acute whole-body dose estimates for the five patients ranged from 5.2 to 1.2 Gy, and good agreement was obtained between the two laboratories. The patients were also assessed by their prodromal responses and depressed blood cell counts over the first week. The cytogenetic dose estimates were in good accord with those derived from the blood counts, and both techniques indicated that, for the two most seriously exposed persons both techniques indicated that the initial prodromal reactions had suggested somewhat less severe exposure.

Effect of lymphocytes culture variations on the mitotic index and on the dicentric yield following gamma radiation exposure

Fundamentals of biological dosimetry are described in the International Atomic Energy Agency manual, but all over the world each laboratory is using its own protocol. To test the influence of protocol variations, some blood samples were exposed to 0.5 Gy of gamma radiation and mitotic index and dicentric rates were measured under different experimental conditions. The effect of seven parameters [bromodeoxyuridin (BrdU), phytohaemagglutinin and colcemid concentrations, blood and medium volumes, culture duration and incubation temperature] was tested using a Placket and Burman experimental design. The analysis reveals that the mitotic index was influenced by the concentration of BrdU, medium and blood volumes, the culture duration and the temperature. However, none of the factors has a significant impact on the yield of dicentrics. The dicentric assay is robust against reagent variations within the range tested. These results could be used by relevant laboratories as elements of their procedures robustness in any event requiring such demonstration.

Cytogenetic assessment of heterogeneous radiation doses in cancer patients treated with fractionated radiotherapy

The purpose of this study was to evaluate the in vivo dose-response relation of chromosome aberration formation and distribution in a context of localised and fractionated radiotherapy. Cytogenetic analysis was applied to eight patients, all treated for the same tumour localisation; the same localisation was used to prevent the variability usually observed between patients treated with radiotherapy and to allow the corresponding roles of the size of irradiation field and of the dose rate to be studied. The yield of dicentrics, centric rings and fragments was measured in blood samples taken before treatment, during the course of radiotherapy and up to 6 months after. After the first fraction of radiotherapy, we observed that the whole-body dose estimated from the yield of dicentrics and rings was higher (0.35+/-0.2 Gy) than the calculated equivalent whole-body dose (0.07+/-0.04 Gy). By contrast, the partial-body dose derived from the Qdr (quotient of dicentrics and rings) model was estimated to be 2.2+/-0.3 Gy, which agreed quite well with the dose delivered to the tumour (2.1+/-0.1 Gy). We also found a correlation between the yield of induced chromosome aberrations and the target field size (p = 0.014). U-value analysis showed that the distribution of dicentrics and rings was overdispersed, despite the fractionation of the exposure, and a positive correlation between the U-value and the dose rate was observed (p = 0.017). Overall, these results suggest that the proportion of undamaged lymphocytes could increase with the dose rate.

Predictors of long-term survival after liver transplantation for metastatic endocrine tumors: an 85-case French multicentric report

Liver transplantation (LTx) for metastatic endocrine tumors (MET) remains controversial due to the lack of clear selection criteria. From 1989 to 2005, 85 patients underwent LTx for MET. The primary tumor was located in the pancreas or duodenum in 40 cases, digestive tract in 26 and bronchial tree in five. In the remaining 14 cases, primary location was undetermined at the time of LTx. Hepatomegaly (explanted liver > or =120% of estimated standard liver volume) was observed in 53 patients (62%). Extrahepatic resection was performed concomitantly with LTx in 34 patients (40%), including upper abdominal exenteration (UAE) in seven. Postoperative in-hospital mortality was 14%. Overall 5-year survival was 47%. Independent factors of poor prognosis according to multivariate analysis included UAE (relative risk (RR): 3.72), primary tumor in duodenum or pancreas (RR: 2.94) and hepatomegaly (RR: 2.63). After exclusion of cases involving concomitant UAE, the other two factors were combined into a risk model. Five-year survival rate was 12% for the 23 patients presenting both unfavorable prognostic factors versus 68% for the 55 patients presenting one or neither factor (p < 10(-7)). LTx can benefit selected patients with nonresectable MET. Patients presenting duodeno-pancreatic MET in association with hepatomegaly are poor indications for LTx.

International intercomparison for criticality dosimetry: the case of biological dosimetry

The Institute of Radiation Protection and Nuclear Safety (IRSN) organized a biological dosimetry international intercomparison with the purpose of comparing (i) dicentrics yield produced in human lymphocytes; (ii) the gamma and neutron dose estimate according to the corresponding laboratory calibration curve. The experimental reactor SILENE was used with different configurations: bare source 4 Gy, lead shield 1 and 2 Gy and a 60Co source 2 Gy. An increasing variation of dicentric yield per cell was observed between participants when there were more damages in the samples. Doses were derived from the observed dicentric rates according to the dose-effect relationship provided by each laboratory. Differences in dicentric rate values are more important than those in the corresponding dose values. The doses obtained by the participants were found to be in agreement with the given physical dose within 20%. The evaluation of the respective gamma and neutron dose was achieved only by four laboratories, with some small variations among them.

IPM-FISH, a new M-FISH approach using IRS-PCR painting probes: application to the analysis of seven human prostate cell lines

We have developed an alternative multicolor karyotyping technique based on multiplex fluorescence in situ hybridization (M-FISH) and our own optical device with a specific filter set. The most innovative part of our development is the use of interspersed polymerase chain reaction (IRS-PCR) painting probes that show an R-band pattern simultaneous to the combinatorial labeling. This allows us not only to recognize the origin of chromosomal fragments, but to identify the breakpoints as well. We have used this technique to analyze seven cell lines: four prostate cancer cell lines (CA-HPV-10, LNCaP, DU145, and PC3), and three normal transformed epithelial prostate cell lines (PNT1B, PNT2, and PZ-HPV-7). In order to validate our IRS-PCR multiplex FISH (IPM-FISH) technique and to complement the results, we applied comparative genomic hybridization (CGH) and FISH analysis, showing good correlation with the IPM-FISH results. To date, molecular and cytogenetic studies have identified several chromosomal regions that are altered in human prostate cancer; several candidate genes have been suggested. However, reliable markers for predicting the aggressiveness of early prostate cancer are not yet available. Our results show several common, unbalanced rearrangements in the cell lines. These rearrangements are similar to regions already implicated in prostate cancer, validating these cell lines as a good model system.