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The results reported in the literature in the context of an R1 situation for a resected gastric carcinoma are not uniform. An R1 situation worsens the prognosis for the long-term survival of patients. This is significant especially for low T stages and lymph node metastasis with 0-≤3 lymph node metastases. In higher tumor stages with extensive lymph node metastases, the survival difference between R0 and R1 resections is lower and frequently no longer significant. The frequency of R1 resection is approximately 5% (range 1.8-9%) and for adenocarcinoma of the esophagogastric junction (AEG tumors)> 10%. The data are mainly related to the oral and aboral resection line but there are only a few specifications on the circumferential margin. The risk of an infiltrated resection line increases with the size of the tumor (>5 cm), T3+4 and pN2/pN3 stages. Poorly differentiated signet ring cell or mucinous adenocarcinomas and carcinomas of the Bormann type 3+4 also lead to an increased R1 rate. In order to achieve an R0 resection, an intraoperative frozen section is the standard approach. Immediate reoperation should be performed in the case of tumor infiltration. If an R1 resection is detected only in the definitive histology, surgical re-excision to achieve an R0 resection is the standard approach in publications. Nevertheless, a reoperation is rare. Only 1 study showed 122 patients with 100% re-operations, which were successfully performed in 50 patients (41% R0). For the R0 group, median survival was extended from 18 months to 23 months. There are only sporadic literature data and no evidence for postoperative additive treatment (chemotherapy, radiotherapy and radiochemotherapy).

In large parts of Europe, the Chernobyl accident of 1986 caused fallout of Cs-137. This led to the uptake of Cs-137 in trees or other materials used for bioenergy production or as firewood for domestic purposes. This Cs-137 may concentrate in the ashes of the combustion process in such a way that the clearance level of 100 Bq per kg, defined in Directive 2013/59/Euratom (EU BSS), may consequently be exceeded. There is currently no clear consensus in Europe regarding the regulatory approach to this issue: should the import and use of Cs-137 contaminated biomass and its ashes be considered as a planned exposure situation or rather as an existing exposure situation? If considered as an existing exposure situation, which reference level should be applied? We compare the approaches in various European countries, such as Finland, Norway, Sweden, Belgium and the Netherlands. Results of a recent measurement campaign performed in Belgium on firewood imported from Belarus, Ukraine and other countries show a quite large range of Cs-137 activity concentration in firewood. Analysis of samples from biomass combustion confirms that the clearance level of 100 Bq per kg Cs-137 may be exceeded even when the activity concentration in the initial pellet is trivial. A review of dose-assessment studies performed by STUK and from the literature is presented. The general context of biomass energy production is sketched: for instance, in the Netherlands, 40 large biomass firing plants (capacity > 10 MW) are operational and some 20 more are already planned. The fly ashes from the biomass combustion may be a valuable resource for the construction industry, and the issue of Cs-137 contamination is connected with the requirements of the EU BSS regarding the natural radioactivity of building materials. Assessing the impact of Cs-137 contamination and clarifying regulations in the frame of a graded approach are important elements in this context.

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