CANADIAN POPULATION RISK OF RADON INDUCED LUNG CANCER-VARIATION RANGE ASSESSMENT BASED ON VARIOUS RADON RISK MODELS

Outdoor Radon Dose Rate in Canada's Arctic amid Climate Change

Decades of radiation monitoring data were analyzed to estimate outdoor Radon Dose Rates (RnDRs) and evaluate climate change impacts in Canada's Arctic Regions (Resolute and Yellowknife). This study shows that the RnDR involves dynamic sources and complex environmental factors and processes. Its seasonality and long-term trends are significantly impacted by temperatures and soil-and-above water contents. From 2005 to 2022, Yellowknife's RnDR increased by +0.35 ± 0.06 nGy/h per decade, with the fastest increases occurring in cold months (October to March). The rise is largely attributable to water condition changes over time in these months, which also caused enhanced soil gas emissions and likely higher indoor radon concentrations. In Resolute, the RnDR increased between 2013 and 2022 at +0.62 ± 0.19 nGy/h (or 16% relatively) per decade in summer months, with a positive temperature relationship of +0.12 nGy/h per °C. This work also demonstrates the relevance of local climate and terrain features (e.g., typical active layer depth, precipitation amount/pattern, and ground vegetation cover) in researching climate change implications. Such research can also benefit from using supporting monitoring data, which prove effective and scientifically significant. From the perspective of external exposure to outdoor radon, the observed climate change effects pose a low health risk.

Regional cost effectiveness analyses for increasing radon protection strategies in housing in Canada

The incremental cost effectiveness ratios for implementing a recent recommendation to install a more radon resistant foundation barrier were modelled for new and existing housing in 2016, for each province and territory in Canada. Cost-utility analyses were conducted, in which the health benefit of an intervention was quantified in quality-adjusted life years, to help guide policymakers considering increasing investment in radon reduction in housing to reduce the associated lung cancer burden shouldered by the health care system. Lung cancer morbidity was modelled using a lifetable analysis that incorporated lung cancer incidence and survival time for localized, regional, and distant stages of diagnoses for both non-small cell and small cell lung cancer. The model accounted for surgical or advanced lung cancer treatment costs avoided, and average health care costs incurred for radon-attributable lung cancer cases prevented by the intervention. The incremental implementation of radon interventions in the housing stock was modelled over a lifetime horizon, and a discount rate of 1.5% was adopted. This radon intervention in new housing was cost effective in all but one region, ranging from $18,075/QALY (15,704; 20,178) for the Yukon to $58,454/QALY (52,045; 65,795) for British Columbia. A sequential analysis was conducted to compare intervention in existing housing for mitigation thresholds of 200 and 100 Bq/m³. This intervention in existing housing was cost effective at a mitigation threshold of 200 Bq/m³ in regions with higher radon levels, ranging from $33,247/QALY (27,699; 39,377) for the Yukon to $61,960/QALY (46,932; 113,737) for Newfoundland, and more cost effective at a threshold of 200 than 100 Bq/m³. More lung cancer deaths can be prevented by intervention in new housing than in existing housing; it was estimated that the proposed intervention in new housing would prevent a mean of 446 (416; 477) lung cancer cases annually. The cost effectiveness of increased radon resistance in foundation barriers in housing varied widely, and would support adopting this intervention in new housing across Canada and in existing housing in higher radon regions. This study provides further evidence that the most cost effective way of responding to the geographically variable radon burden is by implementing specific regional radon reduction policies.

Indoor radon exposure and excess of lung cancer mortality: the case of Mexico-an ecological study

Radon is a radioactive gas that can migrate from soils and rocks and accumulate in indoor areas such as dwellings and buildings. Many studies have shown a strong association between the exposure to radon, and its decay products, and lung cancer (LC), particularly in miners. In Mexico, according to published surveys, there is evidence of radon exposure in large groups of the population, nevertheless, only few attention has been paid to its association as a risk factor for LC. The aim of this ecological study is to evaluate the excess risk of lung cancer mortality in Mexico due to indoor radon exposure. Mean radon levels per state of the Country were obtained from different publications and lung cancer mortality was obtained from the National Institute of Statistics, Geography and Informatics for the period 2001-2013. A model proposed by the International Commission on Radiological Protection to estimate the annual excess risk of LC mortality (per 10⁵ inhabitants) per dose unit of radon was used. The average indoor radon concentrations found rank from 51 to 1863 Bq m^-3, the higher average dose exposure found was 3.13 mSv year^-1 in the north of the country (Chihuahua) and the mortality excess of LC cases found in the country was 10 ± 1.5 (range 1-235 deaths) per 10⁵ inhabitants. The highest values were found mainly in the Northern part of the country, where numerous uranium deposits are found, followed by Mexico City, the most crowded and most air polluted area in the country. A positive correlation (r = 0.98 p < 0.0001) was found between the excess of LC cases and the dose of radon exposure. Although the excess risk of LC mortality associated with indoor radon found in this study was relatively low, further studies are needed in order to accurately establish its magnitude in the country.

Non-Small Cell Lung Cancer in Young Patients: An Analysis of Clinical, Pathologic and TNM Stage Characteristics Compared to the Elderly

Purpose

To compare clinicopathologic factors including tumor-node-metastasis (TNM) stage between young and elderly patients with non-small cell lung cancer (NSCLC).

Methods

This retrospective study compared the following characteristics between 52 young patients with NSCLC (<50 years of age) and 67 elderly patients with NSCLC (>60 years): duration of symptoms before medical consultation, smoking index, family history of cancer, Ki-67 index, and pTNM stage. A binary logistic regression analysis was used to identify factors predictive of greater stage NSCLC (stage III/IV compared to stage I/II) within each age group.

Results

The incidence of adenocarcinoma was higher in the young than in the elderly (P=0.006). Smoking index (P=0.002) and Ki-67 index (P<0.001) were lower in the young than in the elderly. In young patients with NSCLC, delayed treatment (greater duration from symptoms to medical consultation, P=0.050) and active tumor proliferation (higher Ki-67 index, P=0.003) were predictive of more advanced cancer stage (III/IV), with only symptom duration being predictive of stage III/IV NSCLC among elderly patients. Among young patients, cough (P=0.021) and chest congestion (P=0.040) were the most significant warning symptoms of advanced-stage NSCLC.

Conclusion

High tumor proliferation and delayed treatment are predictive of advanced NSCLC on presentation among young individuals. Early diagnosis by imaging, such as with the use of low dose computed tomography (LDCT), for young individuals with coughing and chest congestion over 1 month might be effectiveto improve prognosis and outcomes.

Estimates of the Lung Cancer Cases Attributable to Radon in Municipalities of Two Apulia Provinces (Italy) and Assessment of Main Exposure Determinants

Indoor radon exposure is responsible for increased incidence of lung cancer in communities. Building construction characteristics, materials, and environmental determinants are associated with increased radon concentration at specific sites. In this study, routine data related to radon measurements available from the Apulia (Italy) Regional Environmental Protection Agency (ARPA) were combined with building and ground characteristics data. An algorithm was created based on the experience of miners and it was able to produce estimates of lung cancer cases attributable to radon in different municipalities with the combined data. In the province of Lecce, the sites with a higher risk of lung cancer are Campi Salentina and Minervino, with 1.18 WLM (working level months) and 1.38 WLM, respectively, corresponding to lung cancer incidence rates of 3.34 and 3.89 per 10 × 10³ inhabitants. The sites in the province of Bari with higher risks of lung cancer are Gravina di Puglia and Locorotondo, measuring 1.89 WLM and 1.22 WLM, respectively, which correspond to an incidence rate of lung cancer of 5.36 and 3.44 per 10 × 10³ inhabitants. The main determinants of radon exposure are whether the buildings were built between 1999 and 2001, were one-room buildings with porous masonry, and were built on soil consisting of pelvis, clayey sand, gravel and conglomerates, calcarenites, and permeable lithotypes.