AARST_Radon_Reporter_Q42025

THE RADON REPORTER | 9 LUNG CANCER When Lung Cancer Appears Without a Smoking History I remember a 50-year-old woman who came to medical attention after falling from her horse. She had never smoked, was active and healthy, and had no obvious cancer risk factors. A computed tomography (CT) scan done for trauma revealed a lung abnormality initially thought to be a scar. Further evaluation confirmed lung adenocarcinoma, and she underwent aminimally invasive lung surgery to remove the cancer. Her story is no longer exceptional. While tobacco remains the leading cause of lung cancer, one in five people diagnosed have never smoked. This rising incidence challenges assumptions about disease risk and calls for closer examination of environmental factors. One of the most important of these factors is radon. The Atlantic Canada Lung Cancer Burden Nova Scotia has among the highest lung cancer incidence and mortality rates in Canada, and outcomes here are poorer than the national average. Many patients are diagnosed at advanced stages, when curative treatment options are limited. High rates of lung cancer in never- smokers, multiple primary cancers, and late-stage presentations suggest that tobacco alone does not explain our regional burden. The emerging concept of an “Atlantic Canadian Cancer Syndrome” points to genetic and environmental factors unique to our region. Radon exposure is a leading suspect. Radon as a Major Environmental Contributor Radon is a radioactive gas released from soil and rock. It is invisible, odorless, and tasteless. When it accumulates indoors, especially in modern, energy-efficient homes, it can reach levels that significantly increase lung cancer risk. Radon is the leading cause of lung cancer in never- smokers, the second leading cause overall, and a major contributor to lung cancer deaths in high-exposure regions. Findings from the Cross-Canada Radon Survey show that one in three homes in Atlantic Canada have radon levels at or above Health Canada’s guideline of 200 Bq/ m³ (≈5.4 pCi/L), and in Nova Scotia the proportion rises to nearly 37 percent. Many homes built since 2000 have even higher radon levels due to tighter construction and reduced ventilation. These findings have profound public health implications. How Radon Causes Lung Cancer When inhaled, radon decays into radioactive particles that lodge in the airway and lung tissue. These particles emit alpha radiation, which damages DNA, causes chromosomalinstability,andtriggersmutationsovertime. This type of damage is strongly linked to adenocarcinoma, the same form of lung cancer increasingly seen in never- smokers. Emerging biomarker research from the Evict Radon National Study is helping identify molecular signatures in lung tissue and toenails of chronic radon exposure. These tools may allow clinicians to assess cumulative radon exposure, integrate environmental risk into screening decisions, and better stratify lung cancer risk beyond smoking history. Screening Limitations and Missed Diagnoses Low-dose CT screening reduces lung cancer mortality, but eligibility is mostly based on age and smoking history. People at high risk from environmental exposures such as radon are often excluded. As a result, many cancers are diagnosed at advanced stages, when treatment is less effective. Expanding screening criteria to include environmental risk factors is an important step in early detection and saving lives. Continued on next page Radon and Lung Cancer: A Hidden Risk Alison Wallace, MD PhD FRCSC Associate Professor, Department of Surgery, Division of Thoracic Surgery, Dalhousie University Thoracic Surgeon, QEII Health Sciences Centre, Halifax, Nova Scotia, Canada Introduction: Who I Am and Why This Matters As a thoracic surgeon in Halifax, Nova Scotia, I have spent my career treating patients with lung cancer, many of whom have never smoked a single cigarette. Their stories are heartbreaking and, sadly, increasingly common. These statistics are not just numbers. They represent lives cut short and families devastated. Lung cancer is the leading cause of cancer-related death in Nova Scotia and nationwide. Yet one of its most significant contributors, radon gas, remains largely invisible to the public and under-addressed in policy. At the Indoor Environments 2025 Symposium, I shared what I have learned from clinical practice, research, and collaboration with the Evict Radon National Study. My goal was simple: to make radon visible, urgent, and actionable.