Why do some smokers get cancer and others do not?

A groundbreaking study has revealed that genetic differences among individuals play a crucial role in determining whether someone develops cancer after exposure to carcinogens, challenging previous assumptions about the uniformity of cancer risk and progression. Published in Nature, the research analyzed nearly 600 tumors to reconstruct how cancers develop, offering new insights into why some smokers get lung cancer while others don’t, and why some non-smokers still face the disease. The findings suggest that inherited genetic factors influence both the likelihood of developing cancer and the specific pathways through which tumors evolve once they begin forming. The study was conducted using four genetically distinct groups of mice, each representing varying levels of genetic diversity similar to that found in humans. These animals were exposed to equal doses of a known liver carcinogen, diethylnitrosamine, a substance commonly found in tobacco smoke and certain processed foods. Despite receiving identical amounts of the carcinogen at the same age—15 days, the mice developed cancer through different evolutionary routes depending on their genetic makeup. While many tumors eventually activated similar biological processes that drive cancer growth, the mutations and genetic changes leading to these outcomes varied significantly. Researchers reconstructed the development of nearly 600 tumors to understand the mechanisms behind this divergence. They found that inherited DNA does not merely affect the risk of developing cancer but also influences how a tumor progresses after its initial formation. This discovery could have major implications for early detection programs and precision medicine, suggesting that future strategies for cancer prevention and diagnosis must account for inherited genetics and population diversity. Dr. Duncan Odom, who led the study while working at the Institute of Cancer Research in Cambridge before moving to Germany’s German Cancer Research Center in Heidelberg, stated that this is the first time researchers have demonstrated how inherited genetic backgrounds influence both mutation processes and tumor development pathways. “We’ve shown for the first time how much the genetic background affects the processes of mutation and the paths leading to tumor development,” he said. Sarah Aitken, a co-author of the study and assistant professor at Yale School of Medicine, emphasized the potential impact of these findings on treatment approaches. She noted that inherited genetics might also affect how patients respond to therapies that damage tumor DNA, including certain types of chemotherapy and radiation therapy. “How people react to cancer drugs likely varies based on their inherited genetics, so we may need to tailor diagnostics and treatments accordingly,” she explained. The research team highlighted that confirming these results in human populations could open the door to more personalized selection of therapies and more accurate assessment of cancer risk. If validated, the findings could lead to tailored preventive measures and targeted interventions based on individual genetic profiles. The study builds on long-standing questions in oncology regarding why individuals exposed to similar environmental risk factors often experience vastly different health outcomes. For instance, while many smokers never develop lung cancer, the disease can occur even in non-smokers. Similarly, not everyone exposed to sunlight develops skin cancer. This research provides a possible explanation rooted in genetic predispositions rather than purely environmental exposure. Experts in the field have welcomed the study, noting its significance in reshaping current understanding of cancer biology. Sam Godfrey, director of information at Cancer Research UK, described the findings as a fascinating indication that inherited genes can greatly influence how cancer develops following DNA damage. “This study gives us a fascinating clue that our inherited genes may have a big effect on how cancer develops after DNA damage,” he said. As further studies are planned to confirm these results in human subjects, the scientific community is watching closely. Researchers hope that this work will pave the way for more effective cancer prevention strategies and personalized treatment plans, ultimately improving patient outcomes.