Cancer and climate change

Although the effect of climate change on cancer remains largely unquantified, a scoping review in The Lancet Oncology by Robert Hiatt, MD, PhD and colleagues indicates several pathways through which climate change increases cancer risk, incidence, and mortality. The researchers suggest various clinical, behavioral, and policy solutions that can limit climate change and minimize any potential excess cancer cases that might occur as a result. 

Global trends indicate that cancer is likely to become the leading cause of death for virtually every country in the world. The principal mechanisms through which climate change is likely to affect cancer control are through causal pathways involving air pollution, exposure to ultraviolet radiation, disruptions in food and water supply, exposure to industrial toxicants, and possibly infectious causes of cancer. Beyond these causal factors, major disruptions in the infrastructure of health-care systems for cancer control that could affect all cancers.  

Climate change is exacerbating existing social and economic inequities, within and between countries, and is leading to rising rates of migration, poverty, and conflict, which place people and communities at higher risk than normal for a range of health outcomes. Climate change and changing agricultural productivity can also negatively affect food distribution, increase food prices, and change food markets, contributing to malnutrition and food insecurity. Low-income communities and communities of color are disproportionately affected by cancer and have a higher cancer mortality than the rest of the population. The World Bank estimates that climate change will push 100 million people globally back into poverty by 2030. 

Despite the increased risks climate change poses in cancers substantial opportunities exist for policies within energy, agriculture, transportation, health care, and other sectors to substantially reduce greenhouse gas emissions, slow climate change, and avoid extreme temperature and sea-level rise, and other climate changes and their attendant health effects.  

Although climate change might increase exposure to cancer risk factors, population health interventions can offset potential increases in cancer risk through individual and community-wide behavioral and educational interventions. For example, individual behaviors such as minimizing sun exposure and using sunscreen can modulate the relationship between climate change and skin cancer. Community interventions such as the establishment of clean-air shelters can reduce exposure to air pollution during wildfire events. 

Preparing climate-resilient health systems, ensuring continuity of care during climate events, responding effectively to changes in disease burden, and providing equitable access to high-quality care are essential to protecting human health. In addition, actions by health professionals to influence the social determinants of global inequities through policy changes and political leadership are needed to address the social determinants of cancer amplified by climate change. 

In the shared worldwide battle to mitigate climate change, the international community is not on track to slow emissions of greenhouse gases. Climate change and trends in air pollution, ultraviolet radiation exposures, food production and nutrition, environmental toxicants, and perhaps the effects on infectious causes of cancer are therefore likely to continue and worsen. Even so, it might take decades to study and fully understand the impact of climate change on cancer. Known causes of cancer are becoming more prevalent in many low-income countries and are likely to challenge our ability to maintain and achieve global progress in cancer control. Notwithstanding, mitigation efforts are having some success in reducing air pollution in some parts of the world.  

At the time of writing, the world is engaged in efforts to combat a pandemic of COVID-19 that has sickened millions and killed hundreds of thousands of people across the globe. One consequence of the pandemic has been the shifting of medical resources away from cancer screening and timely treatment as the focus turns to caring for victims of the infection. The early pandemic response resulted in a striking reduction in air pollution, showing the potential of extreme measures to result in rapid environmental change. However, emissions have since rebounded nearly to pre-pandemic levels. Nonetheless, it might well be that the lessons from the present pandemic can be applied to the global challenge of climate change, including the need for investments in public health and health-care infrastructure, research, and intense collective action on health problems of a global scale 

Robert HiattRobert Hiatt, MD, PhD

Robert A. Hiatt, M.D., Ph.D., is Professor and Chair of the Department of Epidemiology and Biostatistics at UCSF, affiliated faculty at the Philip R. Lee Institute for Health Policy Studies and the Director of Population Science and Associate Director of the UCSF Comprehensive Cancer Center. His research interests include cancer epidemiology, especially breast cancer, cancer prevention and screening, health services and outcomes research, the social determinants of cancer, and environmental exposures in early development related to cancer. His central focus at UCSF is building a strong transdisciplinary research and training program in epidemiology with a focus on cancer population sciences.

 

 

Cancer and climate change. Hiatt RA, Beyeler N.Lancet Oncol. 2020 Nov;21(11):e519-e527. doi: 10.1016/S1470-2045(20)30448-4.