Looking Ahead: How Climate Change Could Affect Cancer

Reading time: 4 minutes

Brittany Avin McKelvey

Climate change is a global issue with far-reaching effects on society. It is caused partly by greenhouse gases, including carbon dioxide, that trap the sun’s radiation in our atmosphere. While some warming and cooling effects are part of Earth’s natural cycle of climate change, the burning of fossil fuels and deforestation caused by humans is increasing carbon dioxide levels and causing rapid warming at an unprecedented rate. The effects of climate change are numerous, and include extreme weather events, such as hurricanes and wildfires, and ozone depletion. While these effects can devastate communities in multiple ways, climate change-related events can also increase exposure to carcinogens (or substances that can cause cancer) as well as impact access to cancer care. Cancer is the second leading cause of deaths in the world, and approximately ten million people will die due to cancer this year. As such, we need to consider the impact of climate change on cancer incidence and cancer mortality.

Exposure to Carcinogens

While the likelihood of getting cancer after exposure to a carcinogen depends upon the length and intensity of the exposure, as well as non-environmental factors such as genetics,, limiting these exposures is paramount to reducing cancer incidence. One source of increased carcinogen exposure is natural disasters and extreme weather events that are elicited by climate change. For example, climate change has caused severe wildfires that have been longer, larger, and more frequent than previous wildfires. During the burning of a wildfire, large amounts of pollutants are released, including airborne hazardous particles called particulate matter. Particulate matter does not remain in the area of the wildfire where it was released, but instead travels great distances through wind patterns, sometimes staying in the air for months. Notably, particulate matter has been linked to lung cancer incidence in numerous studies.

Another example of climate change affecting cancer risk is the link between ozone depletion and skin cancer. The sun emits ultraviolet radiation (UVR), and exposure to it is a risk factor for skin cancers such as malignant melanoma, basal cell carcinoma, and squamous cell carcinoma. UVR is mostly filtered by the Earth’s ozone layer, which provides us protection from the harmful radiation. However, the ozone layer has been steadily shrinking since the 1970s by approximately 4% every ten years. Because of ozone depletion, the United Nations Environment Program estimates that skin cancer incidence will increase in affected populations by at least 5%, with the United States projected to see a 10% increase in skin cancer by 2050. 

Access to Cancer Care

In addition to increasing exposure to carcinogens, climate change and resultant extreme weather events can impact access to cancer care. As we know, early detection of cancer through screening is important for improved outcomes. For example, if colon cancer is detected in the early stages, the 5-year survival rate is 91%, compared to an 11% survival rate if the cancer is detected late. Further, getting access to treatments and care is paramount for patients. Patients who rely on multiple appointments for prevention, diagnosis, and treatment might have their care severely disrupted when extreme weather events occur. These disruptions range from transportation to facilities, communication with providers, and power failures. For example, when Hurricane Harvey hit Houston in 2017,  producing the most rainfall on record of any United States hurricane, the ensuing flooding and citywide shutdown largely reduced the ability of patients to travel to receive treatment and delayed treatments. The effects of this were noted in patients with non-small cell lung cancer, as those who had a disruption in their treatment due to the hurricane were more likely to die. More broadly, it’s also been observed that delays in cancer diagnosis, treatment, or scans for decision-making can worsen cancer prognosis. Even without the direct hit of hurricanes or other natural disasters, disturbances to care can happen. For example, the devastation in Puerto Rico caused by Hurricane Maria closed the factory that manufactured the majority of small volume IV fluid bags used in the United States, leading to a shortage nationally as well as included at cancer-care facilities.

We need to mitigate climate change for a multitude of reasons, one being the potential effects it can have on cancer care. Because climate change increases the likelihood of severe weather events, it can also cause increased exposure to carcinogens and disruptions to access to cancer care. However, as we have begun to see with the COVID-19 pandemic, some access to healthcare can be maintained through the use of telehealth, in particular for follow-up appointments and appointments where active treatment is not occurring. Telehealth is a valuable tool in times of severe weather events and can also serve as a way to also reduce travel to care facilities, which itself contributes to climate change. The way forward for combating climate change and improving outcomes for cancer patients must be multi-pronged, and our hospitals and facilities must keep the dangers posed by climate change in mind as they plan for the future.

Edited by Emily Costa

Works Discussed: 

Leticia M. Nogueira, K. Robin Yabroff, Aaron Bernstein. Climate Change and Cancer. CA: A Cancer Journal for Clinicians. (2020) DOI: 10.3322/caac.21610

Image Credits:      

Photograph used from Pixabay, without modification.