Climate change poses several health risks, from threatening human safety, worsening existing health conditions, or jeopardizing food and water supplies. However, the impacts of climate change on cancer risk and treatment for existing patients are gaining greater attention.

“Once you've been diagnosed with cancer, there are several physical, psychological, [and] socioeconomic consequences that come with a cancer diagnosis and treatment. These can make patients who have been diagnosed with cancer more vulnerable to climate hazards,” Leticia Nogueira, PhD, MPH, scientific director of health services research in the Surveillance and Health Equity Science Department at the American Cancer Society, said in an interview with Targeted Oncology^TM.

Disruptions in Access to Care

One of the significant ways that climate change can affect patients is by making it more difficult for them to receive care. Unpredictable or more extreme weather events can make it challenging for patients to see their doctors and receive treatment.¹

Hurricane Harvey, for example, deposited more rainfall on the city of Houston, Texas, than any other United States (US) hurricane on record, resulting in serious implications for patients who were receiving cancer treatment at the time. Nogueira observed these implications when she worked on the response to Hurricane Harvey.

“One of our very first studies looked at how [patients with] lung cancer whose facility was impacted by a hurricane during their treatment had worse overall survival than patients who got treated at the same facilities but at a different time,” Nogueira said.

The study, published in JAMA, reported that patients who experienced a hurricane during their cancer treatment had a mean survival time of 29 months and a 5-year survival estimate of 14.5% compared with 31 months and a rate of 15.4%, respectively, for patients who did not experience a hurricane. Patients exposed to a hurricane also had longer durations of radiation treatment at 66.9 days vs 46.2 days for those who were not exposed, and the adjusted relative risk of death increased with the length of disaster declaration. Further, delays as short as 2 days could negatively affect survival rates for patients with non–small cell lung cancer (NSCLC).²

Rose Gerber, director of patient advocacy and education of the Community Oncology Alliance and 20-year cancer survivor, noted how natural disasters like hurricanes patients’ mental and emotional wellbeing.

“Just like an ordinary human being going through [a hurricane], it's a devastating situation. But when you're a cancer patient, your emotional distress, now that your cancer care has been interrupted, just goes to the stratosphere. It just soars. There’s the normal reaction to going through a hurricane: having no electricity, having no access to food. But now you're in treatment, and on top of that primary reaction to the horror of a hurricane, now you're even more fearful of what's going to happen to you with your cancer, because the cancer clinics are not functional, there's no electricity, the generators aren't always working. Patients don't have any way of communicating with the practices,” Gerber said in an interview with Targeted Oncology^TM.

Extreme weather events can also significantly disrupt supply chains, making it harder for treatments or medical supplies to get to patients in a timely fashion. In 2017, Hurricane Maria was responsible for the closing of a factory that provided the bulk of small-volume intravenous (IV) fluid bags for the continental US, leading to nationwide shortages of IV fluids. In 2021, Hurricane Ida damaged plastic and pharmaceutical industrial installations, further worsening a shortage of these supplies due to the COVID-19 pandemic. It also forced a diversion of shipping trucks, already in short supply, across the country. These trucks were then used for relief aid.³

However, hurricanes are not the only natural disasters that cause these deleterious disruptions to care. The 2022 Texas freeze created the worst involuntary power blackout in US history, forcing 3 semiconductor plants and railways heavily used for supply chain transport across the western US to close. In Europe, heavy rainfall in 2021 caused the banks of the Rhine River, one of Europe’s most prominent commercial waterways, to burst, resulting in days-long shipping halts.³ An ongoing drought later that year caused cargo ships to offload up to half of their usual capacity to avoid running aground.

The Cycle of Climate Change, Cancer, and Poverty

Those who have lower incomes have higher incidences of cancer and poorer survival rates.⁴ Cancer mortality is higher in rural areas, and rural areas have higher rates of poverty. Further, those in rural areas often also have less access to transportation and health care compared with those in suburban or urban areas.⁵

“In the US, people of color, including indigenous peoples, those of lower socioeconomic status, and individuals identifying as LGBTQ+ are disproportionately impacted by the detrimental effects of heat, extreme weather events, and pollution. Much of this inequity stems from the lasting legacy of historic policies such as forced relocation of indigenous people and redlining of predominantly Black neighborhoods in US cities. Consequently, marginalized populations, in general, bear markedly increased [exposure] to climate impacts because these communities are more likely to be urban heat islands and are frequently sited near highways, industrial zones, toxic waste dumps, and flood plains, leading to greater exposure to the effects of climate change and pollution,” Eva Rawlings Parker, MD, DTMH, FAAD, assistant professor of dermatology, core faculty at the Center for Biomedical Ethics and Society, and faculty leader for Diversity, Equity, and Inclusion at the Department of Dermatology at Vanderbilt University Medical Center, said in an interview with Targeted Oncology^TM.

“When combined with fewer economic resources to mitigate and adapt to these impacts, greater rates of displacement, and less access to care, disparities in the rates of health effects, including cancer incidence, is commonly observed among minority and marginalized populations. Moreover, climate events such as flooding and severe storms are more likely to disrupt cancer care in the same communities,” Parker added.

To worsen these existing burdens, climate change exploits social and economic inequities, and the World Bank estimates that climate change will push 100 million people into poverty by 2030.⁶ A significant reason for this is because rural areas have heavier reliance on climate-sensitive resources like local water supplies and farmland, as well as activities like farming and animal husbandry. Climate change can lead to droughts or too much rainfall, rendering farmland infertile. In turn, those who rely on the farmland cannot produce enough food for themselves or their livestock.⁷

As mortality from cancers, including cervical, stomach, liver, uterine, prostate, and breast,⁸ is positively correlated with high poverty, it is possible that this increase in poverty will come with an increase in deaths from these cancers in low-income populations.

Sensitive Patient Conditions

Extreme temperatures and heat waves caused by climate change can exacerbate the condition of patients with cancer due to worse immune and thermoregulatory function.⁹

“Some chemotherapy drugs, for example, can also make our thermoregulatory system, how we control our body temperature, harder to control, so patients [with cancer] can be more vulnerable to heat waves,” Nogueira said.

An analysis published in Nature estimated that over half of the known human pathogenic diseases, including tick-borne Lyme disease, malaria, and dengue can be aggravated by climate change.¹⁰ As many cancer medications can suppress the immune system, patients are especially susceptible to infection.

“In another study, we showed how [patients with cancer], who are recovering from lung cancer specifically, had worse overall survival if there was a wildfire near their house,” Nogueira said. “In addition to the wildfire smoke, of course, not good if you’re trying to recover from lung cancer surgery, there was also the issue of stress and potentially having to evacuate.” The study, published in JAMA, found that overall survival was worse for patients who underwent resection for stage I to III NSCLC who were exposed to wildfire between 3 and 12 months after hospital discharge.¹¹

Exposures to Carcinogens

Climate change, as well as a reliance on fossil fuels, also plays a role in the risk of developing cancer.

“The fracking wells, for example, can contaminate water sources. We saw the Ohio train derailment on the news on how transportation of fossil fuels can leach and increase exposure to carcinogens in the community. There is this understanding that by continuing to be reliant on fossil fuels, we are contaminating communities across the country,” Nogueira said.

The unprecedented precipitation of Hurricane Harvey, which was an estimated 3.5 times more likely to occur due to climate change, damaged chemical plants, oil refineries, and Superfund sites, releasing carcinogens into the community.¹

Longer and more prolific wildfire seasons caused by climate change have caused more pollutants to enter the air, which can travel significant distances and persist for months. Air pollution is responsible for an estimated 15% of new lung cancer cases—which is already the top cause of cancer deaths globally—and its incidence is only expected to increase.⁶

Ozone depletion also allows more harmful ultraviolet radiation from the sun to reach the Earth, leading to increased exposure to another carcinogen. According to the Skin Cancer Foundation, the incidence of melanoma and other skin cancers is expected to increase, and in the past 10 years alone, new invasive melanoma diagnoses have gone up by 27%.¹² Additionally, those who have previously had melanoma are at an increased risk of developing additional primary cancers.⁹

Health Care’s Hidden Footprint

According to the Energy Information Administration, the health care system is the second most energy-intensive industry in the US.¹ The pharmaceutical industry alone is 50% more carbon-intensive than the automotive industry, and the health care sector is responsible for an estimated 8.5% of total national greenhouse gas emissions.^13,14

Cancer treatments appear to be particularly resource intensive. A study estimated that the carbon footprint of a robotic hysterectomy for the treatment of ovarian cancer was 814 kg of carbon dioxide. It would take a 2273-mile drive—almost the distance from New York City to Las Vegas—using petroleum-based fuels to equal the same carbon dioxide output.¹⁴

Operating rooms also consume massive amounts of energy for ventilation, and anesthetic gases used in surgeries can have a greenhouse gas effect that is thousands of times more potent than carbon dioxide.¹

“There are several benefits to mitigation and adaptation, especially nowadays with incentives from the Inflation Reduction Act that can help us transition to clean energy. That ends up being more reliable, too,” Nogueira said.

“For example, emergency generators used to be on diesel. Even when they’re running for a while, they’re contaminating the communities around, and [they are] not as reliable because if there’s a disruption in the supply chain, you run out of diesel, [like with] what happened with [Hurricane] Maria in Puerto Rico [in 2017],” Nogueira continued. She proposed switching to a microgrid system that is more reliable and produces less contamination.

Other areas of consumption in health care centers can be changed to lessen the industry’s environmental impact. Nogueira, along with her co-authors, in an article published in A Cancer Journal for Clinicians, presented optimizing operating room ventilation based on occupancy and demand and capturing anesthetic gases prioritized on their warming potentials. Energy-efficient tomography and MRI machines should also be considered over less-efficient models. Even seeking to switch a hospital’s food supply to low-carbon manufacturing, shipping, and waste options could have significant impacts.¹

It's important for hospitals and cancer treatment facilities to lessen their carbon footprints as well as prepare for the realities that climate change currently presents. Stricter local building codes and federal policies are forcing health care centers to become more resilient in the face of extreme weather threats. After Hurricane Sandy in 2012, Memorial Sloan Kettering Cancer Center, in New York, went through extensive reviews to mitigate the risks of future flooding events.¹

Nogueira emphasizes the importance of these conversations on emergency preparedness happening at the individual and practices levels.

“There is a recognition that needs to come from the health care professionals to be engaged in these emergency preparedness and response [plans]—to ask our places of work, what is it that we are doing to improve the resiliency in our mitigation efforts?”

Individual Solutions for a Systemic Problem

The issue of climate change and the effects it has on patients with cancer are incredibly complex and require a multifaceted approach. Much of the onus on stopping climate change and ameliorating its effects come from the governmental and industrial levels. But experts like Nogueira assert that individuals have power to make change, especially within the health care system.

Individual actions have the potential to make impacts as well, from petitioning for better infrastructure in health care settings or opting for a food option that has a lower carbon footprint.

“Sometimes, it can get very overwhelming thinking about these, but some of these are very accessible and [cost] almost nothing,” Nogueira said. 

“All health care professionals including those of us who specialize in oncology stand at the intersection of the planetary health crisis and the needs of those for whom we care now and in the future. The planetary crisis is a triple threat of climate change, air pollution, and waning biodiversity. Successfully combatting this crisis requires mitigation and adaptation. Mitigation demands decarbonization and other actions while adaptation relies on measures to limit the effects of that triple crisis on individuals, families, and communities. Health care professionals can take action now, advocating for moving away from fossil fuels as well as addressing the need to reduce both direct and indirect greenhouse gas emissions from the healthcare industry," Sarah Hope Kagan, PhD, RN, Lucy Walker Honorary Term Professor of Gerontological Nursing, School of Nursing at the University of Pennsylvania, said in an interview with Targeted Oncology^TM.

“Adaptive measures include a huge range of opportunities to develop sustainable health care from supply chain changes through to care pathway redesign and beyond. For example, all measures to promote health and function and reduce use of acute care services among people living with cancer offer a positive impact on emissions reduction. First steps to taking effective action involve education. Few of us are experts in the planetary health crisis and what it means for people living with and after cancer and their health care. We can all learn more to do more,” Kagan added.

Gerber highlighted the unique position community oncologists are in to provide extra reassurance and create emergency preparedness plans for their patients.

“Patients are always in emotional distress when they're going through active treatment. And then when you have a natural disaster, or any anything that impedes their ability to get to their treatment, they're going to need an additional level of reassurance,” Gerber said. “I think we as providers can [let patients know] that if anything happens, we have you protected. We have you covered. There’s going to be a plan A, B, and C.”

“There are things that providers can do, and the providers really do care about their patients. And I know that as providers are going to keep trying to make things easier should any situations like this happen again,” Gerber added. 

“At the policy level, there is so much that we could all do to improve this more systemic approach universally,” Nogueira said. “Whenever physicians, as a professional body, recognize that something should be priority, let’s look at all of that. We were able to do that with COVID. When we come together…I believe there’s incredible strength.”

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