Why Oncologists Should Care About Climate Change

Why care about climate change? We all know about the effects climate change will have on our planet—heat waves, droughts, floods, wildfires, and other extreme weather-related disasters—but how will that impact us as clinicians? As oncologists? And more importantly, how will it affect our patients?

It is well established that burning fossil fuels with the subsequent release of greenhouse gases causes climate change and air pollution, and that climate change causes global warming. Greenhouse gasses such as methane, carbon dioxide, and nitrous oxide trap infrared radiation and radiate it back to the surface, which warms the planet. Warmer air results in more heat-related illnesses that are aggravated by the humidity from the increased moisture that a warmer atmosphere holds. These changes will also result in increases in food-borne, water-borne, and vector-borne diseases; an increase in under-nutrition and food insecurity; an increase in incidence and severity of asthma and other respiratory diseases; and an increase in mental health problems.^1,2 These are likely to result in mass migration of climate refugees who are displaced by rising sea levels or economic scarcity, with all of the associated health issues that will befall refugees, and violent conflict resulting from competition among nations for scarcer resources. All of these adverse health effects will be disproportionately worse in our patients with cancer. As a community, we need to advocate for mitigation of our climate change footprint, and we need to make adaptations for the more difficult future we and our patients are facing.

Climate Change and the Disproportionate Burden on Patients With Cancer

Climate change is expected to have a substantial effect on the burden of infectious diseases that are transmitted by insect vectors. Rising temperatures and changing rainfall patterns lead to an increase in the number and geographic range of disease-carrying mosquitoes, fleas, and ticks. As these insect carriers, or vectors, move to new areas because of climate change and environmental degradation, diseases not normally found in those areas can spread and can jump from animals to humans, particularly with increased proximity between animals and humans. COVID-19, for example, is thought to have jumped from bats to humans, perhaps via another animal such as a pangolin, at a wet market in Wuhan, China.³ Thus, it is predicted that as the earth warms and rainfall patterns change, we will be seeing more and more pandemics in the coming decades.³ And they will have the most profound effects on our most vulnerable patients, including patients with cancer, by significantly increasing the risk of those patients contracting a contagion, as well as dying from it.

For example, Lyme disease is the most common tick-borne disease in North America. Tick survival and transmission are related to environmental factors, particularly temperature and humidity, which also affect host range. The last three decades have seen an expansion in the number of cases and geographic range. With an increase in annual average temperature of 2°C, incidence of Lyme disease in the United States is estimated to increase 21% from the rate reported from 2000 to 2016.⁴ Similarly, malaria, transmitted by the female Anopheles mosquito, is expected to make a resurgence in many areas of the world where it had been successfully contained. A temperature increase of 2°C to 3°C would increase the number of people at risk of being infected by malaria by 3% to 5% (several hundred million individuals).

Although risks may vary by tumor type, stage, therapy, and contagion, our patients with cancer will be more vulnerable than those who have intact immune systems because diseases such as Lyme disease and malaria will spread. If we use COVID-19 as an example, patients with cancer are more likely to be infected with COVID-19 than patients who do not have cancer. A study from Wuhan, China, where the COVID-19 outbreak started, revealed that the infection rate for patients with cancer was nearly double that of patients who do not have cancer; 58.3% of the patients with cancer had lung cancer.⁵ Several observational studies show that, in general, patients with cancer are at an increased risk for COVID-19 complications, including hospitalization and death. A prospective observational study from the United Kingdom analyzed 800 patients with a diagnosis of cancer and symptomatic COVID-19 between March 18 and April 26, 2020. In all, 226 patients (28%) died, and risk of death was significantly associated with advanced patient age (odds ratio [OR], 9.42; 95% CI, 6.56 to 10.02]; P < .0001), being male (OR, 1.67; 95% CI, 1.19 to 2.34]; P = .003), and the presence of other comorbidities such as hypertension (OR, 1.95; 95% CI, 1.36 to 2.80; P < .001) and cardiovascular disease (OR, 2.32; 95% CI, 1.47 to 3.64). In a case study of 218 patients who were positive for COVID-19 in New York City, a total of 61 patients with cancer (28%) died of COVID-19 compared with 149 (14%) of 1,090 patients who did not have cancer (OR, 2.45; P < .001). In all, 37% of patients with hematologic malignancies (20 of 54) and 25% of patients with solid malignancies (41 of 164) died.⁶ The COVID-19 and Cancer Consortium (CCC19) cohort study included 1,018 patients with active or previous hematologic or invasive solid malignancies. Of those patients, 26% had a combination of severe illness requiring hospitalization and/or mechanical ventilation and death.⁷

Burning fossil fuels adds carbon dioxide to the atmosphere, which causes climate change and creates air pollution in the form of fine particulate matter (particle mass with aerodynamic diameter less than 2.5 mm [PM_2.5]). PM_2.5 is related to numerous adverse health outcomes, including lung cancer, chronic obstructive pulmonary disease (COPD), and other respiratory diseases. Populations with preexisting health issues, such as respiratory diseases and lung cancer, are at an especially increased risk for harm from air-borne particulates. Recent scientific evidence has shown that the current PM_2.5 standards are too lax and should be changed.⁸

An analysis of nearly 16,000 pediatric and adolescent or young adult patients with cancer in Utah revealed that exposure to fine particulate matter was associated with increased mortality at 5 and 10 years after diagnosis of certain cancers.⁹ Patients with COPD who have never smoked are more likely to get lung cancer when compared with patients without COPD who have never smoked (hazard ratio [HR], 2.67; 95% CI, 2.09 to 3.40).¹⁰ The effects of air pollution are particularly concerning for patients with lung cancer, considering that they have two known risk factors—immunosuppression from their cancer treatment and, in most cases, an underlying lung disease. Recent epidemiologic studies have shown that exposure to air pollution increases the incidence of and mortality from lung cancer. Lung cancer risk associated with PM_2.5 exposure is the greatest for former smokers (HR, 1.44; 95% CI, 1.04 to 2.01), followed by never smokers (HR, 1.18; 95% CI, 1.00 to 1.39), and then current smokers (HR, 1.06; 95% CI, 0.97 to 1.15).¹¹ Exposure to air pollution after being diagnosed with lung cancer shortens survival. Median survival for patients with localized stage lung cancer at diagnosis was 2.4 years for those with high PM_2.5 exposure (≥ 16 μg/m³) and 5.7 years for those with low PM_2.5 exposure (< 10 μg/m³).¹²

Impact on Patient Care

Climate change will affect our ability to provide our current standard of care for patients with cancer. They will have problems accessing care because extreme weather events and/or cities under quarantine will disrupt access to health care for cancer prevention, detection, and management. Some patients may have problems getting access to medications they need, and other patients may not be able to store their medications at the temperature required to preserve maximal efficacy.¹³ Interruptions in drug supply chains and consequent shortages will occur, as has happened with the COVID-19 pandemic.^14,15 Supply chains can be disrupted, even when extreme weather events strike far from where care is delivered. For example, in 2018, when Hurricane Maria struck Puerto Rico, it caused closure of a factory that was responsible for the bulk of small-volume intravenous fluid bags for the continental United States. This led to national shortages of intravenous fluids and difficulties administering intravenous medications in many cancer treatment facilities.¹⁶

The current COVID-19 pandemic¹⁵ and recent extreme weather events have had a significant negative impact on cancer care and outcomes. Data from the electronic medical record company EPIC^14,17 show that appointments for screenings for cancers of the cervix, colon, and breast were down between 86% and 94% in March 2020 compared with average volumes in the 3 years before the first case of COVID-19 was confirmed in the United States.¹⁸ Studies are ongoing to determine whether this will result in more patients presenting with later-stage disease; however, modeling the effect of COVID-19 on cancer screening and treatment of breast and colorectal cancer over the next decade suggests that almost 10,000 excess deaths are possible.¹⁹ Accrual to clinical trials has slowed; across the National Cancer Institute’s National Clinical Trials Network, accrual dropped by about half in March and April. A 50% reduction in patient accrual to clinical trials will undoubtedly lead to delays in new treatments that would improve outcomes for patients with cancer, which could potentially have an impact on thousands of lives for years into the future.

Climate change can also block access to health care from increasing temperatures, too much or too little rain, and severe weather events. Increases in the frequency and severity of extreme weather events (heavy downpours, floods, droughts, and major storms) can cause injury, death, and displacement; can knock out power and phone lines; damage or destroy homes, roads and bridges; and affect chemical plants, oil refineries, and superfund sites, all of which increase the risk of exposure to carcinogens.¹⁶ From a health perspective, these events can impede access to medical care, reduce the availability of safe food and water, and separate people from their medicines. In 2005, Hurricane Katrina, a category 5 hurricane, caused a significant number of deaths, with more than 700 bodies recovered in New Orleans. An estimated 215 nursing home residents and hospitalized patients died, including those in Memorial Medical Center where 45 corpses were recovered. At Charity Hospital, 200 patients were not evacuated until 5 days after the hurricane, and they had been without power or fresh water during that time period. Hurricane Dorian slammed into the Bahamas with sustained winds of 185 mph, producing deluges of rain and a storm surge that was two stories high onshore, which submerged entire neighborhoods and resulted in health consequences from widespread power outages, water contamination, inoperative sanitation systems, and acute food insecurity.²¹

Climate change has had negative impacts on treatment and outcomes for patients with cancer.²¹ For example, a retrospective analysis of 1,734 patients undergoing definitive radiotherapy for non-operable locally advanced non–small-cell lung cancer during hurricane disasters and 1,734 propensity matched patients who underwent radiotherapy without being exposed to a natural disaster found that undergoing radiotherapy during a natural disaster was associated with worse overall survival; the adjusted HR was 1.19 (95% CI, 1.07 to 1.32; P = .001).²² Patients affected by a hurricane disaster had longer durations of radiation treatment (66.9 v 46.2 days; P < .001) The adjusted relative risk for death increased with the length of the disaster declaration, reaching 1.27 (95% CI, 1.12-1.44) for disasters lasting 27 days. In 2001, for example, Tropical Storm Allison, bringing with it 38.6 inches of rain, caused major damage in the Texas Medical Center, which includes Baylor College of Medicine, MD Anderson Cancer Center, and The University of Texas Health Science Center at Houston. Hundreds of thousands of research animals and tumor samples were lost, as was 25 years of research data, including, for many scientists, their life’s work.

Climate change resiliency will require major adaptations. Although overall patient visit volumes have decreased dramatically since the beginning of the COVID-19 pandemic in the United States, telehealth visits overall have increased 300-fold.²⁰ Visits for pain, depression, and anxiety—all conditions that our patients commonly have—decreased by 37%, 40%, and 31%, respectively.²⁰ In a recent article by Liu et al²³ in this journal, one health care system is leveraging telehealth experience for oncology patients during environmental disasters (wildfires) and the COVID-19 pandemic. However, telehealth will be compromised during power outages from storms, so additional creative solutions will be required to ensure continuity of cancer care.

Because severe weather events will make it more difficult to engage in face-to-face encounters, medical events will be postponed, cancelled, or presented in virtual formats. Although large-scale virtual meetings with real-time presentations and enduring presentations, slides, and videos are possible (The Community Oncology Alliance, ASCO, and the American Association for Cancer Research all reported increased numbers of attendees in 2020), the full impacts are not yet known. An editorial in The Lancet Oncology¹⁵ stated, “As a result, innumerable opportunities for discussion and collaboration will be lost, the latest research will not be presented, and patients will subsequently be affected by the delay in dissemination of information on the latest treatment to their doctors.”^15(p467)

So, yes, we owe it to our families, ourselves, and especially to our patients with cancer, to be concerned about climate change. As respected, trusted messengers, physicians play a unique role in addressing climate change.¹⁵ We can advocate for our patients by supporting health care systems in developing ways to reduce the health risks of climate change.²⁴ We can promote healthy behaviors and policies with low environmental impact, support policies to reduce the environmental footprint of society in general and the health care system in particular, advocate for appropriate preparedness for expected increased emergence of new pathogens, and undertake research and education on climate change and health.²⁵ If we promote “actions to combat climate change and lessen our use of fossil fuels [we] could prevent cancers and improve cancer outcomes, [and] we might see . . . the attainment of our mission to reduce suffering from cancer grow nearer.”^16(p242)

AUTHOR CONTRIBUTIONS

Conception and design: All authors

Collection and assembly of data: Joan H. Schiller, Steven D. Averbuch

Data analysis and interpretation: All authors

Manuscript writing: All authors

Final approval of manuscript: All authors

Accountable for all aspects of the work: All authors

AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST

Why Oncologists Should Care About Climate Change

The following represents disclosure information provided by authors of this manuscript. All relationships are considered compensated unless otherwise noted. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO's conflict of interest policy, please refer to www.asco.org/rwc or ascopubs.org/op/authors/author-center.

Open Payments is a public database containing information reported by companies about payments made to US-licensed physicians (Open Payments).

Joan H. Schiller

Consulting or Advisory Role: Genentech, AstraZeneca, Merck

Speakers' Bureau: AstraZeneca

Travel, Accommodations, Expenses: Genentech

Other Relationship: Free to Breathe, Lung Cancer Research Foundation

Steven D. Averbuch

Employment: Bristol Myers Squibb (ret)

Stock and Other Ownership Interests: Bristol Myers Squibb, Merck, Illumina, Guardant Health, Bluebird Bio, Natera, Gilead Sciences, QIAGEN, Regeneron, Exact Sciences, Editas Medicine, Moderna Therapeutics, Abbott Laboratories, Johnson & Johnson, Medtronic, Pfizer, Becton Dickinson

Consulting or Advisory Role: Caris Life Sciences, GMDx Genomics, Immunai, NeoTx, Notable Labs, NovellusDx, OrbiMed, PathAI, PMV Pharmaceuticals Pincus

Travel, Accomodations, Expenses: Caris Lifesciences

Christine D. Berg

Consulting or Advisory Role: GRAIL, Mercy BioAnalytics

Travel, Accommodations, Expenses: GRAIL

No other potential conflicts of interest were reported.