Climate change may be contributing to a small but notable increase in the incidence and mortality rates of breast, ovarian, endometrial, and cervical cancers in the Middle East and North Africa, according to a recent study published by Mataria and Chun in Frontiers in Public Health.
Background
Rising temperatures, compromised food and water security, and poor air quality have all been shown to increase the burden of disease and mortality globally. Natural disasters and the strain of unanticipated weather conditions also disrupt infrastructure, including health-care systems. As a result of climate change, the combined exposure to risk factors such as environmental toxins and the lower likelihood of receiving prompt diagnoses and treatments may lead to a significant rise in cancer incidence. However, quantifying this increased risk has been challenging.
“Women are physiologically more vulnerable to climate-related health risks, particularly during pregnancy,” explained co–study author Sungsoo Chun, MPH, PhD, of the American University in Cairo. “This is compounded by inequalities that limit access to health care. Marginalized women face a multiplied risk because they are more exposed to environmental hazards and less able to access early screening and treatment services,” he continued.
Study Methods and Results
In this study, investigators examined the effects of climate change on breast and gynecologic cancers among a sample of 17 Middle Eastern and North African countries—Algeria, Bahrain, Egypt, Iran, Iraq, Jordan, Kuwait, Lebanon, Libya, Morocco, Oman, Qatar, Saudia Arabia, Syria, Tunisia, the United Arab Emirates, and Palestine—that are currently vulnerable to climate change and are already recording considerable temperature rises. They compared the data with changing temperatures between 1998 and 2019.
“As temperatures rise, cancer mortality among women also rises—particularly for ovarian and breast cancers,” stressed co–study author Wafa Abuelkheir Mataria, PhD, of the American University in Cairo. “Although the increases per degree of temperature rise are modest, their cumulative public health impact is substantial,” she added.
The investigators found that the prevalence of cancer rose by 173 to 280 cases per 100,000 individuals for every additional degree Celsius. For instance, ovarian cancer cases increased the most and breast cancer cases, the least. Mortality rates rose by 171 to 332 deaths per 100,000 individuals for each degree of temperature rise, with the greatest increases observed in ovarian cancer and the lowest increases in cervical cancer.
After examining the data by country, the investigators revealed that cancer prevalence and mortality rose in six countries: Qatar, Bahrain, Jordan, Saudia Arabia, the United Arab Emirates, and Syria. Further, the uptick in cancer incidence and mortality did not appear to be uniform among the countries. The investigators noted that the prevalence of breast cancer rose by 560 cases per 100,000 individuals for each degree Celsius in Qatar but 330 cases per 100,000 individuals in Bahrain. They hypothesized that the findings may have been the result of the extreme summer temperatures experienced in these countries or other factors that could not be captured by their model.
Conclusions
Although this demonstrated that increased ambient temperatures may be a probable risk factor for these cancers, the results also suggested that temperature could have a different effect in several countries. The investigators emphasized that there are likely to be other factors modifying the risk of cancer incidence and mortality. They suggested that increased heat may be correlated with higher levels of carcinogenic air pollution in some regions.
“Temperature rise likely acts through multiple pathways. It increases exposure to known carcinogens, disrupts health-care delivery, and may even influence biological processes at the cellular level. Together, these mechanisms could elevate cancer risk over time,” Dr. Chun postulated.
The higher prevalence of cancer incidence may also reflect improvements in cancer screening. Nonetheless, the investigators expected that enhanced screening would result in fewer deaths, since early-stage cancer is typically easier to treat. Because both mortality and prevalence rates rose, the driving factor may instead be exposure to risk factors.
“This study cannot establish direct causality,” cautioned Dr. Mataria. “While we controlled for [gross domestic product] per capita, other unmeasured factors could contribute. [T]he consistent associations observed across multiple countries and cancer types provide compelling grounds for further investigation,” she underlined.
The investigators highlighted the importance of considering climate-related risks in public health planning.
“Strengthening cancer screening programs, building climate-resilient health systems, and reducing exposure to environmental carcinogens are key steps,” underscored Dr. Chun. “Without addressing these underlying vulnerabilities, the cancer burden linked to climate change will continue to grow,” he concluded.
Disclosure: For full disclosures of the study authors, visit frontiersin.org.
