Global warming linked to increased cancer risk in women

By Stephen Beech

Women’s cancer risk is being driven up by global warming, suggests new research.

Higher temperatures have been linked to an increased risk of breast, ovarian, uterine, and cervical cancers.

Scientists found that climate change in the Middle East and North Africa is making breast, ovarian, uterine, and cervical cancer more common and more deadly.

They say the rise in rates is "small but statistically significant," suggesting a notable increase in cancer risk and fatalities over time.

Study first author Dr. Wafa Abuelkheir Mataria, of the American University in Cairo, Egypt, said: “As temperatures rise, cancer mortality among women also rises - particularly for ovarian and breast cancers.

“Although the increases per degree of temperature rise are modest, their cumulative public health impact is substantial.”

She said rising temperatures, compromised food and water security, and poor air quality as a result of climate change all increase the burden of disease and death worldwide.

Natural disasters and the strain of unanticipated weather conditions also disrupt infrastructure, including healthcare systems.

When it comes to cancer, the researchers say that it can mean people are more exposed to risk factors such as environmental toxins and are less likely to receive a prompt diagnosis and treatment.

The team believes the combination of factors could lead to a "major rise" in the incidence of serious cancers, but quantifying it is difficult.

To investigate the effects of climate change on women’s cancer risk, the researchers selected 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, United Arab Emirates, and Palestine.

The team says those countries are "seriously vulnerable" to climate change and are already seeing "striking" temperature rises.

They collected data on the prevalence and mortality of breast cancer, ovarian cancer, cervical cancer, and uterine cancer, and compared this information with changing temperatures between 1998 and 2019.

Co-author Dr. Sungsoo Chun, also of the American University in Cairo, said: “Women are physiologically more vulnerable to climate-related health risks, particularly during pregnancy.

“This is compounded by inequalities that limit access to healthcare.

"Marginalized women face a multiplied risk because they are more exposed to environmental hazards and less able to access early screening and treatment services.”

The prevalence of the different cancers rose by 173 to 280 cases per 100,000 people for every additional degree Celsius, according to the findings published in the journal Frontiers in Public Health.

Ovarian cancer cases rose the most and breast cancer cases the least.

Mortality rose by 171 to 332 deaths per 100,000 people for each degree of temperature rise, with the greatest rise in ovarian cancer and the smallest in cervical cancer.

When the researchers broke the figures down by country, they found that cancer prevalence and deaths rose in only six countries: Qatar, Bahrain, Jordan, Saudi Arabia, the United Arab Emirates, and Syria.

They say that could be due to "particularly extreme" summer temperatures in those countries, or other factors that the model couldn’t capture.

The rise was not uniform between countries: for example, the prevalence of breast cancer rose by 560 cases per 100,000 people for each degree Celsius in Qatar, but only 330 in Bahrain.

Although that shows that increased ambient temperature is a probable risk factor for those cancers, the research team says it also suggests that temperature has a different effect in different countries, so there are likely to be other factors modifying risk.

For example, increased heat could be associated with higher levels of carcinogenic air pollution in some places.

Dr. Chun said: “Temperature rise likely acts through multiple pathways.

“It increases exposure to known carcinogens, disrupts healthcare delivery, and may even influence biological processes at the cellular level.

"Together, these mechanisms could elevate cancer risk over time.”

She said higher prevalence could also reflect improvements in cancer screening.

Better screening would be expected to result in fewer deaths, as early-stage cancer is easier to treat.

But both death rates and prevalence rose, suggesting that the driving factor is exposure to risk factors.

Dr. Mataria said: “This study cannot establish direct causality.

“While we controlled for GDP per capita, other unmeasured factors could contribute.

"Nonetheless, the consistent associations observed across multiple countries and cancer types provide compelling grounds for further investigation.”

The research team says the study also underlines the importance of considering climate-related risks in public health planning.

Dr. Chun said: “Strengthening cancer screening programs, building climate-resilient health systems, and reducing exposure to environmental carcinogens are key steps."

She added: “Without addressing these underlying vulnerabilities, the cancer burden linked to climate change will continue to grow.”