OCTOBER is observed as Breast Cancer Awareness Month, and I have been engaging in conversations with several breast cancer survivors about their views on the possible causes of breast cancer and its relationship with the environment. Some indicated that they have no family history of breast cancer or known genetic predisposition, while others expressed the view that stress may be a possible risk factor.

Breast cancer remains a major global public health challenge and is the most commonly diagnosed cancer among women. In 2025, a study by Joanne Kim and colleagues found that approximately one in 20 women worldwide will be diagnosed with breast cancer during their lifetime. The researchers further projected that, if current trends continue, there will be approximately 3.2 million new breast cancer cases and 1.1 million breast cancer-related deaths annually by 2050. This growing burden is expected to disproportionately affect countries with a low Human Development Index.

The Caribbean Public Health Agency has identified breast cancer as the leading cause of cancer-related deaths among women in the Caribbean region. According to the International Agency for Research on Cancer, approximately 1,310 to 1,327 new breast cancer cases are diagnosed annually in Jamaica.

Although inherited genetic mutations, such as BRCA1 and BRCA2 (breast cancer susceptibility genes), are important risk factors, genetics alone cannot explain all occurrences of breast cancer. Anecdotal accounts from survivors without a known family history further underscore the importance of exploring other possible contributing factors.

While attending a conference overseas recently, one presenter emphasised the importance of exploring the possible relationship between breast cancer and epigenetics. Particular attention was given to environmental and lifestyle exposures that may influence gene activity without altering the underlying deoxyribonucleic acid (DNA) sequence.

This emerging field of epigenetics is particularly relevant to Jamaica and the wider Caribbean, where breast cancer is a leading cancer among women and where populations may experience environmental exposures associated with contaminated water, air pollution, industrial activities, waste disposal and heavy metals, inter alia.

What is epigenetics?

Epigenetics refers to changes in gene activity influenced by behaviours, environmental factors and biological processes without altering the underlying DNA sequence. In other words, it involves potentially stable, and in some cases reversible, changes in gene expression that occur without modifying the DNA sequence. Basically, epigenetic mechanisms help determine whether particular genes are switched “on” or “off”.

By and large, we understand that cancer develops when the genetic instructions regulating how cells grow, repair themselves and die no longer function properly. While many people associate cancer primarily with inherited genetic mutations, researchers are increasingly examining another important contributor: epigenetics. This process is similar to a series of defective light switches that turn vital protective genes off without changing the basic DNA code.

The distinction between genetics and epigenetics is important. A genetic mutation involves a change in the DNA sequence itself, whereas an epigenetic alteration affects how cells read and use that DNA.

Epigenetic patterns may be influenced by ageing, diet, physical inactivity, obesity, hormones, alcohol consumption, tobacco smoke, psychosocial factors and exposure to environmental chemicals. Importantly, environmental pollutants, including certain heavy metals such as nickel, lead, chromium and arsenic, as well as air pollutants, have been associated with changes in epigenetic processes.

Epigenetics and breast cancer

In breast cancer, the cellular “instruction manuals” become disarranged in the following ways:

Silencing the body’s defenders – cells naturally contain tumour-suppressor genes that act like brakes to prevent cancer from developing. In breast cancer, a chemical malfunction can switch these genes to the “off” position. This silences the body’s natural defences, resulting in uncontrolled cell proliferation.

The 70 per cent connection – this silencing effect is common. Studies have shown that in over 70 per cent of breast cancers, at least one of four major protective genes, including the BRCA1 gene, has been switched off.

PROF ADELLA CAMPBELL.

Creating cellular chaos – when important protective genes are silenced, the rest of the cell’s DNA may lose its normal chemical boundaries, resulting in the genetic structure becoming unstable, chaotic and fragile.

Fuelling the spread – tiny cellular molecules called microRNAs (called micro ribonucleic acid) which help regulate healthy cell behaviour, may also malfunction. When these molecules dysfunction, they can help cancer cells multiply, migrate and invade healthy body tissues.

One important feature of epigenetic alterations, however, is their plasticity and potential reversibility. This distinguishes them from permanent DNA mutations.

Environmental exposures and the Jamaican context

Epigenetics provides a framework for investigating how geographical location and environmental exposures might influence breast cancer susceptibility within the Jamaican context.

Although exposure to chemicals and pollutants does not automatically result in breast cancer, research has demonstrated that certain environmental toxicants can influence epigenetic mechanisms and cellular processes associated with cancer development.

This raises important concerns for Jamaica, particularly in communities with documented environmental contamination or substantial pollution exposure that warrant further epidemiological and epigenetic investigation. These locations should be regarded as priority areas for environmental health research prior to being classified as communities with elevated breast cancer incidence.

Other locations associated with waste disposal, contaminated water, mining, industrial activities, traffic-related air pollution and agricultural pesticide use also require appropriate environmental exposure assessments to determine whether any association exists with breast cancer.

The timing of exposure is equally important and should not be overlooked. The developing breast may be particularly susceptible to environmental influences during critical periods, including prenatal development, puberty, early adulthood and pregnancy when mammary tissue undergoes substantial growth and cellular differentiation. Environmental exposures during these periods deserve investigation within the Jamaican context because they may produce long-lasting changes in gene regulation that could influence breast cancer risk later in life.

One can conclude that epigenetics provides an important link between genes, the environment and breast cancer. It offers a scientific explanation of how environmental and lifestyle exposures may influence gene activity without altering the underlying DNA sequence.

Further research into epigenetics is therefore essential and could broaden approaches to breast cancer prevention and management to include environmental monitoring and exposure assessment. By geographically mapping breast cancer cases alongside environmental factors such as pollution, pesticides and heavy metals, while controlling for individual risk factors, researchers may be better positioned to investigate potential associations.

Although several Jamaican communities are known to experience environmental pollution, current evidence does not establish that these communities have higher breast cancer rates as a result of epigenetic changes. Nevertheless, the available scientific evidence provides a rationale for investigating communities with documented pollution and chemical exposures.

Integrating cancer surveillance, environmental monitoring and epigenetic research could contribute significantly to a more comprehensive breast cancer prevention strategy for Jamaica. This approach would strengthen our understanding of the interplay between genetics, lifestyle and the environment while supporting evidence-based public health interventions aimed at reducing the burden of breast cancer.

Professor Adella Campbell is a lecturer in the College of Health Sciences, University of Technology, Jamaica.