Breast cancer is the top cancer in women both in the developed and the developing world. The incidence of breast cancer is increasing in the developing world due to increase life expectancy, increase urbanization and adoption of western lifestyles. Although some risk reduction might be achieved with prevention, these strategies cannot eliminate the majority of breast cancers that develop in low- and middle-income countries where breast cancer is diagnosed in very late stages. Therefore, early detection in order to improve breast cancer outcome and survival remains the cornerstone of breast cancer control. According to WHO figures, worldwide, breast cancer is the leading type of cancer in women, accounting for 25% of all cases.

Humans use essential trace metals, such as iron, copper and zinc, as part of metabolic processes fundamental for life. Highly sensitive isotopic methods that were first developed for research in earth and planetary sciences are now emerging as novel tools to study how elements are taken up, used and stored by the body. Such studies can improve our understanding of previously elusive metabolic processes, inform on the causes of illnesses and may lead to the development of novel diagnostic tools.

Most elements consist of several stable, naturally occurring isotopes that can be distinguished by their atomic weight. The relative abundances or proportions of these isotopes show small variations in nature as a result of physical, chemical or biological processes. As specific reactions can produce characteristic fingerprints in these proportions, measurements of isotopic abundances can be used as a highly sensitive tool to interrogate the past and present world.

Hence, stable isotope investigations have been a key research tool of earth, environmental and planetary sciences for more than half a century. However, such investigations were traditionally limited to a few ‘light’ elements (e.g., hydrogen, carbon, oxygen and sulphur), as only these show large isotopic effects that can be readily detected.

This limitation was ameliorated in the early 2000s by analytical advances, such as the development of multiple collector-inductively coupled plasma mass spectrometry (MC-ICP-MS). This instrumentation and improved methods enabled the first studies of natural variations in the stable isotope compositions of transition metals, including iron, copper, zinc and cadmium. Such analyses are still extremely challenging as they require an instrumental precision of about 0.1% or better.

Professor Mark Rehkamper has been pioneering techniques for such measurements for a number of years and recently in collaboration with researchers from the University of Oxford has been investigating whether high precision zinc isotope measurements, originally developed for analyses of meteorite samples, can be adapted for the early diagnosis of breast cancer. Through funding from the STFC IAA the team have been able to carry out preliminary proof of concept work to assess whether zinc isotope compositions could be used to develop a novel early diagnostic tool for breast cancer. Early results have shown that changes in zinc metabolism on tumour formation in breast cancer are reflected in a change of the natural intrinsic zinc isotopic composition of the affected breast tissue. Whilst the causes are not certain, this observation implicates the potential use of high precision isotopic analysis to develop a new, early biomarker for breast cancer. The work is being further supported by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Imperial College Healthcare NHS Trust and Imperial College London.