Dr Samantha Cairncross. Image: Shelley Christians

Dr Samantha Cairncross has had, since she was a young girl, a fascination with science and the microscopic bugs lurking underneath the lens of her microscope, along with the distant planets and galaxies she marvelled at through her telescope, with her late uncle, who encouraged her love for discovery.

 That fascination with science has now culminated in a revolutionary PhD thesis, which sheds light on the genetic factors that predict severe side effects from radiotherapy in head and neck cancer patients, particularly within sub-Saharan African populations. Now her discoveries will help to develop personalised radiotherapy tailored to the unique genetic diversity of African populations.

Dr Cairncross first attended Helderberg Primary School and then Bishop Lavis Primary School, where her love of science was nurtured. It also helped that her father, who has since retired, was a primary school teacher. He brought home science books that first got her hooked on science. She also credits her mother’s example as an extremely hard worker who instilled in her the values of perseverance and discipline — qualities that carried her through the long years of doctoral research, as she believes that passion has to be backed by hard work.

“Growing up in Bishop Lavis and Elsies, I saw a lot of inequality and poverty. You see, local populations suffer. I went into medical science, and as I read the literature while doing my PhD, I realised that we are not just oppressed by poverty or economic or societal standards, but we are also oppressed scientifically,” said Dr Cairncross.

Dr Samantha Cairncross. Image: Taygon Sass

Her thesis, a seven-year labour of love, sheds light on the genetic factors that predict severe side effects from radiotherapy in head and neck cancer patients, particularly within sub-Saharan African populations.

“The onset (of side effects) has been shown to be caused by genetics. In our study, we investigated the genetic factors which contribute to why patients get sick or experience side effects as a result of the treatment,” she said. 

“We found a lot of genetic markers which could determine why some patients experience side effects and others do not. Because this is the field of radiogenomics, this was the first such study conducted in sub-Saharan Africa and Africa because our populations are excluded from those studies which exist right now.” 

These side effects can seriously diminish a patient’s quality of life and may force doctors to interrupt or reduce treatment, potentially compromising the chance of a cure.

 The study found significant associations between several genetic variants and an increased risk of severe toxicities.

This research is particularly significant because it addresses a major gap in global health research.

“My journey in genetics began with a BSc in Medical Bioscience, where I was drawn to the transformative potential of genetics in healthcare. However, during my PhD, I encountered the stark reality that local genetic research is lacking in South Africa and the broader sub-Saharan region,” said Dr Cairncross.

The study’s findings could pave the way for pre-screening patients to identify those at higher risk of adverse effects, allowing for customised treatment plans that reduce toxicities without compromising treatment efficacy. Looking ahead, Cairncross and her supervisors plan to validate these findings in larger, more diverse cohorts and expand their research to include other African populations.

“The potential impact of radiogenomics in sub-Saharan Africa extends beyond improving individual patient outcomes. It could help address the growing cancer burden in developing nations while contributing to a global understanding of genetic variations in radiation response.”