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High windswept cliffs overlook landscaped vistas and the north Cornish coast, with waves crashing on its golden beach. This is where I grew up, and where I now live and work.  A perfect view. A perfect spot for sitting in the sun, letting light embrace one’s body.

Every organism on our planet owes its life to sunlight. Light is life, but too much of it can also mean death. Light: a source of life and a threat. A wonderful paradox.

In humans, sunlight can damage our skin and potentially cause cancer. Excessive exposure to ultraviolet radiation emitted by the sun is the most ubiquitous cause of cancer we humans are exposed to in our daily lives. But we can’t live without sunlight.

Paradoxes like this have always fascinated me and my research is based on one. I am a photobiologist doing clinical research at Royal Cornwall Hospital in Truro, right where I was born. And I added a new layer to this paradox of light. Light is life and it can be death, and in my hands is also a weapon to fight death off.

I use light’s energy to treat a form of cancer that effects the skin, called non-melanoma skin cancer, which is also primarily caused by sunlight. This technique uses visible light to activate a light-sensitive compound naturally present in cells. This compound is a precursor to haem, which is a component required for oxygen transport and energy production that exists in virtually every cell of our bodies. Once activated by light, this light-sensitive compound selectively destroys cancerous cells via a complex series of biological reactions without significantly damaging the surrounding normal skin.

We artificially induce the death process by applying a cream only to the skin area we want to treat. The cream is turned into the light-sensitive compound which transfers light energy to oxygen thus activating free radicals. As unstable and highly reactive atoms, free radicals then destroy cancer cells in the area where the cream is applied.

Serendipitously, cancer is a greedy condition that needs lots of energy to fuel its rapid growth. Cancer cells, therefore, upregulate this haem production pathway naturally and quickly produce lots of this light-sensitive compound from the cream within a few hours. During this same period of time, normal skin cells are just beginning this production process.

So here’s another paradox. Within cancers desperation for growth, we can find the key to its destruction. This gives us a window of opportunity when the activating light can be applied to destroy the cancer, while minimising unwanted damage to surrounding cells.

My research is inspired by the paradox of light and endeavours to take this process further in a bid to treat thicker skin cancers. These are not currently treated by this nurse-led therapy in an effective manner, because it is difficult for the cream to penetrate deep enough into these thicker tumours and completely destroy them.

One challenge is that the light-sensitive compound is continually being turned into haem, which is the natural end product of this biological pathway.  When this occurs, it loses its power because it cannot then transfer light to oxygen to produce free radicals. The natural conversion of the light-sensitive compound into haem requires iron. By temporarily removing free iron from cells with a second drug, we can turn off the dripping tap wasting our precious light-sensitive compound.  This results in greater accumulation within cancer cells and thus potentially more effective treatment for these thicker and very prevalent skin tumours.

We have now designed and patented a combined drug that both initiates the production of the light-sensitive compound whilst capturing iron. It’s the first step of a long and difficult drug discovery journey.

My personal path in this journey began during my undergraduate professional training year at Guy’s Hospital where I worked on clinical oncology trials with terminally ill breast cancer patients. The memories of these women still inspire me to work hard and make the most of all my opportunities and talents.

Currently my research laboratory is part of the Environment and Sustainability Institute on the Penryn Campus and I work across all four of the University of Exeter’s campuses in Devon and Cornwall.

Like light, I myself am a catalyst, a catalyst for positive change. Like a biological cascade, I think of my teaching and research as an indirect influence that amplifies down the line and ends up having a bigger impact than a single entity acting alone.

My work can be viewed as a continuous series of paradoxical trade-offs striving to find the route that is just right, a medical Goldilocks.

Edited by Alfredo Carpineti and Yara El Murr. Illustration by Ilaria Decataldo.

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