We spoke to Professor Stephen Bown about the importance of curiosity, overcoming scientific scepticism, and how your support was vital in demonstrating the lifesaving potential of his ideas.
With a background in physics, Professor Stephen Bown's research career has focused on developing laser techniques to treat a range of diseases, particularly cancer.
Photodynamic therapy (PDT) involves the use of a drug that is triggered when activated by light. In the early 1990s, Worldwide Cancer Research awarded Professor Bown several grants to further study this innovative therapy, allowing him to propel PDT from lab to clinic.
What is photodynamic therapy?
Photodynamic therapy (PDT) uses drugs that make tissue sensitive to light, and lasers to shine light of a specific colour on the tissue and activate the drug. Alone, the drug and the light have little effect on our bodies, but in combination they have the power to kill cells. For internal cancers, the drug is usually given as a drink or by injection. For some types of early skin cancer, the drug is applied as a cream.
One of the biggest challenges in any cancer treatment is destroying cancerous cells without harming healthy tissue. Tumours are usually embedded in healthy cells and it can be hard to tell where they begin and end.
One of the benefits of PDT lies in how it affects healthy cells. Professor Bown was one of the first researchers to study this extensively, and he found that while PDT can kill living cells in normal tissue, the 'structural' tissue that holds things together, like collagen, is relatively unharmed. Keeping this structure intact means healthy cells can grow back, allowing the tissue to heal well. This has cosmetic benefits (e.g. some skin cancers can be treated without leaving scars) but also allows the treatment to reach areas in which other more destructive treatments are not be possible.
PDT is currently approved by the NHS for use in some specific cases of oesophageal, skin, and oral cancers.
It is a highly effective treatment for conditions such as Bowen's disease, where some very early cancer cells have emerged on the outermost layer of the skin.
Effectively using PDT to treat other types of cancer, and using it in combination with other cancer therapies, are active areas of research with lots more to discover.
What did your support contribute to?
Professor Bown was interested in how to use PDT to treat different types of cancer and, thanks to Curestarter support, he was able to explore how it could be used to treat pancreatic, oesophageal, head and neck, bile duct, and bowel cancers. He researched the best combinations of drugs and light sources to make the treatment work safely and effectively.
Decades later, in 2017, he was part of an international team undertaking an exciting clinical trial using a low-cost, low-powered LED device to treat early mouth cancer. Small and cheap enough to be used in rural areas with low infrastructure and no electricity, this device could be a way of treating cancer that could reach people in small villages who don’t have access to hospitals.
The method was trialed on a small group of patients in India, where lip and mouth cancers caused almost 80,000 deaths in 2022. The trial had fantastic results - 22 out of the 30 patients who participated were clear of cancer two years later - showing the huge potential this affordable technology has to transform cancer care for communities in need.
All research starts with good ideas, but resources are required to exploit them. One idea of ours was to deliver energy to the centre of a solid organ like the liver, simply by gently pushing a laser fibre through a hypodermic needle into the organ. Who would have thought that a simple idea like this would evolve into the global development of minimally invasive therapy for cancers, now often described as interventional oncology? This is the strength of Worldwide Cancer Research, recognising and supporting promising new ideas at an early stage. We are most grateful to the charity and their Curestarters for their support.
Professor Bown's timeline of discovery:
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I studied Physics at university...
...but during my PhD I decided I'd prefer to study medicine! So I trained as a medical doctor. I traveled the world working as a doctor, but wanted to learn more about how to make treatments better. -
With my unusual background of physics and medicine...
...when a job came up looking at exploring how to use lasers in medicine, I was a perfect fit! My work looking at how to stop ulcers deep inside the body from bleeding using laser light delivered by a thin optical fibre passed through an endoscope led me to wonder how we could use similar techniques to treat cancers, and I began working on photodynamic therapy. -
We knew that PDT worked to destroy cancer...
...but nobody had asked the question: how does this affect healthy tissue? This was a really important step in understanding how it could be used safely to treat patients, and I discovered that healthy tissue could heal well and recover, this opened up opportunities for treatment in many different cancer types. -
I received my first grant from Worldwide Cancer Research in 1992...
...and over the next few years this funding allowed me to explore how to safely use PDT to treat pancreatic, oesophageal, head and neck, lung, and bowel cancers. With my team, we refined the types of drugs and the kinds of light used to do PDT best. -
Over decades of research...
...we learned that PDT had huge potential to treat early cancers, especially oral, oesophageal and skin cancers, and could also be used as a palliative treatment for advanced cancers where there were no options left - to keep tumour growth in check and give people a better quality of life for a little bit longer.
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Technology kept progressing...
...and we discovered that lower power light could be used to effectively treat some cancers, using cheap, battery-powered LEDs instead of lasers. We realised this could be used as a low-cost way to treat cancers in places with less access to healthcare and resources.
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We tested this in India...
...where mouth cancer is very common. Using equipment that could be carried on a bicycle to rural health clinics without electricity, we were able to cure 22 patients with early stage oral cancer.
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I'm now retired...
...but I still work with researchers all over the world. I’m really excited about the future of PDT and how it could be used to treat many different types of cancer.
Growing up in South Africa, I spent most of my free time on the beach - and then in my late twenties I started sailing, taking many trips around the Indian Ocean and down to the Cape and back. In hindsight it wasn't really surprising to find out, several years later, that the lesions that had appeared on my face were caused by sun damage and were actually pre-cancerous Bowen's disease. Fortunately I was rapidly referred to a hospital in Stirling who carried out the PDT a week or two later, and I remember the doctor saying that it was a new treatment and I was one of his first patients to have it. I felt very lucky to be in that position and, thankfully, it meant that I didn't develop skin cancer in the longer term.
Your photodynamic therapy (PDT) FAQs:
How does photodynamic therapy (PDT) work in cancer treatment?
Photodynamic therapy is a technique that uses a drug – usually delivered in a cream or an injection – that sensitizes the body to light. A light is then shone on the affected part of the body or tumour and this activates the drug to fight cancerous cells.
Which types of cancer can be treated with PDT?
PDT can be used for lots of types of cancer, but in the UK it is approved for use for cancers of the skin, mouth and oesophagus (the part of the digestive system that connects the throat to the stomach). In future it may be possible to use PDT for internal cancers like liver or pancreatic cancer by using optic fibres inserted with a needle.
What are the risks or side effects of PDT?
PDT has relatively few side effects. The drugs that sensitize the body to light have an effect for a few hours or days, so after treatment patients have to avoid exposure to bright light. Tissue treated with PDT tends to heal very well, so the therapy can lead to less scarring or damage than traditional surgery.
How effective is PDT for early-stage cancers?
PDT is most effective when it is used for early-stage cancers, when the tumours can be isolated and the cancer hasn’t spread in the body. Using PDT at this stage can be an effective cure. However, it can also be used in late-stage cancers as palliative care with low risk of side effects, to slow tumour growth and reduce discomfort and pain.
How is light delivered to internal cancers during PDT?
PDT is mostly used for cancers that can be accessed with an endoscope – a light source on the end of a flexible tube that can be inserted into the body. This way, the treatment can be used for cancers like oesophageal and colorectal cancers. However, thin optic fibres may also be inserted using a needle into deeper organs in the body, for example in breast, liver or pancreatic cancers.
Is PDT used in combination with other treatments?
Yes, PDT may be used in combination with other cancer treatments like chemotherapy, radiotherapy or immunotherapy. Much like surgery, PDT can be used to remove the cancerous cells in tumours, and then followed up with other treatments to reduce the risk of the cancer coming back if any cells have survived.
What is the future of PDT for cancer treatment?
PDT is approved for treating mouth, skin and oesophageal cancers in the UK, but there is potential for it to be used in many other cancer types. For example, researchers are testing how it can be used for internal cancers using optic fibres. In future it may also be used to improve the effectiveness of immunotherapy, as there is evidence that the treatment can stimulate the immune system and help it find and target cancer cells.
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