Coffee and Conversation with Professor Hans Langendijk

Professor Johannes ‘Hans’ Langendijk was recently invited as  a distinguished speaker at the Humphrey Oei Distinguished Lecture series (HODL), where he spoke on the model-based approach when selecting patients for proton therapy. With exciting upcoming developments in the Goh Cheng Liang Proton Therapy Centre in the new NCCS building, it was perfect timing to hear from one of the world’s leading experts in Proton Therapy.

We sat down with Professor Hans for coffee and conversation to hear his thoughts on proton therapy and its exciting future.

2 things: Firstly, for your new building and the [Goh Cheng Liang] proton therapy centre, I’m impressed with the size of the facility – 4 full gantries and 1 fixed beam for research – which I think is a good idea. Patients benefit because you have a fully integrated proton therapy clinic with both research and patient care in the same place. I’m a strong believer in that integrated approach.  Proton therapy is a form of radiotherapy and should be integrated within existing radiotherapy departments. That way, patients can have access to the expertise across radiotherapy disciplines.

Secondly, NCCS has already started prospective data registration programmes, which is the backbone of a model-based approach and a rapid learning healthcare system. The team has made a number of important steps to guarantee a high quality proton therapy centre.

I had an experience with one patient nearly twenty years ago. It was a gentleman I had treated five years prior. As we sat down and talked, he told me about how he was doing. On one hand he was happy to be alive because he had advanced cancer with less than a 50% survival rate. But on the other hand, his quality of life had clearly diminished. 

This gentleman worked as an English teacher. But because of xerostomia (dry mouth – a side effect of treatment), he could not speak for longer than 10 to 15 minutes. It was impossible for him to continue as a teacher, so he moved to an administrative role, with a significant pay cut. He missed teaching his students – a great price to pay for him.

Before he was treated, one of his major leisure activities was being active in a cooking club. Again, the side effects from treatment reduced his taste and he could not take alcohol anymore. He lost his hobby and some of the friendships he made there. This encounter made me realise something to keep in mind: It’s one thing to cure, but more attention needs to be paid to side effects of treatment.

Definitely! We published a paper in the 2008 Journal of Oncology about the impact of radiation induced toxicity on quality of life. Before that time, radiation oncologists who worked with head and neck patients focused on the prevention of xerostomia (dry mouth). What we found from the study was the impact of xerostomia on general quality of life, and also social, emotional functioning, fatigue and sleeping problems. These issues were more pronounced for patients who developed dysphagia (swallowing problems). This was the start of a completely new area of research where we started looking at how to prevent dysphagia. We went from 40% Grade 2 or higher side effects, to 15% - very important for patients, so that they live well and comfortably after treatment.

We also developed 240 NTCP models (Normal Tissue Complication Probability) at different time points. This will allow us in the near future to use these comprehensive NTCP profiles to compare different treatment plans for every patient land even discuss these with our patients. I think it’s a major achievement that can be used to predict, optimise and even as a comparator for surgical approaches like robotic surgery.

One is the new radiation technique called “Flash”, where a high dose is given for one second. For conventional radiotherapy, 70Gy is given across seven weeks. What Flash does is give 40Gy in one second. What’s found is that tumour control remains the same while normal tissues are less damaged by this flash treatment. This means your therapeutic window increases. There are also pre-clinical studies that indicate that you can spare normal tissues using different fractionation schedules. This is a good thing for a patient because you can treat them in a few seconds and the tumour can be controlled. But I must stress that this is at pre-clinical study stage and a lot more research has to be done before any conclusions can be made. There are also many exciting new developments in the field of proton therapy, such as image guidance or tumour tracking. These new developments are giving answers to the treatment of moving tumours – something that was difficult just two or three years ago. 

I’d also like to mention the SPARK Trial [Stereotactic Prostate Adaptive Radiotherapy utilising KIM] (Kilovoltage Intrafraction Monitoring), another interesting development. All these help broaden the indications for proton therapy. 

I feel that there should be more emphasis on education of medical students in this field. I feel that radiotherapy is one of the most interesting medical specialties. It’s really a medical technology-driven discipline, combined with patient care. There is enough time to talk with your patients – and if you like that, this is something very appealing.