Q&A Colorectal intraoperative radiotherapy
Q&A - 11TH JANUARY 2018
Colorectal intraoperative radiotherapy Consultant clinical oncologist Dr Amen Sibtain and colorectal surgeon Mr Ian Jenkins discuss a pioneering approach to treating colorectal cancers
What is intraoperative radiotherapy?
Dr Amen Sibtain: It is one of those ideas that is very simple in theory, but complex in practice. Intraoperative radiotherapy involves a surgeon operating on a patient to remove the cancer, and then a radiotherapist coming into the operating theatre and applying the radiological treatment directly onto the affected area. As a procedure it has an excellent therapeutic ratio, which means it greatly reduces the chances of the cancer returning, without incurring additional side effects.
What is the benefit of this type of surgery?
AS: Usually radiotherapy is directed onto the tumour from outside the body, and we can do this accurately and precisely. However, because the treatment is delivered externally, some normal tissues inevitably get a dose.
We want as large an effect on the tumour cells and as small an effect on the healthy surrounding cells as possible, and intraoperative radiotherapy takes this idea to the extreme. We use low energy x-rays, which only travel a relatively short distance, and direct them straight onto the tumour bed itself. The main advantage is that you can be treated in a single dose. With external radiotherapy, you have to give the treatment in multiple doses, in order to protect the healthy tissue, and space the treatments out to give the healthy tissue time to recover.
So, is this a new technique?
AS: Intraoperative radiotherapy was initially used to treat breast cancer. We are extending that principle to colorectal surgery—particularly pelvic surgery. There is a very well-established, evidence-based treatment pathway for colorectal cancers and the patient will go down that path first. This technique will be considered if the cancer has returned. This is where Mr Jenkins comes in, because he has a world-renowned reputation for taking on very difficult cases. Here at The London Clinic, we have the equipment and the physics and radiotherapy expertise to undertake this procedure.
What is the surgical perspective on the procedure?
Mr Ian Jenkins: With a tumour, a good analogy is an egg—the yolk is the tumour and the white is the margin of tissue you need to remove from around the tumour to ensure you have got all the disease—we call that the surgical margin. If we can offer a patient a sufficient surgical margin, we greatly improve their long-term prognosis. However, there are some patients for which the type or location of the tumour means that we cannot offer them a sufficient surgical margin—if the tumour is situated near to some very important organs, for example. With intraoperative radiotherapy, we may be able to offer them an alternative treatment, and change the future for that patient.
How does it differ from conventional radiotherapy?
AS: We are delivering the x-rays to a very small area in what are sometimes difficult to reach locations. You need a machine that can be manipulated easily, in order to get into the right position. You have to remember we are inside a person’s body—the surgeon will have done their best to create the right conditions for us, but we still need to be very careful not to disturb nearby organs, while getting the applicator as close to the site as possible. It means these machines are very different to the ones used for delivering standard radiotherapy.
What is the body of evidence supporting this procedure at the moment?
IJ: The results we are seeing are very good. Part of the problem is, there are not a great deal of units offering treatment for advanced and recurrent colorectal cancer. As far as we are aware, The London Clinic is the only private hospital in the UK where this specific intervention is available, so the numbers of procedures we have to reference is relatively low. Looking at the results from across Europe and the United States, though, this procedure certainly appears to have real validity in terms of disease control and overall patient survival.
AS: That is an extremely important point. Cases are few and far between, so it will take a lot longer to generate really robust clinical evidence. But what we have so far is very encouraging. However, it only remains an option for a select group of patients.
Consultant clinical oncologist Dr Amen Sibtain and colorectal surgeon Mr Ian Jenkins
What is the treatment pathway?
IJ: All patients will be referred for this particular procedure after discussions between The London Clinic’s multidisciplinary teams. The teams will take into account the nature and stage of the treatment, as well as the geography and anatomy of the disease. When it has been agreed that the patient is going to undergo this procedure, there is a great deal of planning and there are many different specialisms involved. There are the surgical and radiotherapy procedures to be worked through, there may also be a requirement for an orthopaedic or plastic surgeon, due to the nature of the surgery, and there is often a urologist involved. On the day itself, the surgery team removes the abnormality, and then Dr Sibtain and his team get to work.
AS: From our point of view, the key thing is preparation. I will have studied the scans and spoken to the rest of the team beforehand. We look at the surrounding critical structures to see if there are any important nerve pathways or organs nearby. We also go over the patient’s history very carefully to see what chemotherapy or radiotherapy they have had in the past, as that can have an impact on the dose we choose to give. It will also impact the measurements we make during the application. The procedure itself is a case of manipulating the probe until it is applied against the target area.
How and when do you decide on the radiation dosage?
AS: It is very important to get as much information as we can about the tumour. Mr Jenkins will show me the material he has removed and talk me through it. This is when we decide precisely where to apply the radiation and finalise the dose needed. We have a team of physicists who then make the calculations telling us how long the machine needs to be on for. They have to think about how well the probe is going to sit against the target tissue—if there is a gap, it impacts the way the radiation interacts with the tissue, and the size of the gap will affect the distribution. It is really important to realise that these are subtle and sophisticated calculations. We use two physicists to double-check them, and they will be in the theatre as part of the team. The procedure is a live journey—we have to adapt to what we find. We place tiny sensors around the area and onto any important organs or nerve bundles nearby, so we can measure the dose that these other areas get. So far, we are picking up virtually no dosage on any areas outside of the target area, which is excellent news.
Do you communicate much during the operation?
IJ: There’s a lot of communication beforehand—we plan the entire procedure out—so we have a timeframe in which we believe Dr Sibtain will need to be there and he comes in with his team to be ready at that point. I will then go through how the operation has gone and we will talk about the specimen. This is where he compares what he has seen intraoperatively with what he has seen in the scans beforehand and surmises the precise location of the tumour, and the required strength of the dosage.
AS: I am in the theatre about an hour in total and the time for delivering the radiotherapy is roughly 15 minutes, but of course this will be dependent on the calculations. The main determination of the length of the operation is the work that Mr Jenkins has to do.
What is the patient’s post-operative pathway?
IJ: Immediately after the surgery I am quite heavily involved, as I have to make sure the patient is recovering. The more complex the level of surgery they’ve undergone, the greater the chance of side effects or complications, so I have to monitor those closely. One of the good things about this procedure is, it has the potential to minimise the recovery period by lessening the amount of surgery that we have to perform. They will need further imaging to check progress and I will liaise with Dr Sibtain about what the images are telling us. My concern after the operation is the physical recovery of the patient, while Dr Sibtain is involved with the oncological side.
AS: One of the things that makes this such a useful treatment is that it in no way slows recovery from the major surgery. We are very careful to monitor for any post-operative side effects from the radiotherapy and as yet, we have not seen any.
What do you think is the future of this treatment?
IJ: There is an acceptance now that we can extend the breadth of treatment available for patients with advanced and recurrent colorectal cancer, and I think options like this will become more and more relevant. In the past these patients would have been told there is no hope, but now there is something we can offer them. Also, there is the possibility of designing the surgical procedure so it is less invasive, because it is optimised to work with intraoperative radiotherapy. That is something we really need to explore. If we are able to, it would improve the rapidity and quality of the patient’s recovery.
AS: Engineering and design improvements may enhance the way we can physically position the applicator as well as perhaps shorten treatment times.
What do you find most exciting about this type of work?
AS: Seeing the positive impact you and the team have on people’s lives.
IJ: For patients with advanced cancer, it is incredibly rewarding to give them a second chance, to see them start a new chapter in their lives, live longer and have an improved quality of life. That is what continues to push me onwards.
Colorectal Relating to disorders of the rectum, anus and colon.
Intraoperative An additional procedure that takes place during the course of a surgical operation.
Radiotherapy The use of high-energy rays—usually but not always x-rays—to treat disease by destroying the target cells.
Surgical margin The tissue surrounding a tumour, some of which is healthy, that is removed to ensure no diseased cells remain present.
Post-operative pathway The process the patient goes through after an operation to aid recovery.
Oncology The branch of medicine that deals with cancerous tumours.
Intraoperative radiation reduces local recurrence rates in patients with microscopically involved circumferential resection margins after resection of locally advanced rectal cancer
WJ Alberda, C Verhoef, JJ Nuyttens
(International Journal of Radiation Oncology, Biology, Physics, 2014)
Adjuvant chemoradiation plus intraoperative radiotherapy versus adjuvant chemoradiation alone in patients with locally advanced rectal cancer
Q Zhang, J Tey, Z Yang
(American Journal of Clinical Oncology, 2015)