European Multidisciplinary Conference in Thoracic Oncology (EMCTO 2011) 24—26th February 2011, Lugano
Stereotactic radiosurgery treatment of lung lesions
Dr Frank Lagerwaard (University Medical Center, Amsterdam, Netherlands)
Continuing with ecancer.tv from Lugano, from the multidisciplinary conference on thoracic oncology, Dr Frank Lagerwaard, you’re here to talk about stereotactic body radiotherapy. Now, on the one hand it can be used for early lung cancer, on the other hand it can be used for metastatic disease in the lungs from other cancers. What have you got to tell us?
Basically the principle of stereotactic radiotherapy is to pinpoint a lesion with very high dose. Most experience with stereotactic radiotherapy has been obtained in early stage lung cancer but basically there is no technical difference between treating an early stage lung cancer or a lesion which is a metastasis from a disease elsewhere. With this technique you can also treat effectively one up to three lesions within the lungs, just as you could do with surgery.
And it’s described as a non-invasive and patient-friendly technique.
Yes it is. The novel linear accelerators have CT scans within the treatment machine and, as such, you don’t need inserted markers anymore, you can really see the tumour where you are aiming your radiation dose and that means that you can image the tumour on the linear accelerator and treat it at the same time. So it’s really non-invasive and the treatment duration for a patient on an outpatient basis is only a few minutes. So yes, I would think it’s patient-friendly.
Now if you’re treating metastases in the lungs then what sort of toxicity can you expect to other organs?
The toxicity of this pinpoint high dose radiotherapy, if you do it properly, is very limited and it’s mainly limited to a form of radiation reaction to the lungs several months after treatment, radiation pneumonitis that is, and that’s observed in only 3% of patients. For peripheral lesions sometimes the ribs, the chest wall, also gets a high dose and patients can suffer from some chronic pain on the chest wall and even sometimes some rib fractures are seen following stereotactic radiotherapy. But also that occurs in only 3-5% of patients.
But with stereotactic radiation you can often get double the dose that you would get otherwise and it’s very highly focussed to the right place where it’s needed. So in theory, at any rate, you could have a higher cure rate.
Yes. The cure rate is difficult to state in cases of metastatic disease but the local control rate where the lesion doesn’t grow any more has been described in several series using a biological dose of above 100 Gray as 90%, so that’s extremely high for radiation.
So good local control, that’s a conservative statement.
How much do you think this might impact survival in many of these patients, say with metastases from colorectal cancer or from somewhere else?
Well the survival is difficult to describe because it’s mainly based on your patient selection. In most of the series that have been described the overall two-year survival has been in the order of 50% which is, for metastatic disease, relatively quite long. But if you select your patients even more properly using, for instance, staging with FDG-PET you might even observe more and longer survival in patients, even with metastatic disease.
Now we don’t always have the opportunity of cherry picking patients in the real world, so how much importance do you think busy doctors should take of this sort of possibility?
If you screen suitable patients thoroughly and you confine yourself to patients with a primary tumour that is under control with no metastasis outside the lungs and just a few lesions which you have diagnosed using a spiral CT scan and PET scans, that you can bring really something to these patients. These are the patients that can obtain relatively long overall survival.
Well patient-friendly it may be but you have alternatives - you could use surgery, either non-invasive surgery, endoscopic procedures or open surgery; you could also use radiofrequency ablation. There’s quite a spectrum of modalities so where does your therapy with stereotactic radiotherapy stand among those?
For smaller lesions I think the three modalities are more or less the same with respect to the outcome. It’s very difficult to compare stereotactic radiotherapy with surgery because the follow-up of all the stereotactic radiotherapy and radiofrequency ablation studies have been relatively modest and much longer and more experience is gained with surgery for lung metastases. So that’s difficult to answer. However, the local control rates of 90% are similar to what is reported using surgery. So I think it could be a real competitor for surgery and, with all respect to radiofrequency ablation, that still is an invasive procedure and the size of the lesion is more important there than with stereotactic radiotherapy.
So what are the main points, finally, that doctors should be thinking about with all of this new knowledge that you’re gaining from stereotactic radiation for lung metastases?
Basically the concept of metastatic disease as being non-treatable, that should be forgotten. If you select your patients really carefully you can even obtain long survival in patients even with limited metastatic disease. And a local treatment doesn’t need to be very toxic.
Well, Frank Lagerwaard, thank you very much for joining us here at ecancer.tv and we will follow your news very attentively.