Transcript
Thank you for the kind invitation, and the introduction. The title of my presentation regards how we start a program of SRS radio-surgical program, and the benefit of the use of modern software dedicated. As what's said, the role of SRS is emerging. In particular, as you know, spine SBRT has been rapidly introduced in the clinical practice, and we have available data from retrospective and prospective study, with a large amount of patients, and with quality that higher.
So, starting from this background, we can say that results in terms of local control from this data are really satisfying because we are able to achieve 90% of local control. At one year, we can obtain complete pain response in more than 50% of the cases, and toxicity seems to be negligible. In fact, vertebral fracture are usually less than 10%, and symptomatic myelopathy are less than 1%, so really rare.
We know also that when compared with conventional radiotherapy, the effect of SRS seems to be quickly, and seems to be more durable. As what's said, we have now guidelines that allow clinician to better define the target, to try to exclude as well as possible organs at risk, of the part of the vertebra that is not affected by the disease.
However, even if we have this kind of guidelines, this is a paper published by a group of friends from ESTRO FALCON, and they obtained these impressive results because there a was a high variability in terms of the definition of the target. There is a large heterogeneity. So starting from these uncertainties related to intrafraction definition, interobserver and intraobserver definition of the target. Obviously, this kind of uncertainty can affect the precision of our treatment.
We had the pleasure to be the first center in Italy, one of the first in Europe, to have a dedicated tool for this kind of approach, for this kind of program for SRS. This tool was able to obtain an optimal multi-images alignment. As you know, we use MRI imaging, we use also PET, and it is more frequent to have a lot images to use together to define our target.
At the same way, there are a lot of uncertainties regarding the segmentation, the definition, the lineation of the target. So if we have a tool that helps us to reduce the workflow, to reduce the uncertainties using auto segmentation, we obviously can reduce the related uncertainties of the definition of the target.
At the same way, a tool that can help us to obtain a sharp dose gradient between the target and the organ at risk, you have to consider that we have spinal cord, thecal sac, we have esophagus in the tract of upper column that are really limiting those structures for the coverage of our target. So starting from that, as you also can see here, having this kind of tool, we can reduce a lot of uncertainties. This is an example of the first phase of deformable registration to correct postural setup between CT and MRI, for example.
And we can obtain rapid auto contouring starting from the CT imaging, but also fusing CT and MRI with properly selection of the sequences that could help us to define and to assess how to approach in the best way this kind of situation. This is an example of planning optimization, as you can see. We use a volumetric modulation therapy approach in our experience, and here you could see the dose distribution, and then, obviously, we send this kind of plan to the machine for the delivery of the treatment.
In this table, there is a summary of our initial experience. We started using this tool at the end of April. We recruited 16 patients for 27 lesions, and, as you can see here, there is a strict selection of the patients because the median number of the lesion was one. So there were really oligometastatic patients, and as you could see here, the primitive tumor sites are various, as well as you could have in your department.
A schedule of doses started from one session to three sessions, starting from 10 gray to arrive to 30 gray in the last patient when we implemented the simultaneous integrated boost approach. And, as you can see here, we also included the ray radiation. So very challenging situation in which, obviously, the dose was limited by the previous treatment that was done in the same patient.
Here, you can see a typical example. Obviously, we radiated only the affected part of the vertebra. We prescribed 21 gray in three fraction, and as you can see here, the region of the spinal canal was respected, but because we were able to maintain the dose under 19 gray. Another similar example here, you could see that we prescribed 21 in 3, and also here, we were able to maintain the dose under the critical limits that were suggested by literature.
Another case, more complex, we implemented recently after an update of the software also, the possibility to boost inside the part of the vertebra affected. Here you could see how it was defined in the macroscopic site of disease. It was boosted because we prescribed 27 gray in 3 fraction only in this part, and simultaneously, we treated the body of the vertebra with 24 in 3, maintaining a dose acceptable on spinal canal. Another example here, in which you can see how it's possible to obtain different doses to different parts of the same target, maintaining the limiting dose structure constraints as requested.
And now I have two cases, two practical cases to show you, to share our approach. This is a single painful metastasis on the third vertebra on the lumbar part of the column. The histology was then carcinoma of the prostate. As you could see here, the histology was really aggressive. In our department, we use routinely a PSMA PET-CT to define the disease, and as you could see here, there was a single lesion, painful, and we decide to treat this part of the vertebra, as you could see here. And in the direct comparison, before and after, you can see that we were able, after 60 days, to reduce PSMA SUV, the pain, and also the PSA without changing in hormonal therapy, obviously.
And in the previous cases, the case was not possible to submit the patient to MRI for cardiac devices. Here, we were able to perform both MRI and PET-CT with PSMA. Also here, you could see the disease on MRI and also on the PET-CT, and in this direct comparison, before and after, in the middle you could see the dose distribution. We were able to obtain what we established to obtain, what we expect. The reduction of the pain that disappeared, but also a significant reduction of SUV on PET and, obviously, reduction in terms of biochemical value of PSA.
So, obviously, this is an initial program, an initial experience, but using this tool, we demonstrated that it could be used in clinical practice in an easy way, and this tool, the software, was really useful to maximize the feasibility of spinal SRS in each phase of the procedure that are needed, obviously, to optimize the entire treatment. Thank you for the attention.
So, starting from this background, we can say that results in terms of local control from this data are really satisfying because we are able to achieve 90% of local control. At one year, we can obtain complete pain response in more than 50% of the cases, and toxicity seems to be negligible. In fact, vertebral fracture are usually less than 10%, and symptomatic myelopathy are less than 1%, so really rare.
We know also that when compared with conventional radiotherapy, the effect of SRS seems to be quickly, and seems to be more durable. As what's said, we have now guidelines that allow clinician to better define the target, to try to exclude as well as possible organs at risk, of the part of the vertebra that is not affected by the disease.
However, even if we have this kind of guidelines, this is a paper published by a group of friends from ESTRO FALCON, and they obtained these impressive results because there a was a high variability in terms of the definition of the target. There is a large heterogeneity. So starting from these uncertainties related to intrafraction definition, interobserver and intraobserver definition of the target. Obviously, this kind of uncertainty can affect the precision of our treatment.
We had the pleasure to be the first center in Italy, one of the first in Europe, to have a dedicated tool for this kind of approach, for this kind of program for SRS. This tool was able to obtain an optimal multi-images alignment. As you know, we use MRI imaging, we use also PET, and it is more frequent to have a lot images to use together to define our target.
At the same way, there are a lot of uncertainties regarding the segmentation, the definition, the lineation of the target. So if we have a tool that helps us to reduce the workflow, to reduce the uncertainties using auto segmentation, we obviously can reduce the related uncertainties of the definition of the target.
At the same way, a tool that can help us to obtain a sharp dose gradient between the target and the organ at risk, you have to consider that we have spinal cord, thecal sac, we have esophagus in the tract of upper column that are really limiting those structures for the coverage of our target. So starting from that, as you also can see here, having this kind of tool, we can reduce a lot of uncertainties. This is an example of the first phase of deformable registration to correct postural setup between CT and MRI, for example.
And we can obtain rapid auto contouring starting from the CT imaging, but also fusing CT and MRI with properly selection of the sequences that could help us to define and to assess how to approach in the best way this kind of situation. This is an example of planning optimization, as you can see. We use a volumetric modulation therapy approach in our experience, and here you could see the dose distribution, and then, obviously, we send this kind of plan to the machine for the delivery of the treatment.
In this table, there is a summary of our initial experience. We started using this tool at the end of April. We recruited 16 patients for 27 lesions, and, as you can see here, there is a strict selection of the patients because the median number of the lesion was one. So there were really oligometastatic patients, and as you could see here, the primitive tumor sites are various, as well as you could have in your department.
A schedule of doses started from one session to three sessions, starting from 10 gray to arrive to 30 gray in the last patient when we implemented the simultaneous integrated boost approach. And, as you can see here, we also included the ray radiation. So very challenging situation in which, obviously, the dose was limited by the previous treatment that was done in the same patient.
Here, you can see a typical example. Obviously, we radiated only the affected part of the vertebra. We prescribed 21 gray in three fraction, and as you can see here, the region of the spinal canal was respected, but because we were able to maintain the dose under 19 gray. Another similar example here, you could see that we prescribed 21 in 3, and also here, we were able to maintain the dose under the critical limits that were suggested by literature.
Another case, more complex, we implemented recently after an update of the software also, the possibility to boost inside the part of the vertebra affected. Here you could see how it was defined in the macroscopic site of disease. It was boosted because we prescribed 27 gray in 3 fraction only in this part, and simultaneously, we treated the body of the vertebra with 24 in 3, maintaining a dose acceptable on spinal canal. Another example here, in which you can see how it's possible to obtain different doses to different parts of the same target, maintaining the limiting dose structure constraints as requested.
And now I have two cases, two practical cases to show you, to share our approach. This is a single painful metastasis on the third vertebra on the lumbar part of the column. The histology was then carcinoma of the prostate. As you could see here, the histology was really aggressive. In our department, we use routinely a PSMA PET-CT to define the disease, and as you could see here, there was a single lesion, painful, and we decide to treat this part of the vertebra, as you could see here. And in the direct comparison, before and after, you can see that we were able, after 60 days, to reduce PSMA SUV, the pain, and also the PSA without changing in hormonal therapy, obviously.
And in the previous cases, the case was not possible to submit the patient to MRI for cardiac devices. Here, we were able to perform both MRI and PET-CT with PSMA. Also here, you could see the disease on MRI and also on the PET-CT, and in this direct comparison, before and after, in the middle you could see the dose distribution. We were able to obtain what we established to obtain, what we expect. The reduction of the pain that disappeared, but also a significant reduction of SUV on PET and, obviously, reduction in terms of biochemical value of PSA.
So, obviously, this is an initial program, an initial experience, but using this tool, we demonstrated that it could be used in clinical practice in an easy way, and this tool, the software, was really useful to maximize the feasibility of spinal SRS in each phase of the procedure that are needed, obviously, to optimize the entire treatment. Thank you for the attention.