This video features Sameera Kumar, MD presenting on Radiation and Early Stage Lung Cancer. This presentation was given at our October 20th Management of Early Stage Non-Small Cell Lung Cancer event in 2022.
Hi everyone. My name is Dr Sameer Kumar and I'm an assistant professor at the Fox Chase Cancer Center department of radiation oncology today I'll be talking about the use of S. P. R. T. And non small cell lung cancer. And I'm really focusing today on early stage non small cell lung cancer. I have no conflicts of interest to disclose today. We'll be talking about S. P. R. T. Indications. Sp R. T. Stands for steri attacked IQ body radiation therapy. S. P. R. T. Indications in early stage non small cell lung cancer. And then we'll be talking about S. P. R. T. Tools and techniques and I'm really going to go into what we do to make sure that our treatments are precise as possible and sparing as much lung tissue as possible. So let's briefly talk about the standard of care for early stage non small cell lung cancer. So the standard of care is surgical resection and we all know that surgical resection has been used for over 100 years for cure Non small cell lung cancer. With the gold standard being a lobe ectomy. This provides greater than 80% local control and the five year overall survival is 60-70%. With a five year cancer specific survival being 50-70%. Unfortunately some patients are not lobe ectomy candidates. Some of them would not be able to make it through the surgery. They're medically inoperable. They don't have healthy enough cardiopulmonary systems or something else. And some patients just do not want to go through surgery. So what do the N. C. C. N. Guidelines tell us to do with these patients. So for stage one a patient's uh every patient should have pulmonary function tests. They should have bronchoscopy. And uh you know most likely patients should be getting pathologic media style lymph node evaluation. Uh All patients should be staged with a pet scan in order to confirm that they do not have distant disease. It is important to note that a pet scan is only between 85 90% sensitive in the media steinem. Um And that's why they recommend getting a pathologic media style lymph node evaluation. If there are negative media style lymph nodes, the patient is operable. Um Then the patient will go for a surgical exploration and reception with a media style lymph node dissection. If the patient is inoperable then definitive radiation and preferably uh Saber which is the same thing as S. P. R. T. Is recommended. And Saber stands for steri attacked IQ Oblate tiv body radiotherapy. So who is eligible for S. P. R. T. So patients with tumors less than five centimeters. Now I do want to note that there are series of patients where tumors greater than five centimeters are treated with S. P. R. T. But typically tumors under five centimeters they need to be live no negative. Um So negative on pet ct but as I mentioned before a pet scan is only 85 to 90% sensitive in the media steinem. So for my patients personally I would like for them to have invasive staging with the bus or cervical media stein Oscar P. And this is because unlike patients that are going for surgery they are not going to get a media sternal lymph node dissection later on. And the implication of untreated positive lymph nodes is huge in these patients. Um And these patients, you know preferably would not be candidates for lumpectomy, lumpectomy is still standard of care. So if the patients cannot get surgery, these are the patients that we want to look at for sp. R. T. And then they need to have a tumor that's sufficiently far from what we call organs at risk. So if you have a tumor that's adhering to the esophagus or that's invading into the main stem bronchus, S. P. R. T. Is probably not the treatment of choice for these. That doesn't mean that we can't treat with radiotherapy but we can probably use fractionated radiotherapy to treat these patients instead. So what is the data for S. P. R. T. So remember that prior to S. P. R. T. Patients were being treated with fractionated radiation with a local control of only about 40 to 60% in the early two thousand's. Uh this concept of S. P. R. T. Came up and this study. R. T. O. G. 0236 was performed at indiana University it was a phase two study with 59 patients. All patients had T. One or T. Two tumors and zero and there were less than five centimeters in size. The majority of these patients had T. One tumors but there were about 1/5 of the patients had T. Two tumors. The median age was 72 years old. And then central tumors were excluded. And what do I mean by central tumors? So two tumors within two cm of the distal trachea, main stem bronchi or low bar Bronk I were excluded. And the reason for this is that there were some earlier data that showed that sP RT to these areas caused a lot of Newman itis and possibly even fatal pneumonitis. Um The treatment was 20 grade times three fractions. So a total of 60 great given every other day for 1.5 to 2 weeks. There's a technique called heterogeneity corrections which accounts for the lung being a heterogeneous tissue. So the actual dose that the tumors saw was 18 grade times three fractions. So a total of 54 gray. And on this study there was centralized quality assurance to make sure that there was high quality radiation delivered. The five year outcomes showed that primary failure was only 77.3%. there was 27% grade three toxicity. This tended to be pneumonitis or chest wall toxicity. There was 3.6% grade four toxicity and no grade five toxicity. Subsequently, some other studies have been done in this first column. You can see the study I just talked about. R. T. O. G 0236. R T O G 0915 was a study of one fraction versus four fraction. And as you can see, the local control and overall survival is somewhat similar to the three fraction regimen. R. T O G 0813 is a study that used for five fractions are five treatments in this centralized danger zone within two centimeters of the distal trachea, main stem bronchi and low bar bronchi. Now this is not a treatment for tumors that are directly in contact with those structures that is called ultra central tumors. And we won't talk about that now. But those are high risk for S. P. R. T. And again we see similar local control and overall overall survival. Most recurrences that happen after steri attacked IQ body radiation therapy are distant recurrences and most deaths that we see are not cancer related because these patients are you know, they have a lot of comorbidities. Anyway. Once we um you know in the modern era we use risk adapted dose thing when what that means is if a tumor is close to the chest wall or a tumor is especially large. We change the dose we're giving and the amount of fractions were giving. Um for example a fire fraction regimen is thought to be more gentle and so we would give a five fraction regimen instead of one or three fraction regimen. And that helps us reduce toxicity. So in large database studies grade three toxicity is 10 to 15%. Grade 43 to 5% in grade five is less than 1%. So what is the difference in the different radiation techniques that we use? We throw around words like three D. Radiotherapy, I. M. R. T. And S. P. R. T. So take a look at this panel. On the left side are prescription doses this red here it's 50 40. That's the dose we're trying to achieve. And this teal blob here shaded in is the tumor that we're trying to treat. So you can see here that this prescription dose is actually extending onto the heart somewhat. And you have these high dose areas here um that are actually higher than our prescription dose which is which is not desired. And it's actually extending onto the heart here. Um for our long toxicity we look at 20 gray um and this is extending onto the long somewhat here and here and then our our spinal cord is actually inside of the 40 gray ice a dose line. So three D. Radiotherapy is when you have a radiation oncologist deciding the position of the beams and the shapes of the beams and whatever the treatment plan you get, that's what you get. Um It's a simpler form of radiotherapy with I. M. R. T. You actually have a computer deciding your beam angles, how much dose is going through each beam, the shape of each beam and these these iterations with the computer take time. Um So this is what the computer came up with. The goal again is to cover this teal blob. And as you can see our prescription doses tighter around the teal blob. Less doses spilling out onto the heart here. You don't have as much of that orange or that high dose area um present anywhere including present in the heart. Um 20 gray ice a dose line is not as much on the lungs. And the 40 gray ice a dose line again is not covering this final cord as much SV RT or stereotyped body. Radiation therapy is a form of treating this tumor to high dose um and sparing the areas around it. So you have a tumor here being treated to a high dose and you have these very close ice a dose line. So whereas the tail blob here was the 20 gray ice a dose line here. It's the five great Caicedo's line. And you actually have a pretty rapid fall off of your dose. Um So the 20 gray isotopes line here is actually this blue line here. So how do we ensure that the patients are being treated uh in a way that's immobilizing them properly? Um So we use um different immobilization frames. These aren't the exact ones we use at Fox Chase, but basically make a mold of the patient's body and we lay them in the mold so that they are treated in the same exact position each day. We actually use a cone beam ct to image the patient daily to ensure millimeter precision. And I'll show more about that in a few seconds. So lung tumors move so the patient is living and breathing. And as the lungs are expanding and contracting the tumor is moving as well. If you're not accounting for this motion, you need to use pretty wide margins around your tumor. Five millimeters actually and 10 millimeters 10 millimeters superior li and interior early. How can we control that? Such that that margin is smaller. Well, you can restrict the patient's breathing. You can use compression, such as abdominal compression to only allow shallow breathing. You can ask the patient to hold their breath um That we don't use this as much with S. P. R. T. And that will further restrict the motion. Uh due to breathing. You can also use something called respiratory gating here on the right side. You see motion inclusive treatment. And what that means is this yellow is the entire path of the tumor. And the beam is on the entire time over this entire path. But the respirator irrigating the beam is on only when the tumor enters into this blue circle. And this blue circle is the only thing that's being treated. So when the patient is breathing in the tumor is moving up, the beam turns on and it is treated. When the patient breathes out, the tumor is not treated. And this allows us to treat a smaller volume, the 40 C. T. And inclusive um of the path is how we generally treat patients. So um a four dimensional cT where the fourth dimension is time is collected. Um as the patient is breathing. Um During the planning session, each breath is divided into 10 phases. And as C. T. Is obtained uh for each of those 10 phases, then a MIP or a maximum intensity projection is created to show the position of the tumor during each of those 10 phases. And that's what you're seeing on the right side here and then that entire tumor volume is treated and a margin is placed around it. And this is what we treat. Like I said, we do use cone beam CT s to ensure a millimeter precision. So when the patient is first placed on the treatment table, a cone beam CT is obtained. We then overlay the cT simulation which you can see in orange here with the cone beam ct, which you can see in blue here to ensure that we are exactly treating where this tumor is, each and every treatment, and that ensures that we are treating as little lung tissue as we possibly can. This also ensures that we can keep our margins around the tumor as small as possible, so that's all I have today about the treatment of early stage non small cell lung cancer using SpR T. Thank you for your time.