Hi, welcome back. My name is Leslie Quint. I'm from the Department of Radiology at the University of Michigan. Today's talk is entitled lymph node, or N, and distant metastasis or M staging in bronchogenic carcinoma. The objectives for this talk are to review the definitions of lymph node and distant metastasis stages in the current TNM staging system. This is the 8th edition of the classification. Along the way, we'll review imaging features that help to indicate the proper N and M stages. Let's start out with a pre-lecture question. N2 disease includes which of the following options? Metastasis to ipsilateral hilar lymph nodes. Metastasis to contralateral hilar lymph nodes. Metastasis to ipsilateral mediastinal lymph nodes. Or metastasis to contralateral mediastinal lymph nodes. Go ahead and pick your best choice, and we'll get back to this at the end of the talk. Okay, so let's dive in. The International Association for the Study of Lung Cancer recently made changes to the TNM classification system in order to better align the classification system with patient prognosis. This led to the eighth edition of the lung cancer classification system. This was released in January of 2017 worldwide, but the decision was made to hold off on implementing the system in the United States until January of 2018. Okay, so let's start out with N stage changes, and this is pretty simple. If you knew the 7th edition, then you know the 8th edition, because there are no changes to N staging in the current classification. So let's just review. The N0 category means that there are no regional lymph node metastases. In this patient, we see an FDG avid left upper lobe tumor which is over here. And there is no evidence of any spread to regional lymph nodes, so this is N0 disease. The N1 category includes tumor spread to ipsilateral lymph nodes, in the peribronchial, hilar or intrapulmonary regions. And here's an example. In this patient the primary tumor nodule is here, in the right lower lobe on this CT/PET fusion image. And we see FDG avidity in the right hilum, so that constitutes presumed N1 disease. Moving on to the N2 category, this includes tumors with tumor spread to lymph nodes in ipsilateral mediastinal or subcarinal lymph nodes. In this example on the fused CT/PET image, there is a necrotic cavitary right upper lobe primary cancer, with a region of FDG avidity in the right paratracheal region. So this a small ipsilateral mediastinal lymph node. So this is presumed N2 disease. And finally the N3 category, this includes tumors spread to lymph nodes in the contralateral hilum or the contralateral mediastinum. So let's look at an example, this patient has a spicolated right upper lobe primary cancer on CT. Here's the whole body PET image, this is the primary cancer, medially in the right upper lobe. These lymph nodes here are in the right hilum and right side of the mediastinum. So uptake in right hilar nodes would constitute presumed in one disease. Uptake in right-sided mediastinal lymph nodes is presumed in two disease, but this is the clincher, this lymph node over here. This contralateral lymph node is FDG avid, so that is presumed in three disease spread to a contralateral mediastinal lymph node. The N3 category also includes tumor spread to lymph nodes in the ipsilateral or contralateral scalene or supraclavicular lymph nodes. So in this example, the patient has a FDG avid right upper lobe primary tumor on the CT/PET fusion image. There's FDG avidity in ipsilateral mediastinal lymph node, so that's presumed in two disease. But if we look up here in the lower neck, there are FDG avid lymph nodes in the right supracavicular region, so that is presumed N3 disease. Okay, so we've looked at some CT scans, we looked at PET scans. How well do we really do in diagnosing tumor spread to mediastinal lymph nodes and in establishing the N stage. Well, let's start out with CT scanning. Unfortunately we're not very good with CT as you can see by these numbers. Our accuracy is better with PET scanning, as you can see by these numbers, but we're still not perfect. Therefore, if we see enlarged lymph nodes on CT, or FDG avid lymph nodes on PET scanning, we always try to get tissue proof before changing a patient's therapy. Let's now move on to M stage changes, and the change that has occurred from the seventh to the eighth edition is that the previous M1b category is now divided into M1b and M1c. So let's go through these sub divisions, starting with the M0 category. In this category there are no distant metastasis. We see on the CT/PET fusion image the primary cancer on the left upper lobe. Here it is on the whole body PET image with no evidence of tumor spread anywhere else, this is M0 disease. The M1a category includes metastases confined to the thorax. So in this patient we have separate tumor nodules in contralateral lobes of the lung. So just to recall, if you have two tumor nodules in the same lobe, that's T3 disease. If they're in different ipsilateral lobes, that's T4 disease, and if they're in contralateral lobes as in this patient, this is M1a disease. The M1a category also includes malignant, pleural or pericardial nodules, and a malignant pleural or pericardial effusion. This patient with lung cancer has a left pleural effusion and there are tumor nodules here along the pleural surface. And in fact, this is the hallmark for calling a malignant effusion seeing soft tissue nodules starting the pleural or the pericardial surface. So this is M1a disease. M1b, this category includes a single extrathoracic metastasis in a single organ or a distant lymph node. In this patient, there's a right lower lobe tumor mass, with a single metastasis to the brain as seen on this MR exam. This is M1b disease. And finally, M1c disease includes multiple extra thoracic metastases in one or several organs. This unfortunate patient with lung cancer had spread to the liver as we see here. To the right adrenal, the left adrenal, as well as two upper abdominal lymph nodes. So this is M1c disease. Just as we saw previously, that PET was helpful in diagnosing tumor spread to regional lymph nodes. PET is also extremely helpful in diagnosing distant metastasis, and here's such an example. This patient had a CT scan that we see on your left, and we see the primary tumor here in the right lower lobe. That was the only finding we saw on the patient's chest CT, which went down to and included the adrenal glands. We didn't see any evidence of spread of disease. However, the patient then went on to have a PET scan, and there were multiple additional abnormalities on PET, such as this one here on the liver, and this one here in the lumbar spine. So the PET here showed us previously unsuspected M1c disease. And in fact, this is well documented in the literature that PET very frequently shows us previously occult distant metastasis, thereby upstaging the disease. That brings us to our post-lecture question. N2 disease includes which of the following options? Pick your best choice. And the best choice here is metastasis to ipsilateral mediastinal lymph nodes. Okay, so that brings us to our take home points. First of all, there are no changes to the end descriptor in the new classification system. But there are changes to the M descriptor. We've seen that CT accuracy is limited for staging the regional lymph nodes. But on the other hand, PET is the preferred modality for staging regional lymph nodes as well as for detecting distant metastases. Thank you very much for your attention.
