Hi, welcome back to an Introduction to Breast Cancer. I'm Doctor Anees Chagpar. Over the last several sessions, we've talked a lot about breast cancer. We've talked about its epidemiology. We've talk about different types of breast cancer. We've talked about screening for breast cancer and ultimately getting a biopsy to find out what cancer this is. Next, let's talk about staging, because truthfully that's something that every patient has on their mind. Has this cancer spread to other parts of my body? What stage is this? How do we figure that out? Well, it's really quite simple. The AJCC, which is the commission that oversees staging, has a very simple scheme for almost all cancers. This is called TNM. TNM stands for tumor, N for nodes or lymph nodes, M for metastases or distant metastases outside of the breast and the lymph nodes. In each of those categories we rank how bad the disease is. We put the T, N and M together and that gives us a staging classification. Let's break it down. T, that's the tumor size for the invasive component. Remember back when we talked about types of breast cancer? We talked about in situ and invasive. The in situ were the pre-invasive cancers, the ones that stayed above the basement membrane, but didn't have access to blood vessels and lymph vessels. Those patients are essentially cured with just surgery alone, for the most part. Well, in terms of the TNM classification, they are classified as TIS. IS stands for in situ. They're are also T0. Next, we have the invasive cancers. Well, this is based on how big is the largest invasive component. So for tumors that the invasive tumor size is less than 2 cm, that's what we call a T1. T2 is 2 to 5 cm, T3 more than 5 cm. T4 are more aggressive tumor types. So, inflammatory breast cancers is T4. If a cancer has corroded through the muscle of the chest wall or eaten through the skin and presents with skin nodules and has gotten through the epidermis, that's T4 as well. What about N for lymph nodes? Again, it depends on how many lymph nodes have cancer. Again, when we talk about lymph nodes, we're really looking at the size of the tumor deposit. So, for tumor deposits that are less than 0.2 millimeters, that's what we call isolated tumor cells. Those really don't count so we classify those as N0. For tumor deposits more than 0.2 millimeters, those we count as micrometastases. Micrometastases and those that are more than 2 millimeters, macrometastases are all positive lymph nodes. So when we look at the end classification, we're looking at how many positive lymph nodes are there. N1, is one to three, N2, four to nine, N3, ten or more. The M is for distant metastases. Remember that these are metastases outside of the breast and the lymph nodes. So cancer that's gone to other places. To the bones or the lungs or the liver or the brain or other places. If you have distant metastases that's an M1. If you don't, M0, how easy is that? Well, when we talk about staging, we talk about two separate kind of pathways for thinking about staging. One is clinical staging. This is based on your history, physical exam and imaging. The other is the pathologic staging. What do the pathologists actually see under the microscope? Remember back when we talked about biopsies I said, tissue is the issue. Well, if we really want to know how big a cancer is. If we really want to know if it's in the lymph nodes, we need a tissue diagnosis. So, the pathologic diagnosis and the pathologic stage is often only something that we can get after we've done surgery where the pathologist now has the tumor and can measure it under the microscope giving us the T size. And actually count up how many lymph nodes have microscopic cancer cells in the lymph nodes. Before surgery, however, when a patient for example initially presents, we're really basing a lot of our judgements on the clinical stage. How big do we think it is? What do the lymph nodes feel like on our physical exam? What does the mammogram and the ultrasound show us? Now ultimately, we're going to put the TN and M together into a staging scheme. This table shows you where those stages fall out. Anybody who has in situ cancer, that is to say that T0 or TIS, those patients all have stage zero cancer. Anybody who has distant metastatic spread, spread to other organs, M1 disease, those patients have stage four. In between, that's stage one, two, and three. The higher you go, the worse it gets. But remember that all of those patients are people who can potentially be treated with curative intent. Now, I give you this table as reference, and certainly any time you have a pathology report, you can look up what T it is, what N it is, what M it is, and put it into the table to figure out what stage it is. An easy way to think about it however, is this. If you have a cancer that's less than two centimeters, and the lymph nodes are negative or maybe there's just a few microscopic cancer cells. That's a stage one. If you have a larger cancer, more than five centimeters, with positive lymph nodes, or you have many positive lymph nodes, that's a stage three. In between, stage two. That's kind of gives you a rule of thumb if you didn't want to go back and look at the table. So where does breast cancer spread? We already talked about regional spread to lymph nodes, but what about to distant organs? The main places where breast cancer spreads if it's going to spread outside of the breast and the lymph nodes is to the bone. That's the most common. Then lungs, liver, brain occasionally, and then other places. So when we're looking for distant metastatic spread, we look for where the key suspects might go. So a bone scan to see if the cancer has spread to the bones, a CT scan of the chest to see if the cancer has spread to the lungs. CT scan of the abdomen to see if it's spread to the liver. Sometimes we can do a PET scan, which would essentially take the role of the bone scan, CT scan of the chest and the abdomen. There are advantages and disadvantages to PET scan versus a bone scan, plus or minus CT scan of the chest, abdomen and pelvis, but we won't get into that. Suffice it to say that those are the staging techniques. But who should get these staging techniques to see if the cancer has spread? Well, certainly not everybody. If you have, for example, in situ disease, you know already by definition that this cancer can't spread. But should everybody with invasive disease get all of these tests? The answer is no. There have been many professional organizations that have come up with guidelines, and the guidelines are pretty uniform. Essentially, patients should only get all of these other staging studies if they are clinically stage three. Remember, clinically stage three are patients that present with bigger tumors and lots of positive lymph nodes. Now, you can imagine that for patients who have just received a diagnosis of breast cancer, they're very worried that cancer could be all over their bodies. They want this information. So, why not do all of these tests? Well, a few reasons. One is cost. But even outside of that, there's the radiation exposure. And the probability of having occult disease in other organs or all over your body, if you have clinically a stage one or two breast cancer, is very low. Take a look at this table. These are a few of the recent studies that have looked at that. So when we take patients who present with clinically stage one or two disease the chances of finding occult disease in other parts of the body, it's pretty, close to zero. However in patients with clinically stage three disease, then, the chances of finding occult disease in other organs that are distant is somewhere between six and 20%. So still pretty low but that's where you're going to get the most bang for your buck. Now, once we've staged our patients, the next thing is how do we treat them? Staging is important because it helps us to guide our treatment paradigm, but really this matters at the two extremes for the most part. So, for patients who have in situ disease, we know that these patients are not going to get chemotherapy. Why not? Because this cancer is not one which has the ability to spread to distant organs. For patients who have Distant Metastatic Disease, we know that these patients are not, in general, going to get surgery, at least not for curative intent. Why? Because surgery removes cancer in the breasts and the regional lymph nodes. And once cancer has gotten to other parts of the body, surgery then no longer becomes something that can take out all of the cancer that's there. The horse has already left the barn, as it were. In the middle, for patients who have stage one through stage three, then all modalities are possible and surgery is something that we offer to all of these patients. Because surgery can actually get rid of the cancer for curative intent. Get the cancer out of the patient, put it into a bucket, and make our patients cancer free. Over the next few sessions, we're going to talk about how we do this. How do we tailor treatments for our individual patients. Which patients need what kind of surgery? What are the surgical options? Who needs chemo and who doesn't? When does radiation play in? I hope you'll stay tuned and join me. For now, I'm Dr. Anees Chagpar, thanks for joining me.
