Tumor Staging

00:01 Okay. That's “Grading” - How does the tumor look down the microscope? “Staging” on the other hand general principles, this takes into account, everything that is known about the patient, not just under the microscope so whether there's metastatic disease.

00:16 What other parts of the tumor have affected in terms of the original site of origin, that kind of stuff.

00:24 So, the tumor staging is through a “TNM” system.

00:29 The “T” stands for tumor size and location and depth of invasion and in these TNM systems, it's also unique for every tumor type.

00:39 So, lung cancer has a different TNM system, than does prostate cancer, than does breast cancer, than does brain cancer, so, we've developed a different TNM system for them all and again, don't expect you to memorize those, but to be aware of those, because they impact prognosis and therapy.

00:57 So, “T” in the TNM system stands for tumor size location depth of invasion.

01:02 “N” stands for lymph node involvement, whether it's positive or not and the total lymph nodes that are involved.

01:08 So, the T grade can be for example, T1 to T4 depending on the size and location and depth of invasion.

01:17 The nodal involvement can be N0, no nodes, N1, one node, N2 more than one node.

01:26 So, again the staging here depends on the particular TNM system in the particular tissue.

01:33 And “M” is whether there are distant metastasis present or absence.

01:38 For every distinct tumor type, that TNM value, is translated to a stage 1-4.

01:44 And as I said before, every single one of these TNMs, varies from tumor type and tissue.

01:51 So, the long TNM system is different than the prostate, is different than the breast etc.

01:58 The important thing about this staging system, which also, sometimes incorporates the grade as well, it allows patients to be categorized into high risk, medium risk, low risk for bad outcome.

02:11 And that will tell us whether to be very aggressive with their therapy or whether we can be a little bit more laissez faire about that.

02:19 Okay. So, when you become oncologist, you will learn this system for your specialty tumor.

02:26 Right now, just be aware that that's how grading and staging works.

02:31 Let's think for a minute now about staging, just a good example is colorectal cancer staging and on this image, we're looking down the barrel of this colon, we have the lumen, we have the mucosa where cancers are going to originate, we have the submucosa, we have the muscularis propria, and we have the serosal outer lining.

02:54 If a tumor is reasonably small and is it's constrained to either, the epithelium or minimally invasive into the submucosa, then it's a stage one tumor.

03:06 If it is more deeply invasive into the muscularis propria, then it's a stage two tumor.

03:12 If it goes all the way through the muscularis mucosa and into the serosal surface, this is a stage three tumor, and a stage four tumor, will have lymph node metastasis.

03:25 So, that's kind of gives you a general sense of how we would do staging, say in colon cancer.

03:31 Why do we care about all this? I’ve already kind of mentioned it.

03:35 What stage you are at the time of your diagnosis, will tell you and your oncologist your survival likelihood and how aggressive you should be in therapy.

03:48 So, stage 0, is actually carcinoma in situ, in colon cancer staging, it doesn't invade beyond the basement membrane and stage 1, stage 2, stage 3, and stage 4, are what you see in the different colors and you can see that if you're stage 4 disease with colon cancer, you have a very poor prognosis.

04:10 In fact, about half of the patients with that will be dead within 10 months, pretty amazing.

04:16 So, that says in that population based on the staging characteristics, I’m going to be really hyper-aggressive, if I’m going to try to treat and help that patient.

04:25 Stage 3 disease in comparison, has about a 50% mortality at more like three years, okay and then stage 2, stage 1, stage 0, etc.

04:36 So, this allows us to stratify risk, stratify prognosis and stratify potentially therapy and with that, we've kind of covered grading and staging.