 Hello everyone welcome back to another session in dentistry and more today. We have TNM staging. It is a very small topic so the TNM system which is used to describe the anatomical extent of head and a cancer and is based on the assessment of three basic components that is the extent of a tumor which is denoted by tree and the presence or absence and extent of regional lymph node metastasis denoted by N and the final one is The presence or absence of distant metastasis. Okay, so this is a distant metastasis. This is an order with regional metastasis So let's learn TNM. So we'll start with the extent of tumor. So extent of tumor we have tx t0 T1, T2, T3, T4A and T4B Tx is nothing but primary tumor which cannot be assessed. T0 is no evidence of primary tumor Tis which is Casinoma in situ T1 is tumor which is 2 centimeter or less. Okay, so 2 centimeter or less in dimension T2 is a tumor which is greater than 2 but lesser than 4 centimeter whereas T3 is greater than 4 centimeter Now we have T4A and T4B T4A is moderately advanced local disease. That means it invades through cortical bone Inferior alveolar now floor of the mouth or skin of face that is chin nose or oral cavity Tumor invades adjacent structures through the cortical bone Into deeper muscles or muscles of tongues such as genioglossus Hypoglossus palatoglossus And maybe even in maxillary sinus. So that advanced stage is T4A And T4B is very advanced. That means tumor invades mastigatory space Terugoid plates or skull base and Nks is the internal carotid artery So that is about the extent of tumor. It is basically the dimension 2 centimeter 2 to 4 more than 4 and its Inversion to the adjacent local structures Whereas a nodal involvement which is again Nx, N0, N1, N2, N2A, N2B, N2C and N3 Nx is regional lymph nodes cannot be assessed N0 is there is no regional node metastasis N1 is Metastasis in a single Ipsilateral lymph node that is 3 centimeter or less in greater dimension. Okay, that is N1 3 centimeter or lesser in dimension So N1 is Ipsilateral lymph nodes Ipsilateral means only on one side of the One side not on the contralateral side. Okay, it is occurring on the left side or right side Whereas N2 Where the metastasis in a single Ipsilateral lymph node And the dimension is more than 3 mm, but not more than 6 mm 3 to 6 Not a millimeter centimeter Or we can see it as a multiple Ipsilateral lymph nodes But none more than 6 centimeter in dimension or in bilateral or contralateral lymph nodes That is N2 Whereas N2A That is metastasis in a single Ipsilateral lymph node More than 3 centimeter, but not more than 6 centimeter. That is various categories of N2 Because it includes Ipsilateral and bilateral category but the dimension is 3 to 6 centimeter. So N2A is Single Ipsilateral N2B is multiple Ipsilateral N2C is bilateral Nodal involvement, but none greater than 6 centimeter it is all 3 to 6 centimeter dimension that is the greatest dimension of the nodes is up to 6 centimeter That is N2A 2B 2C 2A is Ipsilateral single multiple Ipsilateral and this is bilateral N3 is metastasis in a lymph node which is more than 6 centimeter in greatest dimension that is more than 6 centimeter So that is about nodal involvement And the metastasis that is M is very simple M0 or M1 that is distant metastasis is absent Distant metastasis is present Okay So staging is very simple one, but understanding this is little bit tricky INSITO is a different concept rather than 1, 2, 3 and 4 INSITO is nothing but Where actually there is carcinoma is localized very localized in that position T1 is 2 centimeter. This is 2 to 4. This is more than 4 and 4A and 4B are It is extented to invades to local structures And the nodal involvement is 3 centimeter. N2 is 3 to 6 centimeter. It has three categories Ipsilateral single Ipsilateral multiple and bilateral whereas N3 is more than 6 centimeter and M0 and M1 The TNM staging has 4 stages that is stage 0, 1, 2, 3, 4 based on the involvement of TN and M So stage 0 is tumor INSITO where the nodal involvement or metastasis is absent Stage 1 is T1 that is less than 2 centimeter And N0, M0 stage 2 is T2 where the Dimension is 2 to 4 centimeter N0 and M0 stage 3 has 4 Types that is 4 way it can become a stage 3 Cancer so it could be T1, T2, T3 With the presence of N1 M0 is anyway not present T1, T2, 3, 3 presence of N1. N1 is 3 centimeter Regional lymph node extension But if it is T3 and N0 also it become stage 3. So T3 With the presence of N0, N1 it will become stage 3. Rest all T1, T2 with the presence of N1 and M0 Stage 4 has 3 category A, B, C. Stage 4A, 4B and 4C 4A is we know we have here T4A and T4B T4A with N0, M0 T4A with N1, M0 Then T1, T2, T3 with the presence of N2. N2 is 3 to 6 centimeter nodal extension With M0 and T4A with N2 also become stage 4A Whereas stage 4B is T4B Any N, M0 Or any T, N3, M0 And stage 4C which is the most advanced relation any T any N with the presence of M1 So M1 is only coming here that is the distant metastasis So what is the benefit of this peculiar staging? So it always helps us to plan the therapy It indicates the prognosis. It helps us to compare the result of treatment It facilitates exchange of information between treatment centers And there are lots of limitations for this TNM staging Especially with regard to the T staging It is a crude system and tumor size not consistently related to the prognosis And it is debatable. The boundaries are debatable Where the tumor and the T is measuring And it can be difficult to accurately assess the clinical extent And there will be lots of inconsistencies and omissions Regarding the nodal staging There will be lots of observable variability And there is no inclusion of immunological status And it gives importance of extra capsular spread So this N2 that is bilateral involvement Implies better prognosis than N3 Where the large nodes greater than 6 centimeter So that is a limitation And this TNM staging This current TNM staging which relies on morphology of the tumor That is anatomical site and extent of disease With little or no attention given to the patient factors So patient factors is least considering this TNM staging And so it is helpful Definitely it is a helpful method It can give an idea about the therapy its prognosis And sharing of information between health centers is also very helpful Though it is having many shortcomings So that is all about TNM staging of oral cancer So I will come up with a new topic in 10 days TNM Thank you