Med-Surg Immune System, part 9: Tumor Classification

by Cathy Parkes

In this article, we cover how to classify tumors, which is an important part of your knowledge on cancer in a Med-Surg or Critical Care class, exam, or floor! There are three ways to classify tumors: 

  1. Tissue type, which is the type of body tissue in which the cancer originates — and there are five main types of cancer.
  2. Grading, which is similarity of a cancer to its tissue of origin 
  3. Staging, which is the progression or extent of disease 

Cancer and tumor classification are covered in our Medical-Surgical flashcards (Immune system), and Cathy’s videos follow along with the cards.

Tissue type - The five types of cancer

The five main types of cancer you need to know about are:

  1. Carcinoma
  2. Sarcoma
  3. Leukemia
  4. Myeloma
  5. Lymphoma

Each of these types can be further broken up, and we cover some of those common sub-categorizations in the sections below. 

It’s important to note that the way we refer to cancers in everyday life (e.g., “lung cancer”, “cervical cancer”) can be somewhat broad, and all cases of these cancers do not necessarily fit cleanly into one category. This is because body parts can be made of multiple types of tissues. 

For example, some lung cancers are adenocarcinomas while some are squamous cell carcinomas. See the table below for more information.

Carcinoma

Carcinomas make up the majority of cancers, around 80-90%, and that’s because carcinomas originate in the epithelial tissue, and epithelial tissue is everywhere in your body. Epithelial tissue lines your body’s surfaces (e.g., skin), lines your body cavities (e.g., mouth), and makes up many of the glands and organs in your body. There are two main carcinomas to know about, adenocarcinomas and squamous cell carcinoma. 

Because carcinomas make up the majority of cancers, most of the cancers that we will cover in our immune system series are carcinomas.

Adenocarcinomas

Adenocarcinomas are cancers originating from glands (adeno = gland) that typically secrete substances, e.g., mucus, or breast milk. Lung cancer and breast cancer are cancers that are usually classified as adenocarcinomas.

Squamous cell carcinoma

Squamous cell carcinoma originates in the squamous epithelium, which is the layer of epithelial tissue that protects you, and can be found in the mouth, lips, and in the middle layers of the skin. The word squamous refers to the shape of the cells and means flat, or a greater width than height (which would be a flat shape).

The term “squamous cell carcinoma” is most commonly used to describe squamous cell carcinoma of the skin, which we cover in our video on skin cancer. However, squamous cell carcinoma can occur in the mouth, esophagus, lungs, or other places where squamous epithelial cells are found.

Sarcoma

Sarcomas are cancers that originate in the supportive or connective tissues of the body, including bones, muscle, tendon, cartilage and fat. Sarcomas are usually broadly grouped into bone-related and soft-tissue related sarcomas. Some examples of bone-related sarcomas that you should know about are osteosarcoma and chondrosarcoma. 

Confusingly, “Kaposi’s sarcoma” (which we briefly touched on in this series as a symptom of AIDS) is not considered a true sarcoma.

Osteosarcoma

Osteosarcoma is a cancer that originates in the bone. This is easy to deduce because the prefix osteo- means bone.

Chondrosarcoma

Chondrosarcoma is a cancer that originates in the body’s cartilage. This one is easy to decode if you know that the prefix chondro- means cartilage. We created our Medical Terminology flashcards to make breaking down words like chondrosarcoma into its parts easy, so you never have to be confused by an unfamiliar word on an exam!

Leukemia

Leukemia is a type of cancer that originates in the bone marrow. We cover leukemia in depth in our article on hematologic cancers

Myeloma

Myeloma is a type of cancer that originates in the plasma cells specifically, within the bone marrow. Both leukemia and myeloma happen in the bone marrow, but myeloma is exclusively the plasma cells. Check out our article on multiple myeloma for more depth on this subject.

Lymphoma

Lymphoma is a type of cancer that originates in the lymphatic glands or nodes, or in organs like the thymus or spleen that are part of the lymphatic system. Check out our article on Hodgkin’s vs. non-Hodgkin’s lymphoma for more information on lymphoma.

Common cancers with classifications

Cancer Location or Sub-type Tissue type classification Tissue type sub-classification
Skin cancer n/a Carcinoma Basal cell carcinoma
Skin cancer n/a Carcinoma Squamous cell carcinoma
Skin cancer Melanoma Outside the 5 categories n/a
Endometrial cancer Glandular cells of uterine lining Carcinoma Adenocarcinoma
Breast cancer Milk duct or glandular tissue of breast Carcinoma Adenocarcinoma
Lung cancer Lung glands that secrete mucus Carcinoma Adenocarcinoma (most common in nonsmokers)
Lung cancer Squamous cells of lung Carcinoma Squamous cell carcinoma (most common in smokers)
Cervical cancer Squamous cells of cervix (most cases) Carcinoma Squamous cell carcinoma
Cervical cancer Glandular cells of cervix (some cases) Carcinoma Adenocarcinoma
Ovarian cancer Epithelial cells of ovaries (most cases) Carcinoma Adenocarcinoma
Prostate cancer Glandular cells of prostate Carcinoma Adenocarcinoma (most common)
Colorectal cancer Glandular cells of the colon/rectum Carcinoma Adenocarcinoma
Leukemia n/a Leukemia n/a
Lymphoma n/a Lymphoma n/a
Multiple Myeloma n/a Myeloma n/a

Tumor grading

Tumor grading is another classification method whereby a tumor is compared to its tissue of origin and graded on a 1-4 scale. For example, if a tumor is found in the breast, the cells of that tumor will be compared to the cells of the surrounding breast tissue. 

A grade one tumor means the cancer is “well-differentiated” and resembles the tissue of origin. A grade four tumor means the cancer has no similarity at all to the tissue of origin, and looks like something else entirely.

A tumor’s grade is an indication of how fast it is likely to grow or spread. A grade one tumor is likely to grow and spread slowly. In contrast, a grade four tumor is likely to grow and spread quickly and poses a more immediate danger to the patient.

Tumor staging (TNM methodology)

You have likely heard something like “Stage 4 cancer” in the past. In this section, we will explain tumor staging, which is a little different than overall cancer staging. 

We stage tumors with a T, N, M scale, and then those results are combined with other factors that are specific to the cancer, to get the cancer stage. Tumor staging is used with cancers marked by solid tumors, and is not applicable to leukemia. 

T for tumor (T1 through T4)

The T in TNM staging is for tumor — pretty easy to remember! The T score refers to the size of the tumor, and can be T1, T2, T3, or T4. A t1 tumor would be a pretty small tumor, and a large tumor would rate a T4. 

We have to be vague here and use “small” and “large” because how small or large a tumor is is quite relative to the body part or organ that is impacted. For example, a T3 tumor of the breast is larger than 50mm, while a T3 tumor of melanoma is between 2-4mm.

T may also indicate location relative to other body part landmarks, rather than size. In prostate cancer, a T3 tumor means that the tumor has grown outside of the prostate.

N for node (N0 through N3)

N is for node and lymphatic system involvement. The N directly corresponds to the number of regional lymph nodes involved in the cancer. 

N0 means that no lymph nodes have been affected, N1 is one lymph node with cancer, N2 is two lymph nodes with cancer, etc.

M for metastasis (M0 or M1)

M is for metastasis, or spreading, and this can be thought of as a binary, because it is either 0 or 1. It may also be helpful to think of this as a boolean value, meaning it is either true or false. M0 means the cancer has not metastasized, and M1 means that the cancer has metastasized.

Putting it all together

Using this simple TNM staging system, there are at least (4 x 3 x 2) TNM 24 combinations, and for a certain type of cancer, these will be grouped into stages. Realistically, there can be more types than this as the tumors may be measured by other factors depending on the type of cancer. But, knowing what TNM staging is and how to break down the different scores that make up TNM stages will be helpful to you as you come across descriptions of tumors.

For example, if you see a tumor that is T4, N2, M0, you will know that it is a relatively large tumor, affecting two lymph nodes, but it has not metastasized. 

Cathy’s teaching on HIV/AIDS is intended to help prepare you for Medical-Surgical nursing exams. The Medical-Surgical Nursing video series is intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI and NCLEX.


Full Transcript

Hi. In this video, we are going to talk about tumor classification. Specifically, we will talk about tissue type as well as grading and staging of cancer. If you are following along with cards, I am on card number 20 in the Immune System of our Medical-Surgical Nursing 2nd Edition deck.

So when we are describing a type of cancer, we are typically referring to the type of tissue in which the cancer originates. And there are 5 main types of cancer that I would be familiar with.

The first are carcinomas. So carcinomas make up the majority of cancers, around 80 to 90%, and they originate in the epithelial tissue. So epithelial tissue, it lines your body surfaces, like the skin. It lines your body cavities, and it makes up many of the glands and organs in the body.

Within carcinomas, we have adenocarcinomas which are organs or glands that typically secrete substances such as mucus.

And then, we also have squamous cell carcinoma which originates in the squamous epithelium.

Alright. After carcinomas, we have sarcomas. So sarcomas are cancers that originate in the supportive or connective tissues of the body. So this can include bones, muscle, tendon, cartilage and fat. Some examples of sarcomas include osteosarcoma, so that is a cancer that originates in the bone, as well as chondrosarcoma, which is a cancer that originates in the cartilage.

Okay. Then we have leukemia. Leukemia is a type of cancer that originates in the bone marrow.

And then we have myeloma, and myeloma cancer originates in the plasma cells specifically, in the bone marrow.

And then lastly we have lymphoma. Lymphoma originates in the lymphatic glands or nodes, or in organs such as the thymus or spleen.

Now that we've identified the tissue type, we need to grade the cancer. So with grading, we are comparing the cancer to the tissue of origin, and we're giving it a grade of one, two, three or four.

Grade one means that the cancer is well differentiated and it resembles the tissue of origin, versus a four, which mean that the cancer has no similarity at all to the tissue of origin.

So a grade of one is definitely better, because a grade one cancer usually grows more slowly, versus a grade four cancer usually grows very quickly and spreads rapidly.

Alright. Let's talk about staging. So when we're staging cancer, we use the TNM staging methodology. So T stands for tumor, N stands for node, and M stands for metastasis.

So with T for tumor, we're going to have either a T1, T2, T3, or T4. And this is really given based on the size and extent of the tumor. So if it's a nice little small tumor, it gets T1. If it's a really big one, then it would get T4.

Then we have node, N for node. And this really corresponds to the number of regional lymph nodes involved in the cancer. So if the cancer has spread to the lymph nodes, this tells you the number of lymph nodes that are affected. So you can have N0, which means that no lymph nodes have been affected, but you can also have N1, N2, N3. So if you have N2, that means there are two lymph nodes where the cancer has spread and affected those lymph nodes.

And then lastly, we have metastasis. So we either have M0 or M1. M0 means we have no metastasis, so the cancer has not spread to other places in the body. And 1 means we do have metastasis to other places in the body.

Okay. So hopefully that's been helpful for you to understand the classification of tumors. In my next video, we will talk about nursing care and patient teaching regarding complications that occur with cancer treatment. Thank you so much for watching, and I'll see you on the next video!


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