Cancer Classification

NewsGuard 100/100 Score

Cancers may be classified by their primary site of origin or by their histological or tissue types.

Classification by site of origin

By primary site of origin, cancers may be of specific types like breast cancer, lung cancer, prostate cancer, liver cancer renal cell carcinoma (kidney cancer), oral cancer, brain cancer etc.

Classification by tissue types

The international standard for the classification and nomenclature of histologies is the International Classification of Diseases for Oncology, Third Edition (ICD-O-3). This classification is based on the ICD-O-3.

Based on tissue types cancers may be classified into six major categories:

1. Carcinoma

This type of cancer originates from the epithelial layer of cells that form the lining of external parts of the body or the internal linings of organs within the body.

Carcinomas, malignancies of epithelial tissue, account for 80 to 90 percent of all cancer cases since epithelial tissues are most abundantly found in the body from being present in the skin to the covering and lining of organs and internal passageways, such as the gastrointestinal tract.

Carcinomas usually affect organs or glands capable of secretion including breast, lungs, bladder, colon and prostate.

Carcinomas are of two types – adenocarcinoma and squamous cell carcinoma. Adenocarcinoma develops in an organ or gland and squamous cell carcinoma originates in squamous epithelium. Adenocarcinomas may affect mucus membranes and are first seen as a thickened plaque-like white mucosa. These are rapidly spreading cancers.

2. Sarcoma

These cancers originate in connective and supportive tissues including muscles, bones, cartilage and fat. Bone cancer is one of the sarcomas termed osteosarcoma. It affects the young most commonly. Sarcomas appear like the tissue in which they grow.

Other examples include chondrosarcoma (of the cartilage), leiomyosarcoma (smooth muscles), rhabdomyosarcoma (skeletal muscles), Mesothelial sarcoma or mesothelioma (membranous lining of body cavities), Fibrosarcoma (fibrous tissue), Angiosarcoma or hemangioendothelioma (blood vessels), Liposarcoma (adipose or fatty tissue), Glioma or astrocytoma (neurogenic connective tissue found in the brain), Myxosarcoma (primitive embryonic connective tissue) and Mesenchymous or mixed mesodermal tumor (mixed connective tissue types).

3. Myeloma

These originate in the plasma cells of bone marrow. Plasma cells are capable of producing various antibodies in response to infections. Myeloma is a type of blood cancer.

4. Leukemia

This a group of cancers that are grouped within blood cancers. These cancers affect the bone marrow which is the site for blood cell production. When cancerous, the bone marrow begins to produce excessive immature white blood cells that fail to perform their usual actions and the patient is often prone to infection.

Types of leukemia include:

  • Acute myelocytic leukemia (AML) – these are malignancy of the myeloid and granulocytic white blood cell series seen in childhood.
  • Chronic myelocytic leukemia (CML) – this is seen in adulthood.
  • Acute Lymphatic, lymphocytic, or lymphoblastic leukemia (ALL) – these are malignancy of the lymphoid and lymphocytic blood cell series seen in childhood and young adults.
  • Chronic Lymphatic, lymphocytic, or lymphoblastic leukemia (CLL) – this is seen in the elderly.
  • Polycythemia vera or erythremia – this is cancer of various blood cell products with a predominance of red blood cells.

5. Lymphoma

These are cancers of the lymphatic system. Unlike the leukemias, which affect the blood and are called “liquid cancers”, lymphomas are “solid cancers”. These may affect lymph nodes at specific sites like stomach, brain, intestines etc. These lymphomas are referred to as extranodal lymphomas.

Lymphomas may be of two types – Hodgkin’s lymphoma and Non-Hodgkin’s lymphomas. In Hodgkin lymphoma there is characteristic presence of Reed-Sternberg cells in the tissue samples which are not present in Non-Hodgkin lymphoma.

6. Mixed types

These have two or more components of the cancer. Some of the examples include mixed mesodermal tumor, carcinosarcoma, adenosquamous carcinoma and teratocarcinoma. Blastomas are another type that involves embryonic tissues.

Classification by grade

Cancers can also be classified according to grade. The abnormality of the cells with respect to surrounding normal tissues determines the grade of the cancer. Increasing abnormality increases the grade, from 1–4.

Cells that are well differentiated closely resemble normal specialized cells and belong to low grade tumors. Cells that are undifferentiated are highly abnormal with respect to surrounding tissues. These are high grade tumors.

  • Grade 1 – well differentiated cells with slight abnormality
  • Grade 2 – cells are moderately differentiated and slightly more abnormal
  • Grade 3 – cells are poorly differentiated and very abnormal
  • Grade 4 – cells are immature and primitive and undifferentiated

Classification by stage

Cancers are also classified individually according to their stage. There are several types of staging methods. The most commonly used method uses classification in terms of tumor size (T), the degree of regional spread or node involvement (N), and distant metastasis (M). This is called the TNM staging.

For example, T0 signifies no evidence of tumor, T 1 to 4 signifies increasing tumor size and involvement and Tis signifies carcinoma in situ or limited to surface cells. Similarly N0 signifies no nodal involvement and N 1 to 4 signifies increasing degrees of lymph node involvement. Nx signifies that node involvement cannot be assessed. Metastasis is further classified into two – M0 signifies no evidence of distant spread while M1 signifies evidence of distant spread.

Stages may be divided according to the TNM staging classification. Stage 0 indicates cancer being in situ or limited to surface cells while stage I indicates cancer being limited to the tissue of origin. Stage II indicates limited local spread, Stage II indicates extensive local and regional spread while stage IV is advanced cancer with distant spread and metastasis.



Further Reading

Last Updated: Jul 5, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Mandal, Ananya. (2023, July 05). Cancer Classification. News-Medical. Retrieved on May 25, 2024 from

  • MLA

    Mandal, Ananya. "Cancer Classification". News-Medical. 25 May 2024. <>.

  • Chicago

    Mandal, Ananya. "Cancer Classification". News-Medical. (accessed May 25, 2024).

  • Harvard

    Mandal, Ananya. 2023. Cancer Classification. News-Medical, viewed 25 May 2024,


  1. Vadim Shapoval Vadim Shapoval Ukraine says:

    New cancer classification system may revolutionize diagnoses and treatments. Cancers may be classified by their primary site of origin or by their histological or tissue types or even by their genetic and molecular types. Human cancer classification is currently based on the idea of cell of origin, light and electron microscopic attributes of the cancer. Recent innovative techniques in biology have provided a wealth of information on iron-metabolism-changes in cancerous cells. Future cancer treatment may be advanced by using an iron model of cancer classification. Cancer encompasses a class of heterogeneous diseases that differ on a cellular and molecular level - even within subtype. Rather than gradually collecting many tiny mutations, cancerous cells can dramatically acquire macromutations (large genomic leaps, tens or even hundreds of structural rearrangements in genomic regions). The mechanisms of chromothripsis (chromosome shattering) are not well understood if microbiological information (cancer occurs when cellular iron overload affects DNA, RNA, chromosomes, even mitoses) is ignored. If cancer encompasses a class of local/regional iron-overload diseases (pancreatic cancer - local iron overload in the cells in the pancreas; lung cancer - local iron overload in the cells in the lung), most cancers can be adequately treated with surgical procedures and iron-chelating therapies (direct intratumoral injections of antiiron agents, blood donation and iron-poor diet).

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
New study reveals how genes can alter the cancer-fighting power of fruits and fiber