Classification of Tumors

Tumors may be classified in a variety of ways depending upon:

a. Primary site of origin

b. Tissue types

c. Grade

d. Stage

Classification depending upon site of origin

Tumors may be classified into different types depending on the primary site of origin. These include:

1. Tumors of heart

2. Vascular Tumors

3. Lymphoid Neoplasms

4. Tumors of lung

5. Tumors of liver

6. Tumors of salivary glands

7. Tumors of urinary bladder

8. Testicular tumors

9. Ovarian neoplasms

10. Tumors of breast

11. Pituitary tumors

12. Thyroid tumors

13. Tumors of kidney

14. Tumors involving bones

15. Soft tissue tumors

16. Tumors of Central Nervous System

Classification depending upon tissue types

Depending upon the tissue types, we may classify cancers into six main categories:

1. Carcinomas

2. Sarcomas

3. Myelomas

4. Leukemias

5. Lymphomas

6. Mixed types

1. Carcinoma

The cancer which arises from the epithelial layer, either present on the external parts of the body or the internal lining of organs is known as carcinoma. Carcinomas form the most common variety of tumors.  These are commonly found in the breast, lungs, bladder, colon and prostate.

Carcinomas are further divided into two varieties:

a. Adenocarcinomas

Carcinomas that develop in an organ or gland constitute adenocarcinomas.

b. Squamous cell carcinomas

Carcinomas that originate from squamous epithelium constitute squamous cell carcinomas.

2. Sarcoma

The cancers which originate from the supporting tissues of the body i.e. connective tissue, muscles, bones, carilage and fat are known as sarcomas. Common examples of sarcomas include:

• Osteosarcoma in bones
• Chondrosarcoma of cartilage
• Leiomyosarcoma of smooth muscles
• Rhabdomyosarcoma of skeletal muscles
• Fibrosarcoma of fibrous tissue
• Angiosarcoma of blood vessels
• Liposarcoma of adipose tissue
• Astrocytoma of connective tissue in brain

3. Myeloma

The cancers which originate from plasma cells present in bone marrow constitute myelomas. These may be regarded as a type of blood cancers.

4. Leukemia

The cancers which affect bone marrow leading to excessive production of immature white blood cells constitute leukemias. These are also a variety of blood cancers. As white blood cells are involved in providing immunity, thus a person suffering from leukemias becomes prone to infections.

Leukemias may be classified into:

a. Acute lymphocytic, or lymphoblastic leukemia (ALL)

b. Chronic lymphocytic, or lymphoblastic leukemia (CLL)

c. Acute myelocytic leukemia (AML)

d. Chronic myelocytic leukemia (CML)

e. Polycythemia vera

5. Lymphoma

The cancers which originate in lymphatic system constitute lymphomas. These may affect lymph nodes as well.

Lymphomas may be divided into:

a. Hodgkin’s lymphomas

b. Non Hodgkin’s lymphomas

6. Mixed types

As the name indicates, these have more than one varieties. Common examples are:

Blastomas

Adenosquamous carcinomas

Teratocarcinomas

Classification depending upon Grade

Cancers may be classified into different varieties depending upon the grade. These include:

G1 -Well differentiated

G2 -Moderately differentiated

G3 -Poorly differentiated

G4 -Undifferentiated

For more information see grading of tumors.

Classification depending upon Stage

Cancers may also be classified depending upon the stage. the TMN classification is used.

T -tumor size

N -nodal spread

M -metastasis

For more information see staging of tumors.