Tumor grading

What does tumor grading mean? 

The World Health Organization (WHO) has created a standard by which all tumors are classified. There are over 120 brain tumor classifications defined by the WHO, based on the tumor cell type and location, making this a very complex diagnosis. Tumors are given a name based on the cells where they arise, and a number ranging from 1–4, usually represented by Roman numerals I-IV. This number is called the “grade” and it represents how fast the cells can grow and are likely to spread. Tumor grade is the description of a tumor based on how abnormal the tumor cells and the tumor tissue look under a microscope. This is critical information for planning treatment and predicting outcomes.  [1], [2], [11]

How tumor grade is determined

 If a tumor is suspected to be malignant, a doctor removes a sample of tissue or the entire tumor in a procedure called a biopsy. A pathologist then examines the tissue to determine whether the tumor is benign or malignant. The pathologist can also determine the tumor grade and identify other characteristics of the tumor cells. Based on the microscopic appearance of cancer cells, pathologists commonly describe tumor grade by four degrees of severity: Grades 1, 2, 3, and 4. Tumor grades are divided into two groups:  [1], [3], [4]

• Lower grade tumors 

  Lower grade tumors which include grades I & II are not very aggressive and are usually associated with long-term survival.

• Higher grade tumors

  This kind of tumors include grade III & IV and grow more quickly, can cause more damage, and are often more difficult to treat. These are considered malignant or cancerous.  

If a grading system for a tumor type is not specified, the following system is generally used:  [2], [6]

• G1:Grade 1 Tumor 

  Grade 1 Tumor  are the least malignant tumors and are usually associated with long-term survival. They grow slowly and have an almost normal appearance when viewed through a microscope and they are usually not cancer. Surgery alone may be an effective treatment for this grade tumor. Pilocytic astrocytoma, craniopharnygioma, and many tumors of neurons—gangliocytoma and ganglioglioma, for instance, are examples of grade I tumors. [5]

  Astrocytoma Grade 1          

   [7]
  

• G2:Grade 2 Tumor

  These tumors are slow-growing and look slightly abnormal under a microscope. Some can spread into nearby normal tissue and recur, sometimes as a higher grade tumor.  [5]
  

  Astrocytoma Grade 2

   [8]
  

• G3:Grade 3 Tumor

  These tumors are, by definition, malignant although there is not always a big difference between grade II and grade III tumors. The cells of a grade III tumor have an abnormal appearance under a microscope and are actively reproducing abnormal cells, which grow into nearby normal brain tissue. These tumors tend to recur, often as a grade IV. [5]

  Astrocytoma Grade 3

   [9]
  

• G4:Grade 4 Tumor

  These are the most malignant tumors. They reproduce rapidly, can have a bizarre appearance when viewed under the microscope, and easily grow into nearby normal brain tissue. These tumors form new blood vessels so they can maintain their rapid growth. They also have areas of dead cells in their centers. The glioblastoma multiforme is the most common example of a grade IV tumor. [5]
   

  Astrocytoma Grade 4

   [10]
  

Bibliography  

1. http://abc2.org/sites/default/files/Frankly%20Speaking%20About%20Cancer_Brain%20Tumors_0.pdf
2.  https://www.cancer.gov/about-cancer/diagnosis-staging/prognosis/tumor-grade-fact-sheet
3.  http://abc2.org/guidance/brain-cancer-facts/tumor-grades-and-types
4.  http://www.cancercenter.com/brain-cancer/grading/
5. http://www.abta.org/brain-tumor-information/diagnosis/grading-staging.html
6. https://www.cancertreatmentwatch.org/general/grading.shtml
7. http://www.keywordsuggests.com/vRsXqyScyl%7CK4BkhO45m*KBYhG7k%7CvA8HD5E1Dikf30/
8. http://www.keywordsuggests.com/ln2pHASqwFtoujtZXTM7%7CS6mAUzy58p1nrUWM4aDEFs/
9. http://www.keywordsuggests.com/gSvRehL18l7*ga6RwUHgBVMt6tt65msTk8LJv0wxKVlrBHwZoUqPL3xQFRZrUiFVdKnthWdFjScKp76jMwtwSQ/
10. http://www.keywordsuggests.com/zkoiDgxYmuJvtAqDCE9okQ80kVppuJZi8inI6joz6%7C5rBHwZoUqPL3xQFRZrUiFVdKnthWdFjScKp76jMwtwSQ/  
11. http://www.abta.org/brain-tumor-information/types-of-tumors/?referrer=http:/www.abta.org/brain-tumor-information/diagnosis/grading-staging.html?referrer=https:/www.google.de/