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Tumor markers 1

Tumor markers 

DEFINITION  - Characteristic of ideal tumor markers  - Roles of tumor markers .



DEFINITION OF TUMOR MARKERS 
A tumor marker is a substance present in or  produced by a tumor or by the tumor's host in response to the tumor's presence that can be used to differentiate a tumor from normal issue or to determine the presence of a tumor based on measurements  in the blood or secretions . 
Such a substance can be found in cells , tissues , or body fluids . Tumors may secret a wide range of substances into blood including hormones , enzymes and tumor antigens , which are collectively referred to as tumor markers . 

Tumor markers can be used in a number of ways , including : 
1 -  Monitoring treatment and detecting recurrence of disease ( these are the most useful roles for tumor markers ) . 
2 - Diagnosis 
3 - Screening 
4 - prognosis 
It can be measured qualitative or quantitative by : 
Chemical , immunological , or molecular biological , methods to determine the presence of a cancer . 


Tumors are graded according to their degree of differentiation as : 
1 - Well differentiated 
2 - poorly differentiated 
3 - Ana plastic ( without form ) 


Tumor markers are the biochemical or immunological counter parts of the differentiation States of the tumor . 


Characteristic of ideal tumor markers
1 - Specificity  for cancer the substance should be produced only by the tumor . 
2 - Sensitivity for cancer : a vary small tumor growth will produced measurable amounts of markers . 
3 - The amount of marker produced will correlate well with the tumor load 
4 - The assay for the markers must be inexpensive , easy to perform, and sensitive.
5 - The half - life of marker must be short enough , so that when production drops , the level falls off rapidly . 



Roles of tumor markers
1 - Tumor markers have limited use in diagnosis . 
2 - Marker can be used to help make or confirm a diagnosis .
3- The primary use of tumor markers is to monitor therapy in patients in whom a malignant tumor has been diagnosed .
4 - Other markers may be measured to help determine prognosis . 



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