Tumor markers for cancer detection

Tumor markers for cancer detection

Definition:Tumour markers are substances that can be detected in higher than normal amounts in the blood or serum ,urine, nipple ,aspirate fluid or stool and tissues of patients with certain types of cancer

How tumor markers produced

Tumors markers are produced either by the cancer cells themselves or by the body as a response to the cancer which can be detect by immunohistochemistery

 These tumor markers can be present also in some benign diseases

What are the aim of tumour markers
tumour markers are useful in diagnosis, staging ,treatment and detection of recurrence of cancers
Over the past decade, there has been an especially large interest
in identifying tissue tumor markers that can be used as prognostic or predictive markers. Although the terms prognostic marker and predictive marker are sometimes used interchangeably, the term prognostic marker usually is used to describe molecular markers that predict disease-free survival, disease-specific survival. and overall survival, while the term predictive marker is often used in the context of predicting response to certain therapies

The goal is to identify prognostic markers that can give informa­tion on prognosis independent of other clinical characteristics, and therefore can provide information in addition to what can be pro­jected on the basis of clinical presentation

This could allow us to further classify patients as being at higher or lower risk within clin­ical subgroups and to identify patients who may benefit most from adjuvant therapy. Ideally, prognostic tumor markers would be able to help determine which group of patients with node-negative breast cancer is at higher risk of relapse and thus provide adjuvant systemic therapy only to that group. regarding potential prognostic tumor markers for breast cancer
What are the predictive markers

Predictive tumor markers 

 Are markers that can prospectively identify patients who will benefit from a certain therapy. Some of the best predictive markers are estrogen receptor and HER2|neu. which can identify patients who can benefit from antiestrogen therapies (e.g. tamoxifen) and anti-HER|neu therapies (e.g. trastuzumab), respectively

 There is increasing interest in identifying predictive markers for chemotherapy so that patients can be given the reg­imens they are most likely to benefit from, while those who are most likely to benefit from existing conventional therapies can be spared the toxicity of the therapy and be offered investigational therapies

Examples for serum tumour markers as follow

PSA prostate specific antigen

• A prostatic epithelial protein

• Elevated if> 4 ng/dl, in general

• Used in conjunction with digital rectal examination, transrectal sonography needle biopsy for screening diagnosis and monitoring of treatment of prostatic cancer

• It is also elevated in benign prostatic hyperplasia, prostatitis, prostatic urinary retention, instrumentation and even ejaculation

• Thought not to rise significantly following rectal examination

• PSA velocity measures rate of change of PSA with time (> 0.7ng|dl suggessts malignancy

• PSA density compares PSA value with volume of prostate (> 0.15 suggests malignancy

• Age-related PSA (older patients have a higher normal cut-off

• Free-total PSA ratio 25% suggests malignancy

PSA is normally present in low concentrations in the blood of all adult males

CEA carcinoembryonic antigen

Is a glycoprotien found in the embryonic endodermal epithelium
 
An oncofetal antigen, normal, expressed in ermbryonic gut, liver, pancreas

Elevated in colorecral carcinoma In 60-90% of cases

may also be elevated in ovarian and breast carcinoma

also occasionally elevated In cirrhosis,alcoholic hepatitis.  inflammatory bowel disease,pancreatitis
Not specific or sensitive enough to be used as a screening tool

 Used to monitor efficacy of therapy and detection of recurrence

Alpha fetoprotein alpha-FP

Is glycoprotein normally produced by a developing fetus
AFP level decrease soon after birth to around 10 ng|ml in healthy adults

An embryonic antigen

Elevated in carcinoma of liver (also in cirrhosis, chronic hepatitis, normal pregnancy, fetal neural tube defects

Also elevated in non-seminomatous germ cell tumours of the testes NSGCT
AFP  is considered to be sensitive and specific enough to be used for screening for hepatocellular carcinoma
in higher risk populations 
 
Can be used for screening healthy hepatitis B  virus with annual or semi annual AFP levels and to screen
carriers with cirrhosis or chronic hepatitis and patient with cirrhosis of any etiology with twice yearly AFP
and liver ultrasound

Human chorionic gonadotrophin beta-hCG

A hormone
Elevated in pregnancy
Elevated in choriocarcinoma, non-small cell germ cell tumour (NSGCT) and in 7%
of seminomas where syncytiotrophoblastic elements are present

CAantigens CA-125 for non-mucinous ovarian cancers. A high concentration is more likely to associated
with malignancy. Can be used to monitor therapy. Can be raised in other conditions (eg pancreatitis
endometriosis, breast and pancreatic carcinomas
 CA-15-3 a glycoprotein, occasionally elevated in breast carcinoma
  CA-19-9 a glycoprotein sometimes elevated in pancreatic and advanced colorectal carcinoma

Thyroglobulin elevated in some thyroid carcinoma
 
Calcitonin elevated in medullary thyroid carcinoma
 

 ACTH and ADH are elevated in some lung carcinomas

lactate dehydrogenase cancer type germ cell tumours

Immunogobulins cancer type multiple myeloma and

waldenstrom macroglobulinema can be present in blood and

urine(Bence Jones protein) in urine

Fibrin and fibrinogen cancer type bladder cancer present in urine
HE4  ovarian cancer
HER2|NEU cancer types are breast gastric oesophageal cancer
Estrogen receptor (ER) Progestrone receptor (PR) in breast
 
Cancer tissue analyzed the tumour itself

CD20  non hodgkin lymphoma

tags:markers,tumor,cancer,immunohistochemistery

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