patho sheet #15-Abdul hameed Akrabawe

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patho sheet #15-Abdul hameed Akrabawe

Post by Shadi Jarrar on 25/10/2010, 10:54 pm

بسم الله الرحمن الرحيم

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• Epidemiology of the cancer:
1-Geographic and Environmental Variables
• Environmental factors maybe chemical , radiation ..
• Environmental factors that give rise to somatic mutations are the predominant cause of the most common sporadic cancers
• Environmental Chemical carcinogens that cause cancer are lot like radiation , cigarette , sun light and alcohol consumption and also viruses like human pappilloma viruse that is common cause of cervical cancer
2- age : because of;
1- accumulation of somatic mutations
2- decline in immune competence
• note : leukemia is cancer of blood
• the most common forms of cancer are cancers in lung , breast and in colon


3- heredity : divided into
1- Inherited cancer syndromes (ICS)
• inheritance of a single mutant gene greatly increases the risk of developing a tumor.
• Mutation may take place in gens that control growth or in tumor suppressor gene (that break the cell cycle ) and we know that each gene has tow alleles
• The mutation in tumor suppressor gene happens if the tow alleles are mutated . but in inherited cancer syndrome the patient inherits one mutated allele of tumor suppressor gene so increase predisposition to cancer(autosomal dominant pattern of inheritance) . later on , the mutation will take place in the other gene so developed of cancer so cancer take place when their is tow mutant allels one is inherited and the other is from somatic mutation(in the case of ICS)
• Note : retinoblastoma : is malignant tumor of the eye result from mutation in tumor suppressor gene called retinoblastoma gene
• Approximately 40% of retinoblastomas are familial, they inherent mutant allele from their parents so increase predisposition to have cancer
• adenomatous polyposis means : multiple polyps in colon
• another example is Familial adenomatous polyposis : the patient has one mutant allele so will have colon adenoma and because of somatic mutation of other allele will develop carcinoma of the colon by age of 50
note : in the picture the polyposis of the colon to become Familial adenomatous polyposis the pationt must have 100 polyps in the colon

o patients with inherited cancer syndrome , they should have specific marker phenotype . for familiar adenomatous polyposis is polyp
o sporadically mean : cancer occure without inheritance of any mutant allele
o colon cancer maybe in the form of inherited cancer syndrome or in the form of familiar cancer
o remember that cancer of colon, breast, ovary, and brain occur sporadically not through inherited mutant alleles but some of them like colon cancer occur in both sporadic and inherited
o for example in familiar colon cancer , we do not see polyp (specific marker phenotype) in contrast to inherited one
o In general, siblings have a relative risk between 2 and 3 more common that general population in the case of familiar cancer
o Remember that the inherited causes of cancer are only 5-10% of the causes of cancer but the must imp. Cause are environmental factors
o In the Autosomal Recessive Syndromes of Defective DNA Repair the patient must inherit the tow mutant alleles to develop cancer
o Acquired : mean not inherited
o Acquired Preneoplastic Disorders : the name acquired is not accurate because the majority of disorders will not converted into cancer
o In 5% of patient with endometrial hyperplasia may develop endometrial cancer
o As the risk of dysplasia increase , the probability to cancer increase (as in cigarette individuals ) but remember that the risk is low
o Gastritis : inflammation of gastric mucosa
o The most commpn environmental cause of gastritis is Helicobacter pylori (bacteria)infection this will induce repair and regeneration of gastric mucosa and the inflamatory Cytokines ,that release, may cause somatic mutation inside gastric mucosa so , they will develop gastric carcinoma
o Leukoplakia : mean white badges in oral cavity
o Genetic damage of the cancer(mutation) must be nonlethal to prevent apoptosis
o the gens for growth factor , growth factor receptors , signal transuding proteins or for transcription factors called proto-oncogens
o normally, the stimulus for growth should be external , but in the case of cancer , the increase in growth take place without external stimulus as in liver regeneration : normally the remaining cells grow in response to restriction (external) but in case of cancer the growth due mutation .
o growth-inhibiting tumor suppressor genes : are breaks during cell cycle (not inhibit tumor)
o Carcinogenesis at phenotype level : growth of the mass then rapid growth of the mass then invasion and maybe end in metastasis ( multistep processes)
o Aggressive mean : if tumor does no metastasis probably, with time it becomes more potent metastasis
o Self-sufficiency in growth signals : occur when their is mutation in growth factor , G.F receptor or mutation in signal transuding proteins ...through mutation in proto-oncogen
o growth-inhibitory signals : tumor suppressor genes
o Evasion of apoptosis : through mutation in gene that cause apoptosis
o In any cancer , we can notice more than one of seven physiological causes of tumor
o In basal cell carcinoma : the tumor cells are able to invade but not able to metastasis so in the basal cell carcinoma , not all of the seven causes observed
o But in osteo sarcoma : the cells have the ability to metastasis so most or all of thesis features may present



The end…. GOD LUCK


 Done by : Abdullhameed Nawaf Mahmood.
 Lecture no. :15
 Date : 24/10/2010
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Shadi Jarrar
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عدد المساهمات : 997
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تاريخ التسجيل : 2009-08-28
العمر : 26
الموقع : Amman-Jordan

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