The cancer comprises a group of malignant disease,characterised by abnormal irregular growth of the cells of involved parts.
Recent statistical data showed significantly increased morbidity and mortality of cancer,specially of some sites of the body.This increasement can be explained by more exposure to risk factors of uncontrolled modernization for exemple pollution of the environment with carcinogens and increasingly used food additives:used for coloration,taste and odour or for preservation of food.The changes of lifestyle and extensive industrialization represents a risk of cancer too.
Causes of Cancer:
Defined causes of cancer are not fully known yet.Epidemiologic and experimental studies,however,have revealed many factors with etiologic causal role or risk role.They are classified into environmental and genetic factors.
1.Genetic factors;
-abnormal gene in retinoblastoma
-genetic disorders as Down's Syndrome,late appearance of malignancy as leukaemia.
2.Environment factors:
-physical factors:exposure to radiation(in medicine,industry,atomic explosions,exposer to ultraviolets rays of sun) is the basic causal agent.
-chemical factor:many chemicals are carcinogenic.the exposure can be personal,by environment and occupational.The persoanl exposure is related to the lifestyle,diet,smoking cigarettes,drinking alcohol,the environment exposure through pollution(air,food,water,food) and occupational exposure usually industrial.
3.Biological factors:
-some infection agents;herpes virus of genital tract,virus B and C of hepatitis.
-bacteria flora of intestine:metabolic activity may change some chemicals in food into carcinogens that predisposed to cancer colon.
Host factors of Cancer are;
1.Age-in general malignant disease affects older ages,usually over 40 years.Younger age however,even early in childhood,may be affected according to inherentance,living circumstances and exposure to risk factors.
2.Sex-primary cancer of nosexual sites shows higer male mortality,in general cancer of respiratory tract.cancer of thyroid and biliary passages show higher female mortality.
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