Lecture # 43 NEOPLASIA - 4 Dr. Iram Sohail Assistant Professor Pathology College Of Medicine Majmaah University

OBJECTIVES Discuss epidemiology – Cancer incidence – Geographic & environmental variables – Age & heredity Discuss acquired pre-neoplastic disorders

Epidemiology Epidemiology is the study of causes, patterns and effect of health & disease condition in a defined population.

Cancer incidence

Geographic & environmental variables Environmental factors are the predominant cause of the most common cancers. Examples – Breast cancer is 4 to 5 folds more common in USA than Japan. – Stomach cancer incidence is seven times higher in Japan as compared to USA (because of dietary habits). – Liver cell carcinoma is more common in Africa.

Some occupational agents can also cause cancers.

Other common associations of cancer Cigarette smoking lung & oral cavity cancers Alcohol consumption liver cancer Cervical cancer very young age at first intercourse, multiple sex partners

Age In general, the incidence of cancer increases with age (55 – 75). But some cancers are more common in children.

Like – Leukemias – CNS tumors – Bone sarcomas – Soft tissue sarcomas – Lymphomas – Retinoblastoma – Wilms tumor

Heredity Most of the cancers have hereditary predisposition. Hereditary cancers are divided into 3 forms.

1.Inherited cancer syndromes In this type inheritance of a single mutant gene greatly increases the risk of cancer development. Example – Retinoblastoma – Osteogenic sarcoma

2.Familial cancers They run in families (familial) Carcinoma of ovary, breast, colon Features of familial cancers – Early onset of age – 2 or more close relatives involved by tumor – Bilateral or multiple tumors

3.Autosomal recessive syndromes of defective DNA repair Characterized by chromosomal or DNA instability Example – Xeroderma pigmentosa (Defective DNA repair)

Acquired pre-neoplastic disorders Pre-neoplastic disorders are certain diseases associated with an increased risk of developing cancer. Well recognized predisposition to malignant tumors

Examples 1.Persistent regenerative cell replication – Squamous cell carcinoma in a long unhealed skin wound – Hepatocellular carcinoma in cirrhosis of liver

2.Hyperplastic & dysplastic proliferation – Endometrial carcinoma in endometrial hyperplasia – Bronchogenic carcinoma in dysplastic bronchial mucosa of smokers – Colorectal carcinoma in ulcerative colitis Changing from benign to malignant is very rare.