Q.What is a carcinogen? Name one chemical carcinogen with its target tissue.

Cancer arises from abnormal, uncontrolled cell division forming a tumor/neoplasm (except leukaemia). A benign tumor stays localised, encapsulated and slow-growing (though it can still be dangerous, e.g. a brain tumor, and can sometimes turn malignant); a malignant tumor (true cancer) grows rapidly, invades surrounding tissue, and spreads via blood/lymph to form secondary tumors — metastasis.

Five types, named by tissue of origin: carcinoma (epithelial tissue — breast, lung, skin, stomach), sarcoma (connective tissue — bone/osteosarcoma, muscle/myosarcoma, cartilage/chondrosarcoma, fat/liposarcoma), lymphoma (lymphatic tissue), leukaemia (blood cancer — excess abnormal WBCs in bone marrow) and adenocarcinoma (glandular tissue — thyroid, pituitary, adrenal). …