23.1 Introduction:

Uncontrolled division of cells with a solid or fluid filled lesion is called a tumor which in malignant state invades neighbouring tissues and spreads to other parts of the body causing cancer. Benign tumors are restricted to a location. They do not show uncontrolled division and are not involved in invading neighbouring tissues.

Some of the common cancers include urinary b ladder cancer, bone cancer, brain cancer, breast cancer, cervical cancer, colon cancer, head & neck cancer, liver cancer, lung cancer, lymphoma, pancreatic cancer, prostate cancer, skin cancer, stomach cancer, ovarian cancer etc.

Classification of cancer on the basis of their origin

• • Carcinoma: Cancers that arise from epithelial cells. Eg: cancers of breast, colon, prostate, pancreas etc.

• Sarcoma: Cancers that arise from the connective tissue. Eg: bone sarcoma, hemangiosarcoma etc.

•  Lymphoma & Leukemia: Cancers that arise from hematopoietic (blood forming) cells.

• Germ cell tumors: Cancers derived from pluripotent cells, most often presenting in the testicle (seminoma) & the ovary (dysgerminoma).

•  Blastoma: Cancers derived from immature "precursor" cells or embryonic tissue. Eg: Retinoblastoma

•  Adenoma: Benign tumor of glandular origin.

•  Adenocarcinoma: Malignant adenoma.