Characteristics of Tumors (Neoplasms)

BENIGN - slowly growing, encapsulated and noninvasive, well-differentiated, and non metastatic.

MALIGNANT - Rapidly multiplying, invasive & infiltrative, anaplastic & undifferentiated, and metastatic.

What Causes Cancer?

Malignant transformation results from damage to the genetic material, or DNA (deoxyribonucleic acid), of the cell.

Environmental Carcinogens

Chemicals:

• asbestos in insulation

• Dyes and industrial chemicals

• Hormones

• Hydrocarbons

• Insecticides

Radiation:

• sunlight (ultraviolet rays)

• x-rays

• Radioactive substances

Viruses:

• Human T cell leukemia virus (HTLV1)

• Human papilloma virus (HPV)

• Hepatitis B and C viruses

Oncogenes

Pieces of normal DNA that, when activated by a mutation, can convert a normal cell to a cancerous cell.

Heredity

Cancer may also be caused by transmission of DNA mutations that are associated with cancer susceptibility.

CLASSIFICATION OF CANCEROUS TUMORS

Carcinomas: The largest group, solid tumors that are derived from epithelial tissue that lines external and internal body surfaces, including skin, glands, and digestive, urinary, and reproductive organs.

Sarcomas: Malignant tumors but are less common than carcinomas. They derive from connective tissues in the body, such as bone, fat, muscle, cartilage, and bone marrow and from cells of the lymphatic system.

Mixed-Tissue Tumors: Derived from tissue that is capable of differentiating into both epithelial and connective tissue.

Examples:

kidney - Wilms tumor (embryonal adenosarcoma)

Ovaries and testes - Teratoma Germ cell tumor