Cancer: Causes, Types, and Diagnostic Techniques

1. AMA 181 - Anatomy & Physiology/Medical Terminology/Pathology 12 Specialty Topics

2. Cancer Medicine (Oncology) • Cancer: A disease caused by abnormal and excessive growth of body cells; may occur in any tissue at any time, but more frequently in older individuals. • Malignant Tumors: accumulated cancer cells that grow in the body; compress, invade and destroy surrounding normal tissue. Cancer cells can also spread (metastasize) throughout the body via the bloodstream or lymphatic vessels. • Women: most common are lung, breast and colorectal cancers. • Men: most common are lung, colorectal and prostate cancers

3. Tumors • Also called neoplasms • Benign: grow slowly, encapsulated, do not usually spread, cells are differentiated (resemble the tissue from which they come) • Malignant: grow rapidly, invasive and infiltrative, spread into surrounding tissues, cells are undifferentiated (do not resemble surrounding tissue), vary in size and shape, piling on top of each other in a disorganized fashion and can break off and travel to other parts of the body.

5. Causes • Not fully understood, results from damage to genetic material (DNA) causing chemical changes in the DNA. • Environmental: chemicals in products and drugs such as cigarettes, car exhaust, hormones, etc... Radiation from sunlight, x-rays or other substances and even some viruses can cause cancer. • Heredity: susceptibility to some forms of cancer is transmitted to children via defects in the DNA of the egg or sperm cells. Genetic screening via blood testing can detect whether a person has inherited a cancer-causing gene.

8. Classification or Types • Carcinomas: largest group, solid tumors derived from epithelial tissue both internal and external such as skin, glands, digestive and reproductive organs (adenomas) • Sarcomas: less common, derive from connective tissue such as bones, muscles, fat and bone marrow. • Mixed-tissue tumors: derived from both types of tissues, least common and can be found in kidneys, ovaries and testes.

9. Treatments: major approaches • Surgery: invasive removal of tumor and possibly surrounding tissue • Radiation therapy: ionizing radiation delivered to cancerous tissue • Chemotherapy: drugs given to patient, standard treatment, often combined with other treatments • Biological therapy: use of body’s own defenses to fight tumor cells

12. Radiology • Radiology: medical specialty for the study of x-rays. • Wilhelm Roentgen discovered x-rays, they are named after him. • Radioactive Substances: materials that emit high-speed particles and energy-containing rays from matter. Three types: alpha particles, beta particles and gamma rays. Gamma rays are used to diagnose the path and uptake of chemical substances in the body.

13. X-ray Characteristics • Cause exposure of photographic plate by turning the areas of exposure black. • Able to penetrate different substances; pass through soft tissue (radiolucent) and are absorbed by dense tissue (radiopaque). Bones are radiopaque, areas surrounding are radiolucent, thus the x-rays are absorbed by the bones which show up white and pass through other tissue, showing up black on the plate enabling a good visual of bone tissues in the body. • Travel in straight lines allowing for precision images and ionization of cancer cells. • Ionization properties: can help destroy cancer cells but also can destroy good cells. Proper protection required during use.

15. Nuclear Medicine • Medical specialty that studies the characteristics and uses of radioactive substances in the diagnosis of disease. • Contrast Studies: natural differences in body tissue density cause contrasting shadow images on x-rays but can be hard to differentiate. A contrast medium is injected into the structure or fluid to help with visualization. Double contrast combines both radiopaque and radiolucent contrast mediums. • Barium is used for GI studies • Iodine is used for blood vessels and heart as well as other organs. Can be mixed with air for joints

16. Diagnostic Techniques • Computed Tomography (CT): beams x-rays at multiple angles through a section of the body creating multiple, cross-sectional views. Sensitivity or accuracy increased by use of iodine contrast agents that outline blood vessels. • Fluoroscopy: x-ray procedure that uses an image intensifier rather than a photographic plate, thus allowing for visualization of internal organs in motion, often used to guide surgery.

19. Diagnostic Techniques • Ultrasound: uses high-frequency sound waves that bounce off body tissues and are then recorded. Used for many organs and vessels of the body, but mostly recognized in fetal examination. Advantage is that it is non-invasive and does not harm tissues. Movement can be viewed and is often used to guide surgeries. • Magnetic Resonance Imaging (MRI): uses electromagnetic energy producing multiple views of the body. Can be used with or without contrast and is excellent for soft tissue imaging. Patients cannot have metal implants or pacemakers. • Study the various nuclear medicine tests and procedures in your text as well as the x-ray positioning.

25. Pharmacology Study of the preparation, properties, uses and actions of drugs. • Drugs (Medicines): used to prevent or treat a condition or disease. Can come from plants, animals or are synthesized (chemically made) in a laboratory. • Medicinal chemistry: study of new drug synthesis and relationship between chemical structure and biological effects • Pharmacodynamics: study of drug effects in the body: absorption, distribution, metabolism and excretion. • Pharmacokinetics: mathematical description of drug appearance and disappearance in the body over time • Molecular pharmacology: study of drug interaction with DNA, RNA and enzymes • Chemotherapy: study of drugs that destroy cancer • Toxicology: study of harmful effects of drugs and chemicals on the body Study the names, standards and references of drugs as well as the administration, toxicity and drug classes in your text; these are critical to know and understand.

26. Psychiatry • Branch of medicine that deals with the diagnosis, treatment and prevention of mental illness. Causes of mental illness are complex and may include psychological and social issues and/or chemical or structural issues. • Clinical Symptoms: abnormalities a mental health professional may find as evidence to mental health disorders. There are many psychiatric disorders, study them thoroughly in your text.

27. Therapeutic Techniques Techniques used to treat psychiatric disorders Major therapies: • Psychotherapy: treatment of emotional problems using psychological techniques • Electroconvulsive Therapy: use of electric current applied to brain to produce changes in brain wave patterns • Drug Therapy: use of drugs to treat such as antidepressants; there are many in your text, study them all.