What are disorders of growth due to?
- Abnormalities in regulations of cell size -> reduction in tissue mass
- Cell proliferation -> increases in tissue mass
- Differentiation resulting in abnormality of tissue mass/function/morphological appearance -> changes in tissue mass
What are the 3 types of reduction in tissue mass?
Agenesis - congenital absence (unilateral renal agenesis)
Hypoplasia - congenital reduction in size (testes in Klinefeleters)
Atrophy - shrinkage due to decreased size of cells (disuse)
What are the 3 types of increases in tissue mass?
Hyperplasia - increase in number of cells
Hypertrophy of cells - increase in size of cells (permanent cells cannot increase cell number)
Hypertrophy of parts - increase in size (may be hyperplastic or hypertrophic)
What are the 2 changes in tissue mass?
Metaplasia - change in type of mature tissue
Dysplasia - partial transformation to malignancy
What kind of change is columnar epithelium -> stratified squamous in smokers?
Metaplasia (endothelium -> endothelial type of adjacent tissue)
Are metaplasias reversible? Malignant?
- Benign and generally reversible
- Some types carry increased risk of malignancy (may be due to acquired genetic abnormalities, or due to irritant stimuli + tissue damage)
Are dysplasias malignant?
Genetic alteration to cell w/ loss of tumor supressor genes (and/or activation of oncogenes) but NOT sufficient for malignancy
- May occur w/ increase in tissue mass, or may be associated w/ microscopic lesion
What is the extreme end of dysplasia?
Carcinoma in situ
Identify the type of disorder of growth
- Mild dysplasia
- Carcinoma in situ (severe dysplasia)
- Cancer (invasive)
What does neoplasm literally mean?
- Abnormal mass of tissue that results when cells divide more than they should/do not die when they should
- Also called a tumor
Are neoplasms benign or malignant?
May be both
- Benign neoplasia = loss of control -> stable, non-spreading mass
- Malignant neoplasia = more control loss -> expansion, infiltration, metastasis
What is severe displasia?
Flat neoplastic change that is typically precancerous
What is a tumor?
Neoplastic mass of cells (benign/malignant)
What is cancer?
- Latin "crab" - seize upon adjacent tissues w/ pincher-like outgrowths
- Does not describe biological behavior (slow growing/indolent v. spread rapidly to many parts of body/rapidly cause death)
What are the 2 mechanisms by which cancer is capable of spreading throughout the body?
- Invasion - direct migration/penetration by cancer cells into neighboring tissues
- Metastasis - penetration into lymphatic/blood vessels -> circulate throughout bloodstream -> invade normal tissues elsewhere in body
Who was the 1st to recognize that cancer (and all disease) was a cellular disorder and it could be dx'd at microscopic level based on cellular appearance/arrangement?
How are cancer cells clonal?
All cancerous cells in a tumor are derived from a single cell
- Single cell -> cancerous cell occurs in steps w/ each step governed by a mutation
- Several subclones may appear before one that has cancerous characteristics
What are characteristics of a benign neoplasm?
- Well-defined margins of tumor (encapsulated)
- Neoplastic cells grow only locally
- Slow rate of growth, may cease
- Generally have good pronosis (lead only rarely to death)
What are characteristics of a malignant neoplasm?
- Poorly defined margins of tumor (infiltrative)
- Rapid rate of growth, progressive
- Neoplastic cells growing into and destroying surrounding tissue (morbidity)
- Major cause of death (mortality)
What does the incidence of each type of cancer vary according to?
Age, gender, social class, ethnic origin, geographical location
T or F: Most cancers are age related.
T; more yrs of cell divison, cancer evolves slowly due to prolonged exposure to environmental carcinogens
How is cancer distributed between genders?
Cancer used to be more common in females than males (b/c of freq of cervical and breast CA, and rarity of lung cancer) -> now reversed in most countries
- CAs that have higher incidence in females = gall bladder, thyroid, malignant melanoma of skin
What has been found in population studies of cancer incidence?
Cancers arise w/ diff frequencies in diff areas of the world
- Japan = stomach cancer
- US = colon cancer
- Australia = skin
- Japanese fams that move to US -> higher rate of colon cancer/lower rate of stomach cancer (NOT just heredity -> could involve cultural, behavioral, envir factors)
What is a low-strength type of radiation that can cause cancer?
Sunlight (UV radiation)
What is a high-strength form of radiation that can increase rates of cancer?
X-rays or radiation emitted from unstable atoms called radioisotopes
What are chemicals and radiation that are capable of triggering the development of cancer called?
Why do carcinogens have a "lag time"?
They act through a multistep process that initiates a series of genetic mutations and stimulates cells to proliferate (this requires a prolonged period of time)
- Young ppl exposed to carcinogens from smoking cigarettes generally don't develop cancer for 20-30 yrs
How do cancer viruses cause cells to become malignant?
Some of the viral genetic info carried in the nuclei acids is inserted into the chromosomes of the infected cell
- Viruses can't reproduce on their own, they enter into living cells -> infected cell to produce more copies of the virus (in this case more copies of the cancer)
People who develop AIDs after being infected w/ HIV are at high risk for developing what type of cancer?
Kaposi's sarcoma - malignant tumor of blood vessels located in the skin
- Not directly caused by HIV, but immune deficiency makes people more susceptible to viral infx called KSHV (Kaposi's sarcoma-associated herpes virus)
What bacteria has been associated w/ the development of cancer?
H. pylori (which causes stomach ulcers) -> increased risk for stomach cancer