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Ch. 20 & 21: Neoplasms and Cancer & Congenital and Genetic Disorders
Terms in this set (52)
Second leading cause of death:
The study of tumors
Gross & microscopic characteristics are innocent, amenable to surgery, higher rate of survival
Collectively known as cancers, imply invasion and destruction and spread (metastasize)
-Cellular growth that no longer responds to normal genetic controls
-Cells continue to reproduce, without need for them to do so
-Deprives other cells of nutrition
What are the most common cancers in men?
Prostate cancer, Lung cancer, and Colorectal cancer
What are the most common cancers in women?
Breast cancer, Lung cancer, Colorectal cancer
The suffix -oma implies:
That the tumor is benign
Tumors that have the tissue name plus the suffix- carcinoma are:
Tumors of connective tissue that are often malignant
-Tumor comprised of cells from more than one germ layer
-Arise from totipotent cells (usually gonads)
-Benign cystic teratoma of ovary is the most common teratoma
What are the two types of aberrant differentiations?
Hamartoma and Choristoma
Disorganized mass of tissue whose cell types are indigenous to the site of the lesion
Ectopic focus of normal tissue (heterotopia)
The development of cancer
Describe the process of tumorigenesis:
-Cancer results from an uncontrolled proliferation of a single cell
-Tumorigenesis occurs by a cumulative progression of genetic alterations
-Cells become less responsive to growth regulation and better able to invade normal tissues
-First step is the formation of a benign tumor
-The sequence in which genes mutate influences the development of cancer
What are the four classes of normal regulatory genes (preventing)?
-Oncogenes and oncoproteins
-DNA repair genes
What are the tumor suppressor genes?
-Governors- mutation leads to transformation by removing the "brake" on cellular proliferation
-Guardians- sense genomic changes and choreograph "damage" control for cessation
What are the differences between benign and malignant tumors?
Benign- differentiated cells that reproduce at a higher rate than normal, encapsulated, tissue damage (a result of compression of adjacent structures; can be life threatening in the brain)
Malignant- undifferentiated, nonfunctional cells, rapid reproduction (abnormal mitotic figures), infiltrate or spread into surrounding tissue, spreads to distant sites
-Lack control of mitosis and do not undergo apoptosis
-No normal organization of differentiation
-No contact inhibition
-Abnormal cell membranes
-Altered surface antigens
-Do not adhere to each other; often break loose from mass and invade other tissues and may spread to distant sites
What are the effects of malignant tumors?
-Mass compresses blood vessels leading to necrosis and inflammation around tumor
-Tumor cells may secrete enzymes or hormones that break down proteins and cells and cause systemic effects, such as altered calcium levels
-Inflammation and loss of normal cells can lead to progressive reduction in organ integrity and function
-Angiogenesis; some tumors secrete growth factors to stimulate the development of new capillaries in the tumor
What are the warning signs of cancer?
1. Unusual bleeding or discharge anywhere in the body
2. Change in bowel or bladder habits (e.g. prolonged diarrhea or discomfort)
3. A change in a wart or mole
4. A sore that does not heal
5. Unexplained weight loss
6. Anemia or low hemoglobin, and persistent fatigue
7. Persistent cough or hoarseness without reason
8. A solid lump, often painless, in the breast or testes
What are the local effects of tumors?
-Pain: may be absent until very late stages, occurs when tumor is well advanced, severity depends on the type of tumor
-Obstruction: occurs when tumor compresses a duct or passageway, blood supply or lymphatic flow may be restricted, digestive tract, airflow in bronchi
-Tissue necrosis and ulceration: may lead to bleeding or infection around the tumor
What are the systemic effects of tumors?
-Weight loss and cachexia
-Effusions; inflammation causes fluid buildup in body cavities
-Paraneoplastic syndrome; associated with certain tumor types, tumor cells release substances that affect neurological function and may have hormonal effects
Local spread; tumor cells grow into adjacent tissues.
E.g. Uterine carcinoma invades the vagina
Spread to different sites via blood or lymph or other body fluids.
E.g. Carcinoma of the colon spreads to the liver
Most common staging system of cancer;
T- size of primary tumor
N- involvement of regional lymph nodes
M- spread/metastasis of tumor
Process whereby normal cells are transformed into cancer cells. The process varies greatly with respect to time. Cancer is thought to be a multifactoral disease because of: environmental effects, change in gene expression, infection
Stages of Carcinogenesis
1. Initiating factors- procarcinogens cause the first irreversible change in cellular DNA but does not create an active neoplasm
2. Exposure to promotors- includes hormones and environmental chemicals, cause further changes in DNA, less differentiation and increased rate of mitosis and/or lack of apoptosis, dysplasis or anaplasia, lead to tumor development
Risk Factors of Cancer:
1. Genetic Factors
5. Biological Factors
Disorders classified by inheritance patterns (Dominant, Recessive, or X-linked), single gene controls a specific function, may have systemic effects (E.g. cystic fibrosis, Tay-Sachs disease, phenylketonuria or PKU):
What are examples of single-gene disorders?
Autosomal dominant disorders, adult polycystic kidney disease, Huntington's chorea, Familial hypercholesterolemia, Marfan's Syndrome
Autosomal Recessive Disorders
Both parents must pass on the allele for disorder to occur; parents must be heterozygous and unaffected (they are termed carriers) or parents must be homozygous and affected.
The homozygous recessive child will have the disorder, while the heterozygous child will have no clinical sign of the disease but will be a carrier.
What are some examples of Autosomal Recessive Disorders?
PKU (lack of PAH)
Tay-Sachs Disease (lack Hexosaminidase A; HEXA gene, chromosome 15)
Sickle Cell Anemia
Autosomal Dominant Disorders
Inheritance of one allele causes disorder; only one parent needs to carry allele.
No carriers; unaffected persons do not transmit disorder.
Some conditions may become evident later in life; allele for disorder may have been passed on to next generation before diagnosis of disease in parent- termed delayed lethal genotype.
What are some examples of Autosomal Dominant Disorders?
Adult polycystic kidney disease
A CT disorder manifested by changes in the skeleton, eyes, and cardiovascular system.
Condition involving neurogenic tumors that arise from Schwann cells and other elements of the peripheral nervous system.
Recessive; allele carried on the X chromosome but not the Y chromosome.
Manifested in heterozygous males lacking the matching unaffected gene on the Y chromosome.
Heterozygous females are carriers.
Homozygous recessive females may be affected.
Inheritance may skip generations.
Example of X-Linked Dominant Disorder:
Fragile X Syndrome- most common genetic cause of cognitive deficits; effects are variable and related to the extent of mutation of the allele.
Examples of X-Linked Recessive Disorders:
Duchenne Muscular Dystrophy
Examples of Chromosomal Disorders:
Down Syndrome- Trisomy 21, may be caused by nondisjunction or translocation
Turner Syndrome XO- Affects females, short stature and infertility
Klinefelter Syndrome XXY- Extra X chromosome is present, infertility, smooth skin, no facial hair, shrinkage of testes
What is used to confirm the disorder of Down Syndrome before birth?
Amniocentesis or chorionic villi sampling
What are the characteristics of Down Syndrome?
Small head, round face, flat facial profile
Slanted eyes and epicanthic fold
Large tongue, high arched palate
Small hangs, single palmar crease
Muscles tend to be hypotonic; loose joints
Delayed developmental stages
Cognitive impairment ranges from mild to major
Delayed or incomplete sexual development- males infertile and females have lower rate of conception
Developmental Disorders are caused by:
Exposure to drugs, chemicals, or radiation during childbearing years.
Acronym for maternal infections that can result in anomalies; routine prenatal screening tests.
Other (Hepatitis B, Mumps, Rubeola, Varicella, Gonorrhea, Syphilis)
When is the most critical time for the embryo?
The first 2 months when the cells are rapidly dividing and differentiating and organogenesis is taking place.
Grade IV Tumors:
Undifferentiated with cells varying in size and shape (anaplasia); this type of tumor is considered highly malignant.
What are the different diagnostic tests for cancer?
X-ray, ultrasound, magnetic resonance imaging, computed tomography
What are the 3 basic mechanisms in which tumors spread?
1. Invasion- refers to local spread, in which the tumor cells grow into adjacent tissues and destroy normal cells; tumors may secrete lytic enzymes.
2. Metastasis- to spread to distant sites by blood or lymph channels; frequently first metastasis occurs in lymph nodes, sometimes they are removed to eradicate any micrometastases that may have been missed.
3. Seeding- the spread of cancer cells in the body fluids or along membranes, usually in body cavities.
What are two common sites for secondary tumors?
Lungs and liver- because cancers spread by normal venous and lymphatic flow.
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