What are neoplasms?
means "new growth"
uncontrolled growth of cells whose proliferation cannot be adequately controlled by normal regulatory mechanisms
note: not all neoplasms are tumors
How are human tumors classified?
What are the main differences between benign and malignant tumors?
benign = limited growth potential
- sharply demarcated
- often encapsulated
- uniform cells
How do tumors metastasize?
They can go
- through lymphatics
denotes a process in which cells move from one site to another in the body. benign tumors NEVER metastasize.
List a few benign mesenchymal tumors and their malignant equivalents.
Mesenchymal = CT, muscles, bones
How do carcinomas differ from sarcomas?
carcinoma = malignant tumor of epithelial cells
sarcoma = malignant tumors of mesenchymal cells
Define lymphoma, glioma, seminoma, and teratoma.
teratoma = benign tumor, embryonic cell
seminoma = malignant, testicular seminiferous epithelium
glioma = malignant, brain glial cells
lymphoma = malignant, lymphoid cells
List three eponymic tumors.
- hodgkin's lymphoma
- ewing's sarcoma (bones)
- kaposi's sarcoma (skin)
What is the difference between tumor staging and grading?
staging = clinically assessing the extent of tumor spread
grading = based on histological examination
Compare normal and malignant cells, taking into account their morphology, some basic biologic funcitons, and biochemical properties.
MAlignant cells have
- simplified metabolism >> loss of highly specialized functions
- there are no definitive biochemical tests to tell
- may secrete fetal features (eg AFP)
How do tumor cells gow in vitro?
They can survive much longer than normal cells. "Immortal"
There is no contact inhibition, and the cells pile up to form aggregates and nodules. Have autocrine stimulation
What are the most important exogenous and endogenous causes of cancer?
- physical agents
How do scientists identify potential human carcinogens?
begins with clinical observations . . . which are amplified by data obtained from epidemiological study . . . additional studies, experimental animal studies, in vitro studies . . .final goal is identification and isolation of cancer genes.
List some chemical carcinogens and explain how they cause cancer.
Chemical enter the body and can act several ways
- at the site fo digestion in the intestines
- at the site of metabolic activation in the liver
- at the site of excretion in the urine
Compare the carcinogenic action of oncogenic RNA and DNA viruses.
DNA viruses induce malignant transformation by integration into the genome.
Acute-transforming RNA viruses produce malignant transfromation by transduction.
Slow-transforming RNA viruses produce malignant transformation by transfection/insertion of promoter gene.
Which human DNA viruses have been linked to cancer?
- human pipilloma virus
- Hepatitis B
- Human T cell lymphoma/leukemia virus 1
How do proto-oncogenes transform into oncogenes?
4 basic mechanisms
1. point mutation
2. gene amplification
3. chromosomal rearrangement
4. insertion of the viral genome
What are tumor suppressor genes, and how do they cause cancer?
Tumor suppressor gene = regulatory genetic mechanisms that protect against activated/acquired oncogenes
mutations of the genes can lead to cancer and inability to suppress
How does ultraviolet light cause cancer?
UV light damages the DNA of skin, thus causing mutations that lead to malignant transformation.
Explain the role of heredity in the pathogenesis of cancer.
Tumor genes can be transferred through mendelian traits
Describe the immune response to tumors and explain the clinical significance.
Tumor antigens can induce an immune response: NK, B lymphocytes, T-cytotoxic cells, macrophages, neutrophils
What are the common warning signs of neoplasia?
Change in bowel or bladder habits
A sore that does not heal
Unusual bleeding or discharge
Thickening or lump in the breast, testicles, or elsewhere
Indigestion or difficulty swallowing
Obvious change in the size, color, shape, or thickness of a wart, mole, or mouth sore
Nagging cough or hoarseness
Explain the pathogenesis of common local symptoms of neoplasia.
As they grow, they compress adjacent tissues. Invasion of blood vessels and erosion of normal tissues. May cause narrowing or obstruction in lumens.
What is the pathogenesis of tumor-induced cachexia and hypercoagulability of blood?
cachexia occurs b/c the cancer competes for nutrients and drains energy from the body.
hypercoagulability occurs b/c of tumor degredatoin or secretions
Define paraneoplastic syndrome and provide specific examples of syndromes dominated by endocrine, hematologic, or neuromuscular changes.
paraneoplastic syndrome occurs when various substances are secreted by cancer cells . . . such as ACTH and parathyroid hormone
List some risk factors for common cancers.
smoking, family history, promiscuity, hormal imbalance and treatment, sun exposure, fair skin, old age
What is the difference between incidence and prevalence of cancer.
incidence = number of new cases in a specific period and defined population
prevalence = number of all cases
The incidence of which cancers has increased or decreased over the past 60 years?
Discuss important safeguards against cancer.
breast: annual mammogram and breast exam @40
lung: stop smoking
colon: regular colorectal testing @50
cervix: beginning 3 yrs after becoming sexually active; regular PAP 1-2 yrs; @30, every 2-3 yrs if normal
prostate: @50, decide about testing
skin: avoid sun/tanning
oral: routine examination
Cells exhibit new features not inherent to the tissue of their origin.
variation in size and shape of tumor cell nuclei
Malignant vs. Benign
malignant = uncontrollable growth, kill host
- infiltrate normal tissues
- lack of borders
- heterogenous cells
- reduced organelles
- high nuclear to cytoplasmic ratio
- aneuploid (abn chromosomes)
- not specialized functions
Benign tumors of epithelial cells
benign protuberant tumors of the skin