L8 Neoplasia III Flashcards
Tumors begin as monoclonal; what happens next?
Sub-clones arise from the descendants of the original transformed cell by multiple mutations; these cells have specific evasive functions.
___ agents inflict genetic damage.
Carcinogenic
What are three types of carcinogenic agents?
- Chemicals
- Radiant energy
- Microbial agents
What is the difference between direct acting and indirect acting chemical carcinogens?
Direct acting require no metabolic conversion; indirect acting require metabolic conversion
Carcinogenicity may be augmented by promoters - what are these?
Non-tumorigenic compounds which facilitate the induction of cell proliferation in the initiation-promotion sequence
Given the toxin, name the organ affected and the resultant cancer: vinyl chloride
Liver; angiosarcoma
Given the toxin, name the organ affected and the resultant cancer: nitrosamine (smoked foods)
Stomach; gastric cancer
Given the toxin, name the organ affected and the resultant cancer: asbestos
Lung; mesothelioma, bronchogenic carcinoma
Given the toxin, name the organ affected and the resultant cancer: arsenic
Skin; squamous cell carcinoma
Given the toxin, name the organ affected and the resultant cancer: napthalene (analine) dyes
Bladder; urothelial carcinoma
Given the toxin, name the organ affected and the resultant cancer: aflatoxin B
Liver; hepatocellular carcinoma
What are some sources of radiation carcinogenesis?
- Sunlight (UV)
- X-rays
- Nuclear fusion/ionizing radiation
- Fission by-products
- Radionucleotides
How does ionizing radiation act as a carcinogen?
Chromosome breakage, translocations, point mutations, all leading to genetic damage
What type of cancer is associated with ionizing radiation?
Papillary carcinoma of the thyroid
How does UV light act as a carcinogen?
Damages DNA by forming pyrimidine dimers
What type of cancer is associated with UV light?
Skin, squamous cell, basal cell, and melanoma
True or false - radiation initiation is reversible due to its long latent period.
False - it is irreversible despite a long latent period
What is the defect in xeroderma pigmentosum?
Defect in nucleotide excision repair pathway; increased disposition to skin cancer
What is a type of RNA virus that can cause cancer, and what type?
Human T-cell lymphotropic virus (HTLV-1) –> T cell leukemia/lymphoma
What are 3 types of DNA viruses that can cause cancer, and what type?
- HPV –> benign warts, cervical cancer
- Epstein Barr Virus (EBV) –> Burkitt lymphoma, nasopharyngeal carcinoma
- Hepatitis B/C –> hepatocellualr carcinoma
What is a type of bacteria that can cause cancer, and what type?
Helicobacter pylori –> gastric adenocarcinoma, MALT lymphoma
What are the 4 major anti-tumor effector mechanisms?
- Cytotoxic T lymphocytes
- NK cells
- Macrophages
- Humoral mechanisms
___ patients are at an increased risk for cancer development.
Immunosuppressed
What are several ways cancers can evade the immune system?
- Eliminate strongly immunogenic sub-clones.
- Fail to express HLA class I, escape cytotoxic attack
- Suppress host immune response by secreting TGF-beta, expressing FasL, and activating tRegs.
