Introduction to Cancer Biology Flashcards
What is cancer?
A group of different malignant diseases that will occur:
at different ages.
with different rates of growth, differentiation, abilities to be detected, invasiveness, capacities to spread or metastasize.
with different treatment responses and prognoses
What fundamental trait do all types of cancer share?
They are diseases of the genes in that they are the consequence of flaws in the genome of the cancer cell.
What genetic alterations that cause cancer are considered caused by “nature”?
Eg. inherited cancer syndromes, immune deficiencies
What genetic alterations that cause cancer re considered to be caused by “nurture”?
Poor deit, smoking, etc.
What three types of cell damage cause cancer?
Malignant growth is a result of DNA changes, gene transcription or translation.
What do the cellular changes that cause cancer lead to?
Leads to transformation of normal cell components into uncontrolled proliferation, spread, and/or metastasis
How are tumours identified?
Tumours are identified according to the tissue of origin and whether they are benign or malignant.
What is the suffix for benign and malignant tumours?
“oma” (Greek for tumour)
What prefixes are given to designate epitehlial origin or mesenchymal origin?
Carcin - epithelial origin
Sarc - mesenchymal
What three things does the rate of tissue growth in normal and cancerous tissue depend on?
Duration of the cell cycle
Number of actively dividing cells
Cell loss
What is a proto-oncogene?
The genetic portion of DNA that regulates normal cell growth and repair e.g. ras
What is a tumour suppressor gene?
The genetic portion of DNA that stops, inhibits or suppresses cell division (this process is disrupted when the gene mutates)
What is an oncogene?
Altered for of normal proto-oncogene that may give rise to cancers by interfering with normal cell growth, apoptosis, differentiation.
What is the difference between tumour supporessor genes and proto-oncogenes?
Tumour supporessor genes cause cancer when they are inactivated; when a proto-oncogene mutaates into an oncogene then it is activated.
What is carcinogenisis?
The process in which normal cells are transformed into cancer cells.
What starts the process of carcinogensis?
Starts with a single cell that has genetic changes.
What is the stochastic model (Knudson’s random “two hit” model)?
Any cell may be the target of carcinogenesis.
Suggests each cancer cell has the ability to multiply and form new tumours.
What is the Cancer Stem Cell model?
Model the most supported by cancer reserachers.
The model states that many different types of cancer cells exist (demonstrating heterogeneity), and with proliferation comes cell division where all the cells have the ability to multiply but only one has the ability to become a new tumour - the cancer stem cell.
Once the tumour is established, the heterogenous cells proliferate and the cancer stem cell enters the G0 (resting) phase of the cell cyl.es
What are the three stages of multi-stage theories of carcinogenesis? (3)
Initiation
Promotion
Progression
What is the initiaton phase of carinogenesis?
Exposure of a cell to a carcinogen or initiating agent, that makes the cell susceptible to malignant transformation.
What are initiating agents?
Initiating agents may be chemical, biological, or physical agents that are capable of causing irreversible changes in cell DNA.
- viral
- environmental
- lifestyle
- genetic factors
What is the promotion phase of carcinogenesis?
Promoting agents cause unregulated and accelerated growth in cells that have been previously initiated.
This process can be reversible if the promoting agents are removed early enough (cancer-reversing/cancer-suppressing agents, host characteristics, time/dose limits of exposure).
What is a complete carcinogen?
A chemical carcinogen that can initiate and promote malignant transformation.
What is the progression phase of carcinogenesis?
At this stage, the cells acquire the malignant characteristics eg. changes in growth rate, invasive ability/potential, angiogenesis.
When a tumour is evident clinically, the differences in individual cells can be detected eg. each cell may grow at a different rate (heterogeneity).
What is differentiation?
Differentiation refers to how different the tumour cells are from the cells from which they originated.
According to Hanahan, what are the 6 essential alterations in cell physiology that dictate malignant growth?
Evading apoptosis Self-sufficiency in growth signals Insensitivity to anti-growth signals Sustained angiogenesis Limitless replication potential Tissue invasion and metastasis
How many cancers arise from inhereted genetic mutations?
10%
What are the characteristics of genetically predisposed/inherited cancers?
Younger than expected onset of cancer Multiple generations Multiple family members Same or related cancer Presence of rare cancers and other characteristics
What are the clinical implications of genetically predisposed/inherited cancers?
The presence of certain mutated genes can have diagnostic and prognostic value.
Preventing gene mutations is a focus of some chemoprevention clinical trials.
Having an understanding of genetic changes may result in new targeted treatments.
In nursing practice, an understanding of carcinogenesis enhanges care, allows nurses to assist in the translation of information for patients and their families about prevention, health promotion, diagnostics, treatments and follow-up
What are two environmental factors that are carcinogenic?
Ionizing radiation
Ultra violet radiation
What are some sources of ionizing radiation?
Natural sources and frome xposure to diagnostic/therapeutic sources eg. radiation therapy, x-rays
Wat are some sources of ultraviolet radation?
Sun/tanning bed exposure and industrial sources like welding arcs.
What are characteristics of chemical carcinogens?
Direct acting do not require activation eg. nitrogen mustard and other antineoplastic drugs (chemotherapy)
Initiators require metabolic activation eg. cigarette smoke
What do viral carcinogens do?
Infect DNA and RAN that may lead to the formation of oncogenes and result in cell mutations.
What two things might affect someone’s vulnerability to viral carcinogens?
Age and immune function
What are some examples of viral carcinogens?
Epstein-Barr herpesvirus (burkitt’s lymphoma, nasopharyngeal cancer)
Human papillomavirus (HPV) - cervical, anal, oropharyngeal cancers
Human herpesvirus 8 (HH8) - Kaposi’s sarcoma
Hepatitis B and C viruses - hepatocellular cancers
HIV - cofactor often due to immunosuppresive properties
