20 - Oncology Basics Part 1 Flashcards
What are proto-oncogenes ?
- Normal cellular genes that are important regulators of normal cellular processes
- Mutations that alter their expression can activate them to act as oncogenes (tumor-inducing)
What are tumor suppressor genes?
- Suppress growth of tumors
- Mutations render them inactive allowing tumors to develop
What is the immune system’s response?
to reject or destroy cells perceived as non-self
Describe immunologic surveillance
- Lymphocytes continually check cell surfaces, detect and destroy cells with abnormalities
- Involves cytotoxic T-cell natural killer cells, macrophages, and B lymphocytes
- Some cancer cells have changes on their surface antigens (Tumor-associated antigens)
What are some escape mechanisms by which cancer cells evade immune system ?
- Suppression of factors that stimulate T-cells
- Weak surface antigens allow cancer cells to “sneak through” surveillance
- Development of tolerance of immune system
- Suppression of immune response to products secreted by cancer cells
- Induction of suppressor T-cells
- Blocking antibodies that bind TAAs (tumor associated antigens)
Describe altered cell growth
- “Immortality”: unlimited number of cell divisions
- growth without “go” signals
- growth factors, cell-to-cell adhesion molecules, extracellular matrix components
- ignoring “stop” signals
- loss of contact inhibition: invade neighbouring cells, keep dividing
- loss of cell cycle control
- avoidance of APOPTOSIS
Body cells are not immortal and can only divide a limited number of times due to _____
telomeres
What are telomeres?
repeated DNA sequence and protective caps on each chromosome and are held in place and maintained by enzyme telomerase
Telomeres become smaller and smaller with each cell ___
division
______ is increased in cancer
telomerase
Process of Tissue Invasion & Metastasis
Getting into the bloodstream: altered adhesion and mobility
Surviving in the bloodstream: altered anchorage-dependent growth
Getting back into tissue: extravasation and attraction to adhesion molecules in metastatic site
Angiogenesis is important component
What is angiogenesis ?
Tumor needs a blood supply for it to grow.. Will send out growth factors (ex. VEGF) to get blood supply
What can cause cancer?
1) External stimuli causing genetic mutation:
-Carcinogens:
Chemicals: tobacco smoke, arsenic, EtOH, vinyl chloride, benzene
Diet
2) Exposure to viruses
3) Genetic abnormalities (inherited/heritable)
- Oncogenes, porto-oncogenes, tumor suppressor genes
- Inherited genetic risk: 5-10% of cancers
4) Chromosomal abnormalities (spontaneous)
- Increased #, deletion, translocation, breakage
5) Immune system abnormalities
Most common virus that can cause cancer?
Hep B - liver cancer
What are some inheritable genetic mutations?
- BRCA-1: breast, ovarian, prostate
- BRCA-2: breast
- RB1: retinoblastoma
- WT1: Wilm’s tumor
- Li Fraumeni (p53 supressor mutation): breast, brain, acute leukaemia, soft tissue sarcomas, osteosarcomas, adrenal cortical carcinoma
- Hereditary non-polyposis colorectal cancer
- Familial adenomatous polyposis
- MEN1 & MEN2: multiple Endocrine Neoplasia
Up to 80% of cancers could be prevented if Canadians made healthier choices about ?
- tobacco
- diet
- exercise
- sexual practices (HPV, Hep B/C, etc)
What are some early warning signs for common cancers that should be acted upon ?
- Change in bowel or bladder habits
- Sores that will not heal
- Unusual bleeding or discharge
- Thickening or lump in breast or elsewhere
- Indigestion or difficulty swallowing
- Obvious change in a mole or wart
- Nagging cough or hoarseness
Describe what a histopathology looks like
What it looks like under the microscope
- Tissue of origin
- Tumor grade: how aggressive is it?
- Receptors, chromosomal abnormalities, tumor markers, etc.
Disease stage ?
how far has it spread?
What is a carcinoma ?
- epithelial tissue
- adeno-glandular/columnar
- squamous - squamous
What is a sarcoma ?
- connective tissue
- osteo-bone
- blastoma - embryonal origin
What is a teratoma ?
germ cells
What is a hematologic cancer?
leukemia, lymphoma
metastatic
means it’s spread
Describe the clinical staging of cancer (0-4)
0: cancer in situ
1: tumor limited to tissue of origin
2: limited local spread
3: extensive local and regional spread
4: metastasis (spread)
Describe the TNM Classification of cancer
One example of a classification system - there are MANY staging systems that are disease-specific
T = Tumor size N = Spread to Lymph nodes M = Metastasis
