Week 1 - Cancer Flashcards
Define cellular regulation
- all functions carried out within a cell to maintain homeostasis
- includes responses to extra cellular signals
What are two key concepts of cellular regulation?
- Proliferation
2. Differentiation
Describe proliferation and differentiation in relation to cancer cells
- cancer cells fail to differentiate and excel at proliferation
Cancer is a group of _______
More than 200 diseases
What is cancer characterized by?
- uncontrolled and unregulated growth of cells (proliferation)
Who does cancer occur in?
- in people of all ages & ethnicities
Approximately how many people in Canada have a chance of developing cancer?
- 44% (1 in 2.3)
Describe the chances of developing cancer for each sex: is it similar chances?
- men 45%
- women 43%
= very similar
What are the top 3 cancers to occur in men?
- Prostate
- Lung & bronchus
- Colorectal
What are the 3 most common cancers to occur in women?
- Breast
- Lung and bronchus
- Colorectal
Which age group has the highest percentage of cancer cases?
50-69 (44.9%)
What is the leading cause of death in ever Canadian province?
What is the second?
- since 2008, cancer has been the leading cause (30% of deaths)
- heart disease is in second (21% of deaths)
What are risk factors for developing cancer? (4)
- excessive body weight
- lack of physical activity
- unhealthy eating habits
- excessive exposure to the sun
What are some lifestyle habits that reduce the risk of developing cancer? (3)
- avoid or reduce exposure to known or suspected carcinogens
- eat a balanced diet (includes variety)
- exercise regularly
What are carcinogens?
- any substance that is known to cause or promote the formation of cancer
What are some examples of carcinogens?
- cigarette smoke
- excessive sun exposure
What is a neoplasm
- a tumour
- an abnormal mass of cells which grow and divide without response to normal regulatory controls
What is a benign tumour?
- noncancerous tumour
- does not spread to other tissues or metastasize
What is a malignant tumour?
- cancer
What is the cause of cancer?
- cause is considered unknown
- but current theory of cancer formation involves multiple sequential mutations that impairs a cell’s ability to control it’s cell cycle and replication
What are the 4 characteristics of malignant cells?
- Proliferation without limits ( will endlessly divide)
- Evasion of apoptosis
- Acquisition of vasculature
- Invasion of other tissue and metastasis
Why do malignant cells acquire vasculature?
- as the cells & tumour grows, it needs lots of O2 and nutrients and will become ischemic
- they acquire vasculature to overcome this
List the phases of the normal cell cycle
- G1
- S stage
- G2 stage
- Mitosis
- G0
What occurs during G1
- growth phase
- relatively dormant, some RNA and protein synythesized
What occurs during S phase
- DNA synthesis
What occurs during G2
- more growth
- prep for mitosis
- some RNA synthesized
What occurs during mitosis
- cellular division
- the parent cell splits into 2 daughter cells
What occurs during the G0 phase?
- resting phase
- cells are not in the process of cellular division
What two types of genes are affected by mutations that contribute to the development of cancer?
- Proto-oncogenes
2. Tumour suppressor genes
What do proto-oncogenes do
- regulate normal cellular processes
- ex. Promote growth
What are proto-oncogenes called if they are mutated?
- they become oncogenes
What do tumour suppressor genes do?
- suppress growth
What may happen if tumour suppressor genes are mutated?
- cell may not be able to stop growing
What are two examples of tumour suppressor genes?
- BRCA1 (mutation in this gene can cause breast cancer)
2. P53 (most commonly mutated gene)
Research suggests that human neoplasms result from a. Combo of mutations that activate ______ and inactivate ________
- activate oncogenes
- inactivate tumour suppressor genes
What is an oncogene
- gene that has potential to cause cancer
- was once a proto-oncogene
What is carcinogenesis
- process by which normal cells become transformed into malignant cells
What does carcinogensis typically involve?
- changes in DNA
- most require multiple changes in DNA , which is caused by multiple factors
List 5 things that may cause mutations in the DNA
- Genetic (ex. BRCA1 mutation)
- Chemical
- Environment (ex. UV rays)
- Viral or immunological
- Or from causes not yet identified
What are the 3 steps in cancer development
- Initiation
- Promotion
- Progression
What occurs during initiation stage of cancer?
- the normal cell gets altered by genetic mutation
- genetic mutation can occur thru inherited mutation, after exposure to a carcinogen, an error during DNA replication, etc.
What occurs during the promotion stage of cancer?
- the presence of promoting factors increase cancer development
What can impact promotion of cancer?
- lifestyle factors
- exposure to steroid hormones such as estrogen and testosterone
Describe how estrogen and testosterone can cause promotion during puberty
- during puberty, these hormones are produced to tell cells in reproductive organs to enter the cell cycle & proliferate
- but at the same time, it will also promote the cancer cells to continue dividing
Describe the progression stage of cancer
- this when you have evidence of clinical disease
- the cancer then spreads & metastasizes
What cancer is associated with Epstein Barr virus
- burkitts lymphoma
What cancer is associated with human immunideficiency virus ( HIV)
- kaposi sarcoma
What cancer is associated with hep B virus
- hepatic Elul are carcinoma
What cancer is associated with human papillomavirus
- squamous cell carcinoma (especially cancer of the cervix)
What are the 6 local effects of tumours?
- Compress blood vessels & outgrow their blood supply
- Nutrient trapping
- Replace normal tissue = loss of function
- Liberate toxins & enzymes = destroy normal & tumour tissue
- Obstruct passageways
- Pain
How do tumours cause pain
- by putting pressure on sensory nerves or a visceral structure
- inflammation and bleeding also contribute to pain
Is pain an early sign of cancer?
- it’s rarely an early sign
What does tumours compressing blood vessels and outgrowing their blood supply cause?
- causes ischemia, inflammation, and tissue necrosis
List two examples of how tumours can block a passageway?
- in the lungs can block air flow
- can obstruct the colon
List the 6 systemic effects of cancer
- Weight loss, tissue wasting
- Fatigue
- Bleeding
- Anemia
- Infections
- Paraneoplastic syndromes
What causes weight loss, tissue wasting, and fatigue? (4)
- anorexia
- increased catabolism ( breakdown)
- nutrient trapping
- inflammation
What is cachexia?
- tissue/muscle wasting —> weight loss
How does the inflammatory response contribute to cachexia
- the release of cytokines contributed to increased catabolism & muscle wasting
- cytokines also cause decreased appetite, nausea, etc.
What causes bleeding due to tumours? (3)
- tumour necrosis and erosion of blood vessels
- bone marrow suppression
Bone marrow suppression can occur as a systemic effect due to what 3 things?
- A specific tumour
- Invasion of the marrow
- Secondary to therapy
What bleeds are specifically difficult to treat?
- GI bleeds
What causes anemia due to a tumour? (3)
- can result from blood loss
- iron deficiency (due to nutrient trapping)
- or bone marrow suppression/invasion
Why do infections occur as a systemic effect of cancer?
- bone marrow suppression/invasion =decreased WBC = immunocompromised
What other factors can predispose cancer patients to infections?
- immobility, muscle wasting, fatigue can cause pooling of respiratory secretions and stasis or urine = predispose to opportunist infections
What are paraneoplastic syndromes?
- symptoms that occur that are not attributed to the direct effects of a tumour or metastasis
- any unusual symptoms
What are examples of paraneoplastic syndromes
- abnormal hormones or cytokines secretion by a tumour
- bone marrow suppression
- dementia
- abnormal clotting
- fever
- cachexia
Malignant tumours spread by producing ______
- secondary tumours that are identical to the original primary tumour
What 3 ways do tumours spread?
- Invasion of neighbouring tissues
- Metastasis
- Seeding
Describe invasion of a tumour
- when tumour cells grow into adjacent tissue
How does invasion occur?
- tumour cells lack adhesion molecules & secrete enzymes that allow them to break down the confining connective tissue
What is metastasis
- when tumour cells break free of a tissue and are circulated to distant tissues in the blood or lymph
Where do secondary tumour attach during metastasis
- either contained by local lymph nodes
- attach to capillary beds they come across
What is the most common site of metastasis ? Why?
- the lungs
- pulmonary capillaries are often the first beds encountered by systemic tumour cells
What are all 5 main sites of metastasis? What is the second most common location after the lungs?
- Brain & cerebrospinal fluid
- Lungs
- Liver (second most common)
- Adrenals
- Bone
What is seeding
- involves the spreading of tumour cells along membranes or within fluids other than blood or lymph
What type of cancer commonly spreads thru seeding? Why?
- ovarian
- it is surround by a continuous peritoneal membrane
What are the 3 ways tumour can be classified by?
- Anatomical site / tissue of origin
- Historical analysis (grading of severity)
- Extent of disease (staging)
what are 4 examples of cancer classified based off tissue of origin
- Carcinomas
- Sarcomas
- Lymphomas and leukemias
Where do carcinomas originate from?
- from epithelial tissues
- includes the ectoderm and endoderm
What is included in the embryonal ectoderm
- skin
- glands
- epithelium
What is included in the endoderm
- mucus membrane of respiratory tract, GI, and GU tracts
Where do sarcomas originate from
- the embryonal mesoderm
What is included in the mesoderm
- CT, muscle, bone, and fat
Where do lymphomas and leukemias originate from
- the hematopoietic system
What is the hematopoietic system?
- system responsible for producing the element of blood (RBC, WBC, platelets)
What is the difference between lymphomas and leukemias
- lymphoma = originates in the lymph nodes
- leukemias = occurs in the bone marrow
What is the difference between cancer grading and staging?
- grading = based on how the cancer cells look, determines how fast it will grow
- stage = says the how much cancer is in ur body, where it is, and how far it has spread
How many grades are there for abnormal cells?
4
Describe grade 1 cancer cell
- cells differ slightly from normal cells
- cells are well differentiated
Describe grade 2 of cancer cells
- cells are more abnormal
- moderately differentiated
Describe grade 3 of cancer cells
- cells are very abnormal
- poorly differentiated
Describe grade 4 of cancer cells
- cells are immature & primitive
- undifferentiated
- cell of origin is difficulty to determine
What is staging useful in?
- determining the prognosis (course of development) of a cancer & the most appropriate therapy
- determines the extent of the disease process within the body
How many different stages of cancer are there?
5 ( ranges from 0-4)
Describe stage 0 of cancer
- cancer in situ
- cancer can be removed & cured
- new, early cancer
What does situ mean
- in its original place
- has not spread
Describe stage 1 of cancer
- tumour limited to tissue of origin
- localized tumour growth
- removal = cured
Describe stage 2 of cancer
- limited local spread to lymph nodes but not beyond these local nodes
- removal of tumour and lymph nodes = cured
Describe stage 3 of cancer
- extensive local & regional spread to lymph nodes
Describe stage 4 of cancer
- metastasis
- 2ndary tumour present
- rarely cured and typically lethal
Which stages of cancer are considered or potentially curable? Which aren’t?
- stages 0-2 = curable
- stages 3&4 = not
What classification system is often used to stage a cancer?
TNM classification system
What does the T stand for in TNM classification
- tumour size & invasiveness
- involves measuring the diameter and different sizes correlate to a stage depending of the type of cancer
What does the N stand for in TNM classification
- spread to lymph Nodes
What does M stand for in TNM classification
- metastasis
- if does = stage 4
Are the specifics of the TNM classification system the same for every cancer?
- no it changes for each cancer
What is lymphoma
- malignant tumours of the lymphocytes
Does lymphoma typically involve B or T lymphocytes?
- 90% involve B lymphocytes
What are risk factors for lymphoma (7)
- previous exposure to radiation
- chronic immunosuppressive
- autoimmune disease
- HIV
- hep B/C
- helicobacter pylori infection
- exposure to herbicides & pesticides have also been suspected
What is the most common clinical manifestation of lymphoma
- lymphadenopathy
Describe the development of lymphoma
- typically begins in a single lymph node but will metastasize to adjacent nodes & other areas of the body
What nodes are most commonly affected by lymphoma (3)
- cervical
- supraclavicular
- axillary
What are key characteristics of lymphoma (4)
- asymmetric enlargement of lymph nodes
- weight loss
- fatigue
- immunosuppression
What are the 2 main categories of lymphomas
- Hodgkin disease
2. Non-hodgkin’s disease
Describe cellular origin in hodgkins vs non-hodgkins
- hodgkins = b lymphocytes –> reed sternburg cells
- non-hodgkins = b lymphocytes (90%) and t lymphocytes (10%)
Describe the extent of disease in hodgkins vs no hodgkins
- hodgkins = localized to regional, but may be bulky
- non = disseminated (spread)
What are B symptoms? (3)
- fever
- night sweats
- Weight loss
Describe the presence of B symptoms in hodgkins vs no hodgkins
- hodgkins = common
- non = less common
Describe extranodal involvement in hodgkins vs nonhodgkins
- extranodal involvement = spread to an atomic sites other then the lymph nodes
- hodgkins = rare
- non = common
Describe stage 1 of hodgkins
- involvement of a single lymph node or a single extranodal site
Describe stage 2 of hodgkins
- involvement of 2 or more lymph node regions on the same side
Describe stage 3 of hodgkins
- involvement of lymph nodes on both sides of the diaphragm
Describe stage 4 of hodgkins
- disseminated disease of one or more extralymphatic organs or tissues with or without associated lymph node involvement
What is the Canadian Cancer Society’s 7 Steps to Heakth?
- Be a non-smoking and avoid second hand smoke
- Eat well
- Be active
- Use sun sense
- Follow cancer screening guidelines
- Visit ur doctor or dentist if u notice anything abnormal
- Follow safety instructions at home and work for storing and disposing of hazardous materials
What is meant by “eat well”
- 5-10 servings of fruits and veggies
- high fibre
- low fat
- low alcohol
