Lec 6: Cancer Flashcards
Cancer - Background
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-> Abnormal cells with uncontrolled growth
- They don’t grow fast, they just don’t stop
- Develops in dividing cells - growing tissues
-> Commonly thought of as one disease
- Individual treatment needed
-> Also called malignancy or neoplasm
- Malignant cancers invade surrounding tissues or spread (metastasize) to distant areas of the body
- Neoplasm = new growth
Incidence/Prevalence
-> Incidence of some CA increasing, some decreasing
-> In CAN, every case reported to prov Cancer Registry -> national level
Etiology and Pathophysiology of Cancer
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go two ways:
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-> Carcinogen
- Normal cells
1 Initiation
- Initiators begin the process of changing the DNA in some of the cells
2 Promotion
- Promotors enhance the development of abnormal cells
-> Tumor formation
1 Benign: noncancerous tumour
2 Malignant: cancerous tumour releases cells into the bloodstream (metastasis)
-> Cancer cells reproduce at an uncontrolled rate
-> Rate at which tumour grows depends on characteristics of tumour, host
Causes of death from cancer - main one is:
Visual slide 10 ***
Other causes:
However, the face of cancer is changing…
: Cachexia
: organ failure, obstruction of organ, airway, blood vessel; increase ICP; circulatory effects; infection
… as many of 2/3 of those diagnosed with cancers are overweight or obese to begin with
Medical Management of Cancer
-> Diagnosis
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- Series of tests looking for tumour biomarkers and evidence of metastasis
- Tumours name according to tissue of origin
(Carcinoma: epithelial tissues,
sarcomas: connective tissues,
lymphomas: lymphatic tissues etc) - oma = tumour
Staging and Clinical Severity
-> After diagnosis, tumour classified and assigned a stage
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Table 10.1 - review for understanding
- Stage of cancer based on cell type, tissue of origin, infiltration and/or size
-> Several systems used - T/N/M
- American Joint Committee System
- Duke’s Staging System (specific for colorectal cancer)
Medical Management of Cancer Interventions
-> Typically involves combinations of treatments
1 2 3
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1 Surgery 2 Chemotherapy 3 Radiation
-> Oldest and most preferred form of treatment for CA
- Removes the bulk of the tumour
- Radiation or chemo may be used before or after surgery
-> Proportion of patients who have surgical proceudre depend on type of cancer, age
-> Side effects depend on location and extent of surgery
2 Chemotherapy
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-> Complex combinations of drugs used in specific sequence to maximize cancer cell death
Goals: - Destroy the cancer cells, shrink the tumour, relieve symptoms
-> Cancer cells develop resistance rapidly - needs multiple drugs
- Often given in a cycle - why?
-> Result in high percentage of cures
-> All existing agents are toxic to other rapidly dividing cells
- Toxic to bone, causes Leucopenia (not enough WBC) thrombocytopenia (not enough platelets) anemia
2 CON’D
(4) Main Types of Chemotherapy
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[KNOW these 4 main types]
-> Inhibit DNA synthesis
- Methotrexate - an analogue of folic acid
-> Inhibit DNA replication and transcription or cell division
-> Hormones
-> Immunotherapy
3 Radiation
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1 2 3
-> Electromagnetic rays, charged particles create free radicals which damage DNA causing cell death
-> Goals: same as those for chemotherapy
- Destroy cancer cells, shrink tumour, relieve symptoms
-> Three kinds of radiation therapy
1 External Beam Therapy
2 Brachytherapy: sealed radioactive sources placed in the body - EX radioactive ‘seeds’ used for prostate
3 Systemic Radiation Therapy: oral or IV, travel through the body to damage DNA of cancer cells, for metastasized cancers*
3 CON’D
-> Side effects common to all forms: ____ and ____
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-> fatigue and anorexia
- external beam radiation - effects usually limited to area being treated
Nutrition Management of Cancer
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-> Goal:
-> Nutritional status can be negatively affects by malignancy in two ways:
- Implications of cancer (systemic, local)
- Implications of medical management
-> Goal: is to PREVENT malnutrition
Nutrition implications of Cancer - Anorexia
Due to…
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Cancer Cachexia
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FYI visual - but check it out - slide 31
- Feeling poorly, taste changes, feeling full because of reduced GI secretion, GI issues, psychological problems, systemic appetite-depressing factors
-> Anorexia often primary cause of weight loss - Anti-emetics help (what are these?- decrease feelings of vomiting)
-> Predominant nutritional problem
-> Variant of PEM
- Mobilization of fat and muscle
-> Characterized by
- severe weight loss, anorexia, nausea, early satiety, muscle wasting, increased REE, immunosuppression, fluid retention
-> Biochemical basis - cytokine involvement
-> Metabolic basis
- insulin resistance, lipolysis, loss of fat and muscle, acute phase protein production
-> Death occurs with 25% to 30% weight loss
- Cachexia decreases quality of life
-> Cachexia happens in obese patients, but it can look different - they may retain much of their fat tissue, but have severe muscle loss
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Metabolic changes associated with cancer - Energy Expenditure
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[So what do you do? - choose an eqn, monitor and adjust as needed]
- Frequently observed
- Inconsistent and variable
- Common to find increased sensitivity to bitter flavours, like red meats
- Aversions develop - why?
(may develop during/after antineoplastic therapy)
-> Hyper-, Hypo-, normometabolism possible
- Hypometabolism happens if there is muscle wasting-why?
-> Different than what is observed in chronic starvation in which REE drops - why?
-> Predicting energy needs is challenging
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so what’s going on…
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PRO metabolism in Cancer is more like:
a) Metabolic stress
b) Starvation
c) Normal Protein metabolism
- increased lipolysis
- decreased lipogenesis
- result is body fat loss, hyperglyceridemia
- Changes at all levels (contributes to cachexia)
- Insulin resistance, glucose intolerance, increased gluconeogenesis, increased Cori cycle activity
- Patients typically hyperglycemic
- Tumours LOVE glucose
- Intense depletion of FFM
… - AA not spared
- Proteolysis, decreased protein synthesis
- Result is muscle atrophy
- increased hepatic synthesis of acute-phase proteins
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Eutopic Hormones in Cancer
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-> Hormones usually made in small amounts in the body already, and whose production increases when cells become cancerous
- Eg. breast cells produce insulin
- Bronchial epithelial cells produce calcitonin
-> Every known naturally-occuring hormone can be produced by >/= 1 human tumour types
-> Energy metabolism hormones can be affected
