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Neoplasia
Pathophysiology of tumors and cancer
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The following pictures and descriptions were found at:
www-medlib.med.utah.edu/WebPath/NEOHTML
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Cells normally differentiate, grow, mature and divide.
These are regulated processes, balanced in a healthy system such that cell birth is nearly equal to cell death
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Regulation of cell division includes:
1. Signaling by biochemicals released from one cell that interact with other cells
growth factors or cytokines
2. Other external factors , such as contact inhibition
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3. Genes and internal factors that promote and regulate cell division
genes and chromosomal factors - telomeres
braking proteins – Rb proteins
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A tumor cell’s growth is autonomous – independent of controls
Neoplasm – a type of tumor – group of neoplasic cells
Study of tumors is oncology from Greek for tumor
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Two major types: Benign and Malignant (table 6.2)
Benign: grow slowly
low mitotic rate
well differentiated
not invasive; well-defined borders
remain localized; do not metastasize
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Malignant – cancer – from Latin for crab
autonomy and anaplasia
Grow rapidly ; high mitotic index, poorly differentiated; do not have a capsule; invade surrounding structures; can metastasize from the primary to a secondary site (metastasis).
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Malignant tumors – use embryonic origin of tissue
Carcinomas come from ectoderm and
Endoderm - epithelial and glandular tissue
Sarcomas arise from mesoderm
connective tissue, muscle, nerve and endothelial tissues
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Genetic Basis of cancer
• Older theory : Initiation-promotion-progression
• “Multi-hit” hypothesis
• Cancer is a disease of aging
• Clonal proliferation
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Viral causes of cancer:
viruses assoc. with about 15 % of cancers world wide – us. Cervix or liver
hepatitis B or C in chronic form
Human papilloma virus
spread through sexual contact
HPV integrates into DNA and uses viral oncogenes
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Epstein-Barr and Kaposi sarcoma
both herpes viruses
Human T cell leukemia-lymphoma virus
blood transfusions, needles, sex and breast feeding
infections may be asymptomatic
may have high incidence, but low #’s of cancer
cofactors increase the risk of cancer
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Bacterial causes of Cancer
Helicobacter pylori infects >1/2 world’s population
assoc. with B cell lymphomas of the stomach
treatment with antibiotics can cause regression of lymphoma
Tumors arise in MALT -MALTomas
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Environmental factors
• Tobacco use
• Diet
• Alcohol use
• Sexual and reproductive behavior
• Air pollution
• Occupation hazards – asbestos
• UV radiation and other radiation
• hormones
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Gene-Environment Interactions:
Exposure to environmental agents can cause increased risk of cancer
cancer in lab animals – carcinogens
Comparisons of populations
genetics vs. lifestyle
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Diagnosis:
screening procedures and blood tests:
Tumor markers
substances on plasma membranes
in blood, spinal fluid or urine
hormones, genes antigens or antibodies
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Tumor spread
• Local spread– Cellular multiplication
• Function of generation time• Growth if cell reproduction > cell death
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Stages of cancer spread:
Stage 1 – confined to site of origin
Stage 2- cancer is locally invasive
Stage 3 – cancer has spread to regional structures
Stage 4- cancer has spread to distant sites
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Patterns of spread: Metastasis
• Direct or continuous extension
• By lymphatics or blood stream– As clumps or as single cells– Lymphatics most common
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Clinical manifestations of Cancer
• Pain– Usually not in early stages– 60 – 80 % of terminally ill– Psychogenic, cultural and physiologic
components– Due to pressure, obstruction, stretching,
tissue damage or inflammation
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Clinical manifestations of Cancer
Fatiguesleep disturbancesbiochemical changesloss of muscle function
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Clinical manifestations of Cancer
Cachexia – wastinganorexiaearly satietyweight lossanemiamarked weakness taste alterationsaltered metabolism
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Clinical manifestations of Cancer
Anemia
chronic bleeding
malnutrition
medical therapies
malignancy in blood forming organs
Administer erythropoietin
Clinical manifestations of Cancer
• Infection
• most significant cause of complications and death
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Cancer Treatment• Chemotherapy
– Cytotoxic drugs + body defenses
• Combination chemotherapy
• Radiation
• Surgery
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Side effects of treatment• Gastrointestinal tract:
– Oral ulcers– Malabsorption– Diarrhea– Vomiting – caused by effects on CNS
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Side effects of treatmentBone marrow:
chemo and radiation suppress bone marrow
decrease in red blood cells, white blood cells and platelets
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Side effects of treatmentHair and skin:
alopeciaskin breakdown and dryness
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Side effects of treatmentReproductive tract:
affects gametespremature menopausealso due to damage of hypothalamus
and/or pituitarysperm or embryo bank