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Introduction to Cancer
DefinitionsThe word “cancer” comes from
the latin word for crab.
The Greek word oncos means swelling and where we get the word oncology or oncologist.
What is the Latin word for swelling?
Tumor
Neoplasia (Gk. new growth)
“A neoplasm is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after cessation of the stimuli which evoked the change.”
--Dr. R. A. Willis
Benign vs. malignantWell-differentiated - when cancer
cells resemble normal surrounding cells.
benignPoorly-differentiated – when
cancer cells do not resemble normal surrounding cells.
malignant
benign – well-differentiated.
malignant-poorly differentiated
Benign:
grow slowly
low mitotic rate
well differentiated
not invasive; well-defined borders
remain localized; do not
metastasize
Malignant
Grow rapidly
high mitotic index
poorly differentiated
do not have a capsule
invade surrounding structures; can metastasize
Nuclei of cellsHave an abundance of DNA and
are therefore large.Hyperchromatic- stain darkly
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In contrast, this hepatocellular carcinoma is not as well circumscribed (note the infiltration of tumor off to the lower right) nor as uniform in consistency. It is also arising in a cirrhotic (nodular) liver.
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Malignant neoplasms are also characterized by the tendency to invade surrounding tissues. Here, a lung cancer is seen to be spreading along the bronchi into the surrounding lung.
This is an example of metastases to the liver. Note that the tan-white masses are multiple and irregularly sized. A primary neoplasm is more likely to be a solitary mass. Metastasis is the best indication that a neoplasm is malignant.
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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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TNM system:
tumor spread
node involvement
presence of distant metastasis
Staging may influence choice of treatment
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Staging TNM system
1.Size of tumor – T0, T1, T2,T3
2.Degree of local invasion – lymph node involvement
3.Extent of spread – metastasis
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Patterns of spread: MetastasisDirect or continuous extensionBy lymphatics or blood stream
◦As clumps or as single cells◦Lymphatics most common
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Distribution and common sites of distant metastases• often occurs in the first capillary bed
encountered•Others show “organ tropism”•Due to:• Local growth factors or hormones• Preferential adherence to the surface• Presence of chemotactic factors
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Clinical manifestations of CancerPain
◦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
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
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Clinical manifestations of Cancer
Leukopenia and thrombocytopeniatumor invasion of bone marrowchemotherapy or radiation
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Cancer TreatmentChemotherapy
◦Cytotoxic drugs + body defenses Single agent Combination chemotherapyAvoids single agent resistanceCan use lower doseBetter remission and cure rate
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Cancer TreatmentRadiation
targets DNAkill tumor without damage to
surrounding tissuestumor must be accessible
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Cancer Treatment
Surgerymethod of choice can remove entire tumordebulkingadjuvant chemotherapy or
radiationpalliation