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