Biology 207 Spring 2004
Biology of Cancer
Lecture 3 "Cancer types and stages"
Reading: Chapter 2, Cooper
Lecture Outline:
1. Classification of cancers
2. Clinical staging
Lecture notes:
1. Cancer classification
· There are >100 different types of cancers.
· Arise from abnormalities in cell growth and division.
· Originate from different types of normal cells.
· Vary in rates of growth and ability to spread.
Classification of cancers based on cell/tissue origin
Carcinomas: cancers of epithelial cells.
· Epithelia: cell that cover surfaces, for example skin, lining of digestive tract. Glands also are epithelia.
· Make up 90% of human cancers.
Sarcomas: tumors of connective tissues.
· Connective tissues lie below epithelia and hold things together or support the body. Some examples are muscle and bone.
· Cancers are rare, because these cells do not reproduce very often.
Leukemias and Lymphomas: Cancers of blood cells.
· Leukemias are cancers of circulating blood cells or stem cells of the bone marrow.
· Lymphomas are usually solid tumors in lymphatic organs (system that cleanses the blood).
· Comprise 8% of all human cancers.
Further classification of cancers
(1) site of origin: lung, breast carcinomas
(2) cell type: squamous cell carcinoma: cancer of flat epithelial cell
· Skin cancer: 3 types
o Basal cell carcinoma
o Squamous cell carcinoma
§ Account for 90% of skin cancers; cure rates 99%; rarely metastasize.
o Melanoma--Cancer of pigment forming cells. Can metastasize rapidly. Fatal to 20% of patients.
Cancers of glands: prefix adeno-
Example adenocarcinoma
Cancers of embryonic tissues: suffix -blastoma
Neuroblastoma: Childhood cancer of neurons.
Retinoblastoma: Childhood eye cancer.
Historical names: Named after discoverer
· Wilm's Tumor (a childhood kidney cancer)
· Hodgkin's disease (a type of lymphoma)
· Kaposi's sarcoma (cancer of blood vessels, rare except associated with immunodeficiency and HIV infection)
2. Clinical staging of cancer
a. Staging specific to particular types of cancer,
· prostate cancer—Gleason system
· lung cancer—Stages I-IV, now correlated with TNM staging
b. Universal system: "TNM system"
· Developed by US and International committees
· Based on 3 considerations
o T = condition of primary tumor (values usually T1-T4)
o N = extent of lymph node involvement (values N0-N2)
o M = extent of distant metastasis (values M0 or M1)
· Correlation between tumor staging and prognosis/treatment
o T low stage, no lymph node involvement, good cure rate
o T high stage, lymph nodes involved, metastasis, poor survival rate
Example: TNM staging of colon cancer, Table 2.2 Cooper
Five year survival rate for colon cancer
Stage / Survival rate (5 yr)T1N0M0
T2N0M0 / ~90%
T3N0M0 / ~80%
T4N0M0 / ~60-70%
T3N1M0 / ~50%
T4N1M0 / ~40%
· For early stage: surgery usually leads to cure
· For T3, T4, N1 or N2: radiation and/or chemotherapy useful in addition to surgery
· M1 stage: No longer curable; treatments can prolong life
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