3. 2.2 Tumor arise from many cell types
throughout the body
The most common types of human neoplasms
derive from epithelium – that is, the cells
covering internal or external surfaces of the
body. The neoplasms which are derived from
epithelium are called “carcinomas”. These
tumors are responsible for more than 80% of
the cancer-related deaths.
4. Most of the carcinomas fall into
two major categories
Carcinomas arising from stratified squamous
epithelium are designated squamous cell carcinomas,
whereas those arising from glandular epithelium are
termed adenocarcinomas.
7. The 1st group of nonepithelial cancers derived from
various connective tissues are called “sarcomas” ,
constituting ~1% of the tumors in the oncology clinic.
Sarcomas derive from a variety of mesenchymal
cell types: fibroblasts (connective tissues)
adipocytes (fat)
osteoblasts (bone)
myocytes (muscle)
mesenchyme: undifferentiated mesoderm-derived cells set
in a gelatinous ground substance, from which
connective tissue, bone, cartilage, and the
circulatory and lymphatic systems develop.
9. The 2nd group of nonepithelial cancers arise from various
cell types of blood-forming tissues.
lymphoma – solid tumors of lymphocytes, most
frequently found in lymph nodes
leukemia – tumors of “white cells” of the blood,
usually moving freely through the circulation
12. “oma” usually indicates a tumor. For
example, carcinoma, sarcoma, lymphoma,
myeloma, neuroblastoma, etc. Rarely, the
“oma” describes a nonneoplastic conditions
such as granuloma, which is a mass of
granulation tissue resulting from chronic
inflammation or abscess.
13. Classification of Human Tumors by Tissue Type
_____________________________________________________
Tissue of Origin Benign Malignant
_____________________________________________________
Epithelium
surface epithelium papilloma carcinoma
glandular epithelium adenoma adenocarcinoma
Connective tissue
fibrous tissue fibroma fibrosarcoma
bone osteoma osteosarcoma
Endothelial tissue
blood vessels hemangioma hemangiosarcoma
lymph vessels lymphangioma lymphangiosarcoma
14. Classification of Human Tumors by Tissue Type
______________________________________________________
Tissue of Origin Benign Malignant
______________________________________________________
Neural tissue & its
derivatives
glial tissue glioma glioblastoma multiforme
meninges meningioma meningeal sarcoma
nerve sheath neurofibroma neurofibrosarcoma
melanocytes pigmented nevus malignant melanoma
(mole)
retina 視網膜 - retinoblastoma
etc.
_______________________________________________________
15. 2.4 Cancers seem to develop progressively
The development of tumor is a complex,
multi-step process.
(Chapter 11 - Multistep tumorigenesis)
16. Kleinsmith, L. J. Principles of Cancer Biology. Pearson Education, Inc. 2006 Fig. 1-3
Four major types of new tissue growth
肥大
增生
不正常發育
惡性增生
(腫瘤形成)
17. Kleinsmith, L. J. Principles of Cancer Biology. Pearson Education, Inc. 2006 Fig. 1-4
Comparison of normal and neoplastic
growth in the epithelium of the skin
In normal skin, each
cell division gives rise
to one cell that retains
the capacity to divide
and one that
differentiates.
21. - The term neoplasm, meaning “new growth”, is often
used interchangeably with the term tumor to signify
an abnormal growth.
- Tumors are of two basic types: benign & malignant.
- Malignant neoplasms or cancers have distinguishing
features that enable the pathologists or experimental
biologists to characterize them.
22. A Malignant Tumor vs a Benign Tumor
- depending on the degree of aggressive growth
1. Malignant tumors invade and destroy adjacent normal
tissues; benign tumors grow by expansion, are usually
encapsulated, and do not invade surrounding tissue.
Benign tumors may, however, push aside normal tissue
and become life-threatening if they press on nerves or
blood vessels.
23. A Malignant Tumor vs a Benign Tumor
2. Malignant tumors metastasize (轉移) through lymphatic
channels or blood vessels to lymph nodes and other
tissues in the body. Benign tumors remain localized
and do not metastasize.
primary tumor – tumor growing at the anatomical site where tumor
progression began and proceeded to yield this mass
metastatic tumor – tumor forming at one site in the body, the cells
(metastases) of which derive from a tumor located elsewhere
in the body
25. A Malignant Tumor vs a Benign Tumor
3. Malignant tumor cells tend to be “anaplastic” or less
differentiated than normal cells of the tissue in which
they arise. Benign tumors usually resemble normal
tissue more closely than malignant tumors do.
anaplasia: reversion to a less differentiated structure
26. A Malignant Tumor vs a Benign Tumor
4. Malignant tumors usually, but not always, grow
more rapidly than benign tumors. Once they reach
a clinically detectable stage, malignant tumors
generally show evidence of significant growth, with
involvement of surrounding tissue, over weeks or
months, whereas benign tumors often grow slowly
over several years.
27. A Malignant Tumor vs a Benign Tumor
5. Malignant neoplasms continue to grow even in the
face of starvation of the host; they press on and
invade surrounding tissues, often interrupting vital
functions. The most common effects on the patient
are cachexia (extreme body wasting, 虛弱),
hemorrhage (出血) , and infection (感染).
28. Comparison of benign and malignant growths
_____________________________________________
Feature Benign Malignant
_____________________________________________
Metastasis no yes
Invasion no yes
Edges encapsulated irregular
Growth rate low high
Nuclei & nucleoli normal variable,
irregular
Life-threatening uncommon usual
_____________________________________________
usually
30. X Chromosome Inactivation
- In the somatic cells, one of the two X
chromosomes is randomly (in higher
mammals) inactivated in the cells of
early female embryo and remains
inactivated in all descendants.
