5

Question 1

Features of Tumor Spread

Answer 1

• Malignant tumors are often highly invasive.
• Malignant tumors do not respect anatomic boundaries.
• Malignant tumors infiltrate adjacent normal tissues.
• Benign tumors are expansible rather than infiltrative.
• Benign tumors of epithelial origin are usually encapsulated with connective tissue capsule.

Question 2

________ is the single most reliable hallmark of malignancy.

Answer 2

Metastasis

Question 3

Pathways of Tumor Metastasis:
- three method

Answer 3

1. Transcoelomic
2. Lymphatic
3. Hematogenous

Question 4

Pathways of Tumor Metastasis:
1. Transcoelomic

Answer 4

When cancer arise on surface of an abdominal or thoracic structures they encounter few anatomic barriers to spread.
But tumor within these cavities readily spread to cover all visceral and parietal surfaces.

Question 5

1. Transcoelomic - examples

Answer 5

1. mesothelioma (Mesothelium) may be confined to abdominal or pleural cavities.
2. ovarian adenocarcinoma.

Question 6

Pathways of Tumor Metastasis:
2. Lymphatic

Answer 6

Carcinoma metastasize via the lymphatic system.

Question 7

_________________ in all species usually metastasize first to mesenteric lymph nodes and later to other lymph nodes within and outside the abdominal cavity.

Answer 7

adenocarcinoma of intestine

Question 8

Pathways of Tumor Metastasis:
3. Hematogenous

Answer 8

• Sarcoma do tend to use hematogenous route of spread more frequently than carcinoma.
• invade veins rather than do arteries

Question 9

Tumors that enter ______ ultimately enter the vena cava and lodge in lungs or enter ______ and lodge in liver.

Answer 9

veins, portal system

Question 10

Hematogenous, example:

Answer 10

Pheochromocytomas: enter adrenal veins forming large tumor masses extending into vena cava.

Question 11

Mechanisms of Invasion and Metastasis:
- Metastasis is a complex process requiring:

Answer 11

1. Invasion of extracellular matrix (ECM).
   
   2. Entry into blood vascular or lymphatic vessels.
   3. Extravasation of tumor cells.
   4. Colonization of metastatic site.

Question 12

Mechanisms of Invasion and Metastasis:
- Adhesion: First event in invasion and metastasis.

Answer 12

Tumor cells must detach from main tumor mass, penetrate basement membrane, and enter ECM.

Question 13

In many tumor cells of epithelium, this occurs because of loss of ________ or ______ function which are essential structural elements of intercellular junctions.

Answer 13

cadherin, catenin

Question 14

________ and other specific receptors on tumor cell membrane recognize and bind to a variety of ECM components such as (fibronectin, laminin, collagen, and vitronectin)

Answer 14

Integrins

Question 15

Nonneoplastic epithelial cells generally rest on basement membranes to which they firmly attached by ______________

Answer 15

hemidesmosomes

Question 16

Tumor cells degrade basement membrane and ECM by increasing net ___________ activity in their vicinity.

Answer 16

protease

Question 17

Proteases that play important role in tumor metastasis include matrix __________ such as: type IV collagenase and urokinase.

Answer 17

metalloproteinase

Question 18

This _________ appears to be mediated by coordinated alterations in cytoskeleton and cellular adhesion structures with which they intimately associated.

Answer 18

migration

Question 19

Tumor cell migration is stimulated by:

Answer 19

1.Autocrine growth factors such as: hepatocyte growth factor, also called (scatter factor).
2. Cleavage ECM components including fragments of collagen.

Question 20

__________ actually protect tumor embolus and enhance tumor metastasis.

Answer 20

Platelets

Question 21

Some tumors preferentially metastasize to specific sites, example: _________ in human and dogs spread to bones

Answer 21

prostate carcinoma