Neoplasia - Methods of spreading Flashcards
What are the methods of spreading?
- Local
- Seeding
- Metastasis
Local spreading?
Invades only the immediately surrounding tissue
Invasion & extension
Seeding spread?
Distant spread that occurs only within body cavities
Metastasis?
Distant spread (“true spreading”) through lymph or blood channels
Explain how metastasis spreads?
As tumor advances, it makes contact with surrounding structures as well as vessels. It will go into blood or lymph. It will travel with blood/lymph until it reaches an area with resistance. (For example, if blood, it will attach to epithelium) Once cells attach, they send out mediators. It will grow or die depending on the environment
What kind of spread is the following an example of?:
Tumor in stomach, drops through pores, land on other organs
Seeding
What kind of spread is the following an example of?:
If tumor was in the lungs, there is a probability of the malignant cells dropping and landing on the diaphragm
Seeding
Definition of metastasis?
Spread of malignant cells from primary to secondary site through blood and lymph.
What do malignant neoplasms continue to do until they can make contact with lymph or blood channels?
Divide and grow
Primary site (metastasis)?
Where the tumor was first formed, origin of cancer
Secondary site (metastasis)?
Where the CA cells spread to and proliferate
Sentinel lymph node?
first lymph node affected by cancerous cells
Does the tissue on the secondary site (metastasized site) become malignant?
No, but it is invaded by malignant cells from the primary site and gives them an area to grow and divide.
Where do malignant cells usually metastasize to?
Liver, lungs, bone, brain (vital organs)
In a nut shell, what occurs in Stage 1?
Malignant cells secrete enzymes -> destruction
Explain in detail what occurs in Stage 1?
Malignant cells begin to proliferate in local tissue [as they secrete enzymes that break up the cementing material between normal cells to make room for further proliferation]. Groups of malignant cells (emboli) enter blood or lymph vessels. Turbulence of blood distributes the cancer cells within the vessel. Defense cells attack cancer cells but approximately 1 out of every 10 000 cancer cells survive.
What distributes the cancer cells within a blood vessel?
Turbulence of blood
What aids survival of cancer cells?
Our own platelets, that cover the cancer cells and protect them from defenses.
Why do malignant cells typically have a poor survival in stage 1?
- Poor probability because it is getting into circulation. They encounter defense cells right away and are targeted.
- Turbulences
- If they go into a lymph vessel -> they go into a lump node (survival is very poor)
In a nut shell, what occurs in Stage 2?
Some emboli have entered / attachment & growth at secondary site.
Explain in detail what occurs in Stage 2?
Cancer spreads via. blood or lymph. Malignant cells arrive at a suitable secondary site. Cytokines help determine suitability and assist in growth. Once a suitable site is established, malignant cells use cytokines and growth factors to invade the tissue. Cells @ secondary site do not become malignant but they provide a safe space for the invading malignant cells to grow.
To be a suitable secondary site (metastasis), what must it provide?
- resources for growth and division
- protection from defenses
- room to grow
What is the role of cytokines in stage 2?
They help determine suitability and assist in growth (area of resistance)
Scenario: Cancer in lung -> Epithelial cells are malignant. If the cancer spreads to the liver, what occurs to the hepatocytes?
They do no become malignant however, that site provides and area for the epithelial cells to proliferate.
In a nut shell, what occurs in Stage 3?
Cells grow & cause angiogenesis in host
Explain in detail what occurs in Stage 3?
Angiogenesis occurs in host. Cancer cells need blood supply and resources to ensure survival and cell growth @ the secondary sites so they create their own blood vessels.
What is the difference between thrombosis and embolism?
Thrombosis is a blood clot in vessels that is stationary. Embolism is a piece of thrombosis that breaks off and moves with blood. (Embolism is not supposed to be here but moves with blood)
When does the secondary site become the preferred site (metastasis)?
If it is 1. Large
2. Richly vascularized
What makes suitable secondary sites?
Lungs, liver, bone (skeleton), brain [because they are all large and have vast blood supply]
