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  • Spread of tumors to distant locations is of great importance in cancer

  • About ninety percent of the deaths due to cancer

  • involve tumors that have spread around the body. The movement of tumor cells to

  • other parts of the body

  • is known as metastasis. Metastasis is a complex process

  • During which cancer cells break off the original

  • or primary tumor and move through the body to form tumors at new locations

  • From the point of view of a cancer cell, this is a dangerous

  • and often unsuccessful process A trip through the body is full of hazards that

  • cause the death of most cells that begin the journey

  • even tough cancer cells. To begin the process

  • individual cells must break away from the tumor and invade nearby vessels

  • The cells crawl along the surface of other cells

  • and the fibrous stringy structures surrounding them

  • and then force their way in. Shown here

  • is the invasion of the blood supply. Once inside a blood vessel,

  • the cancer cells may parish from a variety of causes

  • Some cells die simply because they are unable to survive

  • floating around in the bloodstream.

  • Others may become damaged and die when they squeeze through tight spaces

  • or bump into the walls of the blood

  • vessels.

  • Still other migrating cells may be recognized and destroyed

  • by cells of the immune system.

  • How and where the migrating cells stop is different for different cancer types

  • Once the tumor cells are no longer moving

  • they can begin the process of forming a new tumor

  • by leaving the blood vessel and beginning to reproduce in the new

  • location

  • This does not always occur and cells that have made it this far may still die

  • or fail to divide If the new environment

  • is suitable the newly-arrived cell will begin to grow

  • and a new tumor will develop.

Spread of tumors to distant locations is of great importance in cancer

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轉移 (Metastasis)

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    Study English 發佈於 2021 年 01 月 14 日
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