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NCCN Guidelines for Patients


Stomach Cancer, Version 1.2016

1 Stomach cancer basics

Cancer's threat

Cancer’s threat

Cancer cells don’t behave like normal cells in three

key ways. First, mutations in genes cause cells to

grow more quickly and live longer. Normal cells grow

and then divide to form new cells when needed. They

also die when old or damaged as shown in

Figure 3


In contrast, cancer cells make new cells that aren’t

needed and don’t die quickly when old or damaged.

Over time, stomach cancer cells form a mass called

the primary tumor.

The second way cancer cells differ from normal

cells is that they can grow into nearby tissues. If not

treated, the primary tumor can extend beyond the

wall of the stomach and into nearby structures. The

nearby structures into which stomach tumors grow

are described in

Part 2 Cancer staging.

Third, unlike normal cells, cancer cells can travel

to other parts of the body. This process is called

metastasis. In this process, cancer cells break away

from the tumor and merge with blood or lymph. Then,

the cancer cells travel in blood or lymph through

vessels to other sites. In other sites, the cancer cells

may form secondary tumors, replace many normal

cells, and cause major health problems.

Illustration Copyright © 2016 Nucleus Medical Media, All rights reserved.

Figure 3.

Normal cell growth vs.

cancer cell growth

Normal cells increase in number

when they are needed and die

when old or damaged. In contrast,

cancer cells quickly make new

cells and live longer because of

abnormal changes in genes.