NCCN Guidelines for Patients
Colon Cancer, Version 1.2014
Colon cancer basics
How colon cancer starts and spreads
Doctors also assess the shape of a polyp. Flat polyps
grow flush along the colon wall. They can be hard to
spot during an exam. Sessile polyps are raised above
the colon wall but don’t have a stalk. Pedunculated
polyps are shaped like mushrooms. They have
a stalk and round top. Serrated is a term for any
polyp that has a saw-tooth pattern. Sessile serrated
adenomatous polyps are rare but have been linked to
Cancer cells don’t behave like normal cells in three
key ways. First, the changes in genes cause normal
colon cells to grow more quickly and live longer.
Normal cells divide and multiply when new cells are
needed, but otherwise live in a resting state. They
also die when old or damaged. In contrast, cancer
cells make new cells that aren’t needed and don’t die
quickly when old or damaged. Over time, cancer cells
form a mass called the primary tumor.
The second way cancer cells differ from normal cells
is that they can grow into (invade) nearby tissues. If
not treated, the primary tumor will likely grow through
the colon wall. Colon cancer that has grown into the
colon wall is called invasive cancer.
Third, unlike normal cells, cancer cells don’t stay in
place. They can spread to other parts of the body.
This process is called metastasis. Colon cancer can
spread through blood or lymph vessels that are in
the submucosa. Metastases can occur in nearby or
The uncontrolled growth and spread of cancer makes
it dangerous. Cancer cells replace normal cells and
can cause organs to stop working. Thus, doctors are
searching for better ways to find and treat cancer. The
cancer tests and treatments discussed in this book
are the most current standards of practice.