NCCN Guidelines for Patients
: Non-Small Cell Lung Cancer
Part 1: About lung cancer
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See Part 1 on page
X for definitions of
other lung parts.
Tiny sacs in the
lungs where gases are
transferred in and out of
small airways within the
The two airways
extending from the trachea
into the lungs
A clearly seen
division in a lung
The group of organs that
transfers gases in and out
of the body
The air passage
between the throat and
bronchi; also called the
1.2 How lung cancer starts
Cancer is a disease of cells—the building blocks of tissue in the body. Inside of
cells are coded instructions, called genes, for building new cells and controlling
how cells behave. Changes in genes cause normal lung cells to become cancer
cells. Gene changes that are linked to lung cancer aren’t passed down from
parents to children (inherited) but are caused by other factors.
Almost all lung cancers are carcinomas. Carcinomas are cancers that start in
cells that line the inner or outer surfaces of the body. Lung carcinomas start in
cells that line the airways of the lungs.
Lung carcinomas are divided into two groups based on how the cells look. One
group is called small cell lung cancers and the other group is called non-small
cell lung cancers. The second group is much more common and is the focus of
1.3 How lung cancer spreads
The changes in genes cause cancer cells to make too many copies of
themselves. Normal cells grow and then divide to form new cells when needed.
They also die when old or damaged. Cancer cells don’t do this. 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. If not treated, the
primary tumor can grow large and invade other tissue like a bronchus or pleura.
Cancer cells can replace so many normal cells that it is hard to breathe.
Cancer cells can also break away from the primary tumor and form new tumors.
This process is called metastasis. These secondary tumors may form in nearby
sites, such as another lobe of the lung. Secondary tumors can also form in
distant sites, such as the other lung or the brain.