Cancer starts when cells in the
body change (mutate) and grow out of control. To help you understand what happens
when
you have cancer, let’s look at how your body works normally.

Your body is made up of tiny
building blocks called cells. Normal cells grow when your body needs them, and die
when
they’re damaged or your body no longer needs them.

Cancer is made up of abnormal cells
that grow even though your body doesn’t need them. In most cancers, the abnormal cells
grow to form a lump or mass called a tumor. If cancer cells are in the body long enough,
they can grow into (invade) nearby areas. They can also spread to other parts of the
body (metastasize).

Uterine sarcoma is a very rare
cancer that starts in the thick muscular wall and supporting tissues of the uterus.
(This part of the uterus is called the myometrium.) Most uterine cancers are not uterine
sarcoma, they’re endometrial carcinomas. These cancers start in the inner lining of
the
uterus.

The uterus is an organ that’s part
of the female reproductive system. You may know it as the womb. It’s where a baby
grows
during pregnancy.

The uterus is usually pear-shaped
and about the size of a fist. It’s in the lower belly (pelvic area), between the bladder
and the rectum. The uterus is connected to the fallopian tubes. These tubes carry
eggs
from the ovaries into the uterus. The small opening that connects the uterus to the
vagina is the cervix.

The uterus is made up of 3
layers:

• Endometrium. This is the innermost lining. (It’s where endometrial cancer
  starts. This is the much more common kind of uterine cancer.)

• Myometrium. This is the middle layer of thick muscle.

• Serosa. This is the smooth outer layer that coats the uterus.

During labor, the myometrium muscle
helps push the baby out through the cervix. The smooth serosa makes it easy for the
uterus to slide and move in the pelvis as needed.

If uterine sarcoma spreads, it
tends to first go to places near the uterus. It can spread to the cervix, vagina,
ovaries, fallopian tubes, and lymph nodes. In later stages, as it grows, it can spread
to the bladder, bowel, lungs, liver, or bone. 

Cancer that spreads to other parts
of the body is called metastatic cancer. The process of spreading is called metastasis.
Metastasis is a complex process. The cancer cells of the tumor in the uterus grow
into
other tissues, blood vessels, and the lymph system. The cells then travel through
the
bloodstream or the lymph system to reach other parts of the body, where they can grow
into new tumors.

The tumors in these new areas are
still uterine sarcomas. So, when this cancer spreads to the lungs, for instance, the
cells in the lung tumor are uterine sarcoma cells, not lung cancer cells. And the
disease is called metastatic uterine sarcoma, not lung cancer.

If you have questions about
uterine sarcoma, talk with your healthcare provider. Your healthcare provider can
help
you understand more about this cancer.