Author: Robert Nussbaum Medical Geneticist The University of California, San Francisco
2008-07-28
2008-07-28
What is Cancer?
Cancer is not a single disease, but rather, is the name used to describe the most dangerous form of neoplasia,
a disease process characterized by abnormal, uncontrolled cell division
leading to a mass or tumor. Uncontrolled growth alone, however, does
not make a tumor a cancer. For a tumor to be a cancer, it must not only
grow inappropriately at the site where it originates (the primary) but
must also demonstrate malignant behavior, that is, the capacity to
invade normal tissues neighboring the site of the primary tumor and/or
to seed new tumors at distant sites in the body (metastases). The
surrounding normal tissue is also likely to play an important role, by
providing the blood supply that nourishes the tumor, by permitting
cancer cells to escape from the tumor and form metastases, and by
shielding the tumor from attack by the body’s own defense mechanisms.
Thus, cancer is a complex process, both within the tumor and between the
tumor and the normal tissues that surround it.