Why Cancer Research?
Research is our best defense against cancer. The Nation’s
investments in cancer research and biomedical science during the
past four-plus decades have produced remarkable progress in our
understanding of the events which initiate a number of cancers at
the molecular, cellular and tissue levels. Advances in cancer
research are now transforming patient care. We would not be on
our current path to revolutionizing cancer care if not for the
extraordinary endeavors of individuals working in numerous
research disciplines and technologies.
Today, we know that because cancer is extremely heterogeneous, it
is in fact not a single disease, but likely consists of over 200
diseases. Further, we are beginning to understand that due to this
heterogeneity, nearly all cancers are comprised of a number of
different cancer subtypes, meaning that every person’s cancer is
unique in its composition. Despite the apparent complexity that this
diversity brings, decades of research have established that there
are a number of basic biological principles that underpin cancer
initiation, growth and spread to other sites in the body.
One of the most fundamental traits of cancer cells is their ability to
multiply uncontrollably. Normal cells only proliferate when the
balance of numerous factors instructs them to do so, by
progressing through a process called the cell cycle (see Fig. 2, p.
20). Various inputs determine whether or not a cell will enter this
cycle; these include the balance of growth-stimulating and growth-suppressing factors; the energy state of the cell, including nutrient
and oxygen levels; and the status of the environment that
surrounds the cell, called the microenvironment. This biological
system is dysfunctional in cancer cells.
A second characteristic central to cancer cells is their ability to
invade and destroy normal tissue surrounding them and to move to
and grow in other areas of the body, called metastasis. Metastasis
is the most lethal attribute of cancer cells. It is responsible for more
than 90% of the morbidity and mortality associated with cancer
(see Sidebar on Metastasis). Local invasion and metastasis are
complex processes, fueled by changes in the cancer cells and in
their interactions with their environments.
The development of cancer is largely due to the accumulation of
genetic changes that lead to malfunctions in the molecular
American Association for Cancer Research
Metastasis is the spread of cancer cells from a primary tumor
to other areas of the body where they establish new tumors. It
is responsible for more than 90% of the morbidity and mortality
associated with cancer. Studying the fundamental properties of
metastasis is essential to conquering cancer, because it is only
through research that we will be able to identify important
targets for the development of new therapies to prevent or treat
metastasis, and learn how to predict who will develop
metastatic cancer and require these therapies.
Already we have learned a great deal about this deadly
process, some of which explains why metastatic disease is so
difficult to treat. For example, virtually every step of the
metastatic process can be achieved through multiple different
means, giving the cancer cells many opportunities to
metastasize. This also means that blocking only one pathway
therapeutically will not be sufficient. In addition, we know that
cancer cells can travel to other parts of the body and then lie
dormant in this new location for years, becoming active again
later in life. A greater understanding of the factors that
contribute to tumor cell dormancy could lead to the
development of new therapies that have the potential to prevent
these dormant cells from reawakening.
Metastatic disease is a dire situation that requires an
immediate and complete therapeutic response in order to
prevent almost certain death. While recent research has
revealed that there is a genetic basis for susceptibility or
resistance to metastasis, creating new avenues for the
development of effective therapies, much more work is needed
if we are to develop a comprehensive understanding of this
complex process and make significant progress against cancer
and toward saving lives.
There have been
cancer deaths since 1990 and
1991 for men and women, respectively,
as a result of declining death rates.