The Impact of
Metastasis is the spread of cancer from a primary tumor to other
areas of the body where the cancer cells establish new tumors (see
Figure 5, p. 26). It is this most lethal attribute of cancer cells that is
responsible for more than 90% of the morbidity and mortality
associated with cancer. Therefore, studying the fundamental
properties of metastasis is essential to conquering cancer. Through
research, we will learn how to predict who will develop metastatic
cancer. We also need to identify important targets for the development
of new therapies that will prevent or treat metastasis.
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.
We also understand that metastasis is a distinct property of cancer
cells, not a property of all cells. Furthermore, not all cancer cells within
a metastatic tumor are capable of metastasizing, and not all cancers
become metastatic. New research has revealed that there is a genetic
basis for susceptibility or resistance to metastasis. These findings
create new avenues for effective therapies.
Another critical finding is that cancer cells can travel to other parts of
the body, and then lie dormant in a new location for years, only to
become 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. Only with continued research into this complex process can we
hope to make significant progress against cancer and save lives.