HOW DOES CANCERS SPREAD

How does cancer spread?
The onset of cancer usually begins as a solitary tumor in a specific area of the
body. If the tumor is not removed, cancer has the ability to spread to nearby organs
as well as places far away from the origin, such as the brain. So How does cancer
move to new areas and Why are some organs more likely to get infected than
others. The process of cancer spread in across the body known as Metastasis. It
begins when cancer cells from the initial tumor invade nearby normal tissue as the
cells proliferate, they spread via one of three common routes metastasis:
transcoelomic, lymphatic, hematogenous spread. In transcoelomic spread,
malignant cells penetrate the covering surfaces of cavity in our body. These
surfaces are known as peritoneum and serve as walls to segment the body cavity.
Malignant cells in ovarian cancer, for example, spread through peritoneum which
connects the ovaries to the liver, resulting in metastasis on the liver surface. Next,
cancerous cells invade blood vessels when they undergo hematogenous spread. As
there are blood vessels almost every where in the body, malignant cells utilize it to
reach more distance parts of the body. Finally, lymphatic spread ocurs when cancer
invades the lymphnodes and travels to the other parts of the body via the lymphatic
system. As this system drains many parts of the body, it also provides a large
network for the cancer. In addition, the lymphatic vessels empty into the blood
circulation alow the malignant cells to undergo hematogenous spread. Once at a
new site, the cells once again undergo proliferation and form small tumors known
as Micrometastases. These small tumors then grow into full-fledged tumors and
complete the metastatic process. Different cancers have been known to have
specific sites of metastasis. For example, prostate cancer commonly metastasizes
to the bone while colon cancer metastasizes to the liver. Very theories have been
proposed to explain the migration pattern of malignant cells. Of particular interest


are two conflicting theories. Stephen Paget, an English surgeon came up with the
seed and soil theory of metastasis. The seed and soil theory states that cancer cells
die easily in the wrong microenviroment. Hence, they only metastasize to a

location with similar characteristics. However, James Ewing, the first professor of
pathology of Cornell University, challenged the seed and soil theory and proposed
that the site of metastasis was determined by the location of the vascular and
lymphatic channels which drain the primary tumor. Patients with primary tumors
that were drained by vessels leading to the lung would eventually develop lung
metastasis. Today, we know that both theories contain valuable truths. Yet the full
stories of the metastass is much more complicated than either of the tow proposed
theories. Factors like the cancer cell’s properties and the effectiveness immune
system in eliminating the cancer cells, also play a role in determining the success
of metastasis. Unfortunately, many questions about metastasis remain unanswered
until today. Understanding the exact the mechanism holds an important key to
finding a cure for advanced stage cancers. By studing both the genetic and
enviromental factors which contribute to successful matastasis, we can pinpoint
way to shut down the process. The war against cancer is a constant struggle and
scientists are hard at work developing new methods against metastasis. Of recent
interest is immunotherapy, a modality which involves harnessing the power of the
immune system to destroy the migrating cells. This can be done in different ways,
such as training immune cells to recognize cancerous cells via vaccines. The
growth and activity of the immune cells can also be stimulated by injecting manmade interleukins, chemicals which are usually secreted by the immune cells of the
body. These two treatments are only the tip of the iceberg. With the collaborated
research efforts of goverments, companies and scientists, perhaps the process of
metastasis will be stoped for good.