For colon carcinoma, local as well as distant recurrences remain a major problem, even with the introduction of new treatment modalities. Dissemination of cancer cells in the peritoneal cavity as well as in primary tumor drainage and peripheral blood vessels during operation plays an important role in the metastasis process.
The process of hematogenous metastasis is a multistep event in which tumor cells first have to detach from the primary tumor, then invade the blood circulation where they must escape from immunological control and mechanical disruption, and subsequently adhere to the endothelium within a distant organ and finally invade and multiply to form a metastasis (Figure 1).
Metastasizing tumor cells have to proceed through all of these sequential steps to form metastases.
During this process, tumor cells circulate in the vascula-ture where they encounter host defense mechanisms. Furthermore, the life span of circulating tumor cells is limited. If tumor cells do not adhere to and migrate through the endothelium within a certain time, they will not survive. Taken together, hematogenous metastasis appears to be highly inefficient.
Although under normal conditions tumor cell arrest in distant organs is negligible, clinical and experimental observations indicate preferential tumor cell arrest at sites of injury, healing, and inflammation . Further clinical observations gave the impression of accelerated metastasis to distant organs after surgical trauma.
Abdominal surgery associated with major tissue injury provokes an inflammatory reaction with release of these proinflammatory cytokines, not only locally, but also systemically.
The systemically presence of the proinflammatory cytokines after surgery may be related with apparent accelerated metastasis to distant organs after surgical trauma. Intentionally curative resection of gastrointestinal carcinomas may therefore involve a serious risk of developing metastases. Several studies on this topic have been performed, some regarding in vitro studies and others in vivo studies. In the following section we will give an overview of these studies.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.