Cancer is characterized by a radical malfunction of the cells of the body, which begin to replicate uncontrollably, causing the growth of tumors. Cancer spreads very rapidly at times, with victims not realizing the extent of infection until it is too late. It also spreads, or metastasizes, in a variety of ways, including locally, through the bloodstream, and through the lymphatic system. For this reason, excision of cancerous cells is difficult, and doctors often take a large area around the cancerous tumor to prevent recurrence.
When tumors form in or on the body, medical professionals determine whether they are benign or malignant. If benign, the tumor looks unpleasant but will not spread, and does not require extensive treatment in addition to removal. If malignant, the tumor is usually termed cancerous, and is treated much more carefully to prevent catastrophic spread of the disease.
Cancer is divided into two types: primary and secondary. Primary cancer refers to the area which was first colonized by the cancer, while secondary cancer is caused by spreading. If, for example, the cancer metastasizes to the liver but originates in the stomach, it is still referred to as a stomach cancer, because this is the source of the primary cancer. It is the spreading of cancer which can be deadly, because a handful of cancer cells can wreak havoc on the body of the victim.
When cancer metastasizes through the lymph system, it takes advantage of the extensive network of lymph nodes throughout the human body. A few cells can break off from the primary cancer and circulate through the lymph system looking for a new place to settle. Consequently, most doctors will remove lymph nodes around the area of a cancer during surgery, to ensure that no cancer cells lurking in the nodes will spread after the primary tumor has been removed.
Cancer spreads through the bloodstream as well, in much the same way it distributes through the lymph system. Like all cells, cancer requires blood and oxygenation to survive, and therefore has access to the blood stream. As a result, malignant cells can be transported through the bloodstream to other parts of the body. It is far more difficult to prevent the spread of cancer through the blood stream due to the extensive network of veins in the human body.
Cancer spreads locally also, taking over and devouring neighboring healthy cells. When cancer spreads locally, it can move very slowly, as in the case of many skin cancers, or rapidly in some other parts of the body, depending upon susceptibility. Some parts of the body such as the liver and lungs are more susceptible to cancer spreads than others, and the spread of the cancer will also be influenced by what type of cancer it is.
If you are in a risk category for cancer, make sure to have regular examinations to arrest the spread of cancer early, providing the best chance of survival.