Cancer is characterized by a radical malfunction of the body's cells, which begin to replicate uncontrollably, causing the growth of tumors. Cancer spreads very quickly sometimes, and victims don't realize the extent of the infection until it's too late. Cancer spreads in various ways, including locally, through the bloodstream and through the lymphatic system. For this reason, excision of cancer 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 unsightly but will not spread, and does not require extensive treatment other than removal. If malignant, the tumor is usually called 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 that was first colonized by cancer, while secondary cancer is caused by the spread. If, for example, the cancer spreads to the liver but starts in the stomach, it is still called stomach cancer, because this is the source of the primary cancer. The spread of cancer can be deadly, because a handful of cancer cells can wreak havoc on the victim's body.
When cancer spreads through the lymphatic system, it takes advantage of the extensive network of lymph nodes throughout the human body. Some cells may break away from the primary cancer and circulate through the lymphatic system in search of a new place to settle. Consequently, most doctors will remove the lymph nodes around the cancer area during surgery, to ensure that cancer cells lurking in the nodes don't spread after the primary tumor has been removed.
Cancer also spreads through the bloodstream, in the same way that it is distributed through the lymphatic system. Like all cells, cancer requires blood and oxygenation to survive, and therefore has access to the bloodstream. As a result, malignant cells can be carried through the bloodstream to other parts of the body. It is much more difficult to prevent the spread of cancer through the bloodstream due to the extensive network of veins in the human body.
Cancer also spreads locally, taking over and devouring neighboring healthy cells. When cancer spreads locally, it can move very slowly, as is the case with many skin cancers, or quickly to other parts of the body, depending on susceptibility. Some parts of the body, such as the liver and lungs, are more susceptible to the spread of cancer than others, and the spread of cancer will also be influenced by the type of cancer.
If you are in a cancer risk category, be sure to get regular screenings to stop the cancer from spreading early, giving you the best chance of survival.