Cancer, or malignant tumors, may arise anywhere in the body. The presentations and symptoms differ according to the site of cancer. However, as the disease progresses, the complications arising from an advanced cancer are very similar regardless of the site of origin. Cancers spread to vital organs, triggering a sequence of events leading up to the person's death.

Metastasis is the spread of cancer cells from the original site of cancer to other distant organs and tissues. This spread usually occurs when the tumor cells gain access to blood or lymph vessels where they circulate and then settle in an organ. After the seedling cancer cells settle, they start to divide and form new growths. Metastasis is the leading cause of death from cancer. Some of the common sites of metastatic growths are the lung, liver, bones of the pelvis and the spine, and the brain.

One of the most common terminal stages of cancer is cachexia. This condition is the extreme wasting -- weight loss -- observed in people with advanced cancer. Wasting is the loss of lean muscle mass and other leans tissues in the body. Although cachexia is commonly associated with loss of appetite, it is not directly caused by a decrease in nutrient intake -- people who receive supplemental feeding sometimes suffer from cachexia. While sometimes appetite stimulants, such as the drug megesterol, can improve a person's appetite, they usually do not slow down the development of malignant cachexia.

Whether cancer originated in a vital organ or reached it though spread, failure of an affected organ is unavoidable. Also, kidney failure in terminal stages of cancer is a very common occurrence. Renal failure may be caused by mechanisms related to the cancer itself or by the chemotherapy treatments -- toxic to the kidney -- received to eradicate the cancer.