Classification of tumors, their frequency and progression

This chapter discusses how tumors are classified, their frequency (or how common they are), and their prognosis (or how they behave over time). Much of cancer prognosis is dependent on whether the cancer has metastasized. Tumor metastasis is a cancerous tumor that has spread from the place where it started to another place in the body. Even though the tumor has spread to a new area, it retains the same type of cancer cells as the original tumor and it retains the same name. When a breast cancer spreads to the bone and forms a new tumor, the new tumor is a metastatic breast cancer, not a bone cancer. The most common sites of tumor metastasis are the lung, liver, brain, and bone. Statistics that help to show the prognosis of cancer are the overall five-year survival rate, the incidence rate, and the mortality rate.