The prognosis for stage 4 metastatic cancer depends on a variety of factors, but some can be treated with chemotherapy, according to Oasis of Hope. One factor that greatly affects the prognosis of stage 4 metastatic cancer is how the cancer responds to chemotherapy. In some cases, the cancer will return as a chemotherapy-resistant strain that is terminal.
Metastatic cancer is cancer that has spread from the initial location, according to the National Cancer Institute. For example, the brain, bone, lung and liver are the main sites of breast cancer metastasis. The lung, liver and peritoneum are the main metastasis sites for ovarian, colorectal, stomach and pancreatic cancers.