There are many types of cancer that give no sign of their presence until they are far advanced, such as lung, ovary, colon, pancreas, kidney, liver and others. They are all bad. It is difficult to say that any one is the worst. To my own way of thinking, any cancer with spread to the brain is particularly frightening. Gioblastoma multiforme is a type of malignant tumor in the brain that cannot be clearly demarcated and excised as its margins are indistinct and there are tendrils of tumor that may cross resection margins.