My Mother Who Is 86 Yrs Old Has A Big

My mother who is 86 yrs old has a big lump or mass in the upper right quadrant we had it ct scanned and the results says as probable sarcoma my mother does not want to have a biopsy or operation but is that the only way to know if it is malignant ? Now i notices it has grown bigger but she does not feel any pain what can we expect to happen due to this and can this lead to death?