That depends upon the metal you have used and also the properties of the metal
If you are using a metal which is directly attaching to the tumor cell.It can be used to kill the specific cell, but that should not attach to the normal cells.
I don't think that your sample could be used for cancer treatment. Reason being that your sample will be broadly toxic to all cells (including healthy cells), as it is not specifically targeted as a drug.
You can test your sample in vitro for particular cancer cell-lines and healthy cells and compare the results.