The more appropriate question might be "Can it harm normal body cells?" And the answer is "absolutely!" If you can destroy a cancer cell you can certainly kill a "normal" cell too - it's all about frequency and power.

In the ideal world, the machine will only affect the cell or pathogen that the frequency is targeted at and the "norma" cell will have a different frequency than the cancer cell. However, like a radio, if you raise the power enough then you are going to get crossover (or breakthrough) and if a normal cell has a life frequency that is close to that of a cancer cell for example, then with enough power it is possible to harm the normal cell in the process of destroying the cancer cell.

The moral of the story being - use the power (especially of the GB4000) with reasonable caution.