Thanks for a great question.
Can you hurt yourself by listening to the cancer imagery? I doubt it. But is it a good idea? I doubt that too.
Why not listen to the General Wellness imagery or the Healthy Immune System imagery instead, while undergoing your tests and waiting for your results? Both have images of the body getting rid of unhealthy cells, but in the context of health and wellness.
The fact is, our bodies are continually getting rid of spontaneously formed, mutant cancer cells, way before they can become anything that's even close to a detectable critical mass that can do damage. That's just business as usual for a body!
So why not focus on healthy body processes that don't require you to label yourself a cancer patient? At this point, this is not part of your identity, and for all we know, it may never be. One step at a time!
If it does turn out that this is cancer, you'll deal with it with the same resourcefulness and energy that you're demonstrating here. Plus, you'll have already developed skillfulness in responding to guided imagery, which you can apply to more targeted cancer imagery that you can use alongside other treatments and tools.
But if it's not necessary, don't make cancer your identity.
Wishing you all the best,