I have cancer, am i more susceptible to ecthyma gangrenosum?

Possibly: Ecthyma gangrenosum is usually seen in people with profoundly low white blood cell counts and is due to bacteria getting to the skin through the blood. These bacteria may be released more readily from areas where there is a primary malignancy. Don't confuse this with pyoderma gangrenosum, a very different illness.

I don't think so: But would check with your doctor or dermatologist.