I don't know whether your diagnosis of ringworm is true, since what the layman thinks as ringworm may not be ringworm. Please consult a dermatologist for confirmation of the diagnosis.
Ringworm does not cause cancer. If your problem is that of ringworm, it can be cured by antifungal drugs. For chronic and widespread tinea, orally tablet griseofulvin, fluconazole, itraconazole or terbinafine can be used.