CP and neoplasm: We presumed that if we combine human dsDNA, salmon sperm dsDNA and modified salmon sperm dsDNA into a single preparation, and administer this preparation once at the time point delimiting two phases of ICLs repair, NER and HR (18 h after exposure to CP), then the following events should occur: 1) native human dsDNA would prevent the completion of the NER phase in one fraction of tumor cells, and 2) the mix of salmon sperm DNA would interfere with the HR phase in cells, which somehow have succeeded in completing the NER one.