Specific biotech anticancer drugs attack cancer cells essentially by blocking carcinogenic enzymatic cascades or carcinogenic membrane receptors, but respect DNA.
Classical anticancer chemotherapy, on the contrary, targets DNA.
Other biotech medicines are used in oncology, either to lessen some side-effects of chemotherapy (G-CSF is used for instance to fight neutropenia), which allows better tolerability of standard doses, or dose increase, or for their original anticancer effects (alpha interferon and interleukin 2 for instance)
