Cancer Drug Coverage Act of 2018 This bill requires health plans that cover anticancer medications administered by a health care provider to provide no less favorable cost sharing for patient-administered anticancer medications. This requirement applies to medications that are (1) approved by the Food and Drug Administration; (2) medically necessary for the cancer treatment; and (3) clinically appropriate in terms of type, frequency, extent site, and duration. To comply with this requirement, health plans may not, with respect to anticancer medications (1) change or replace benefits to increase out-of-pocket costs, (2) reclassify benefits to increase costs, or (3) apply more restrictive limitations to orally administered medications than to intravenously administered or injected medications.