Thomas Van Hoof learned about the nuances of how some health plans cover oral chemotherapy drugs the same way most people do: He was diagnosed with cancer. The cancer was multiple myeloma, and the treatment includes Revlimid, a drug that costs roughly $120,000 a year. Revlimid is given orally, not intravenously, and the difference meant that Van Hoof's health plan would cover only half the cost. "I said, 'Huh? This is our coverage?' " Van Hoof recalled. "That's when the jaw drops to the floor. That's the shocker." The health plan covered chemotherapy drugs administered intravenously in a hospital or...