Although physician services represent a substantial portion of cancer care costs, little is known about trends in the costs of physician cancer services in the fee-for-service Medicare program. We analyzed aggregated data from all Part B Medicare claims for physician and supplier services attributed to cancer patients from 1999 to 2012 to characterize how billing and payments have changed over time for the most common cancer types. Billing and expenditure data are from the Medicare Statistical Supplement, and age-adjusted incidence data are from SEER. Physician services for cancer patients grew from $7.6 billion in 1999 to $12.3 billion in 2012 (60 percent increase). Reimbursements for physician and supplier services for cancer treatment in Medicare Part B beneficiaries steadily grew from 1999 to 2005 and then plateaued through 2012, led by a decrease in reimbursements for prostate cancer care. These trends may reflect shifts toward hospital-based care or changes in aggressiveness of care.