Background: Novel oral targeted drugs are being used more frequently to treat many cancers and have substantially improved clinical and survival outcomes. Due to the long treatment durations of many of these medications, which are given continuously until patient progression, per-patient lifetime costs can be high. This study aimed to identify the ten oral anticancer therapies with the highest annual Medicare Part D spending. Methods: Descriptive statistics were performed on data obtained from the CMS Medicare Part D Drug Spending Dashboard and IBM Micromedex RED BOOK, from 2018-2019. Medicare Part D dashboard includes total and average drug spending, and number of beneficiaries utilizing the drug. RED BOOK provides current and historical average wholesale pricing (AWP) data for all prescription drugs. The wholesale acquisition cost (WAC) was calculated from the AWP to evaluate trends in price. We identified the ten anticancer brand-name medications in 2019 with the highest annual Part D spending and reported changes in average spending and number of unique beneficiaries for each drug from 2018-2019. Results: In 2019, Revlimid had the highest annual total Part D spending at $4.6 billion, followed by Imbruvica with $2.4 billion; these drugs also had the greatest number of beneficiary utilizers. From 2018-2019, change in average spending per dosage unit was greatest for Zytiga (34%), however among all drugs, average spending per beneficiary in 2019 was lowest for this medication ($58,074). From 2018-2019, WAC and average spending per dosage unit increased for all of the top ten drugs, as well as the number of total beneficiaries utilizing each drug, except for Zytiga and Sprycel. Conclusions: Oral anticancer therapies provide high value for patients, including improved quality of life and survival. Annual costs for these drugs are high, however spending on inpatient hospital services remains a greater share of total Medicare spending in aggregate and on a per beneficiary basis. Emerging one-time curative treatments for cancer may prove most cost-effective in the long-term by eliminating the need for continuous medication use and hospital care, while improving patient outcomes.

* Part D drug spending divided by the number of dosage units, which is weighted by the proportion of total claims