Background: Cancer drug launch prices have increased in recent years. However, it is not fully understood how individual drug prices change over time following launch. For example, following the approval of imatinib, the price had increased threefold over a decade. The objective of this study was to measure the price trajectory of 10 cancer drugs following their launch into the US marketplace. Methods: We studied the quarterly changes in prices of average monthly doses for a cohort of 10 patented IV cancer drugs that were approved by the FDA between 1997 and 2012. In order to account for discounts and rebates, we used the Average Sales Price (ASP) published by the Center for Medicare and Medicaid Services (CMS). US inflation rates were obtained from the United States Department of Labor, and prices were adjusted for inflation. For each drug we calculated the cumulative drug price change. Data was analyzed using IBM SPSS Statistics software. Results: With an average follow-up period of 8 years, the median percent of price change for all drugs was 22% (range 3-74%). After adjusting for inflation, the median percent of price change was 6% (range -10-44%). Rituximab and trastuzumab follow a similar pattern in price increase over time and inflation-adjusted prices rose since approval by 44% and 40% respectively. The inflation-adjusted price of pemetrexed rose by 26%. We clustered drugs for indication, year of approval and company but did not find any significant trends. Conclusions: Cancer drug prices may change substantially following launch. Prices may increase by as much as 44% even after adjusting for inflation. When discussing value, we must take into account that prices are not always static.