OBJECTIVES: The consideration of subgroup analyses is an emerging topic in health care evaluation. With value-for-money being an important issue, alongside the question “is this therapy effective?”, another question becoming more relevant is “in whom is this therapy effective?” This issue is particularly relevant to the development of cancer treatments, which are often expensive and indicated in small patient populations. The use of personalised medicine is therefore expected to play a large role in this disease area. The aim of this study was to investigate how the proportion of cancer trials taking personalised medicine into account has changed over time. METHODS: ClinicalTrials.gov was searched for all interventional cancer trials that considered the use of individualised medicine, by using search terms including ‘diagnostic’, ‘prognostic’ and ‘biomarker’. Search results were de-duplicated, and the start dates of these trials were analysed and compared to those of all interventional cancer trials listed on ClinicalTrials.gov. RESULTS: In total, 2810 cancer trials considered personalised medicine. The distribution of these was strongly skewed towards recent years, with only 57 of the trials identified having started before 2000. Across all cancer trials, 2.5% of those started before 2000 considered personalised medicine, whereas this percentage increased to 13.6% after this date. Interestingly, 20.6% of cancer trials commencing in 2010, compared to 17.0% of those in 2011, involved individualised medicine, indicating that there might be a slight decline in the investigation of personalised medicine recently. Trials considering individualised medicine were most often conducted in the United States or Europe, and in disease areas such as leukaemia, head and neck, brain, and prostate cancer. CONCLUSIONS: Personalised medicine has started to play a bigger role in cancer therapy development since the year 2000. With the current health care market focusing on value-for-money, however, it is surprising that only one-fifth of recent trials considered this issue.