Background: In most phase I oncology trials, it is often stated that the dose increments follow a "modified-Fibonacci sequence". This term, however, is vague.
Methods: To better characterize this sequence, we reviewed 81 phase I trials based on this concept.
Results: Out of 198 phase I oncology trials, 81 (41%) are based on modified-Fibonacci series. Actual incremental ratios varied in a large range from 0.80 to 2.08. The median of actual increments was about 2.00, 1.50, 1.33, 1.33, 1.33, 1.33, 1.30, 1.35…. The "modified Fibonacci-sequence" gathers heterogeneous variation of the genuine sequence, which does not tend to a constant number at higher dose-levels.
Conclusion: This confusing term should be avoided.