Oncology Skews the Split

The unavoidable share is not the same everywhere

In the first article in this series, we explored how amendment rates have increased over the years. However, the data also shows that amendments are not distributed equally across disease areas. 82% of oncology amendments were classified somewhat or completely unavoidable, against 74.9% for non-oncology protocols (Botto et al., 2024). A cause filed as unavoidable in one disease area was filed as avoidable more often in another, under the exact same rules.

Oncology protocols also carried more endpoints and more countries on average than non-oncology protocols, and were more likely to use master protocol or adaptive designs, structures built to test several hypotheses or adjust mid-trial (Botto et al., 2024). Complexity and the unavoidable label appear to move together here, not apart.

One result runs against the obvious explanation. Oncology protocols are known for narrow, tightly defined eligibility criteria, yet recruitment difficulty was cited less often as the primary cause of an oncology amendment than a non-oncology one, 2.3% versus 4.5%. Botto et al. (2024) suggest recruitment problems in oncology are more often bundled into a different primary cause on the same form, not absent, just recorded elsewhere.