Scenario:
patient was confirmed to have no brain lesions at baseline.  iUPD is assigned at timepoint 3 due to new liver lesions.  14 days later the patient has an unscheduled CT scan for new symptoms which shows a new lesion in new site.  4.5 weeks after the iUPD was first documented repeat imaging shows a further new liver lesion and increase in size of the original new lesion by more than 5mm.

Question:
Can the scan done after only two weeks be used to assign iCPD?

Answer:
in order to be consistent in the implementation of iRECIST, scans done prior to 4 weeks after 1^st iUPD (with a protocol defined variance permitted of a recommended +/- 2 days) should not be used to define iCPD UNLESS

• the scans were also performed to investigate a new clinical symptom or sign AND
• an (additional)new lesion is identified on scans done out of schedule. Increases in size of existing lesions (including new lesions identified at the time of iUPD) would not allow iCPD to be assigned and the scans should be repeated to fulfill the requirement of 4-8 weeks after the initial iUPD.

Scans done less than 4 weeks after the initial iUPD (for e.g.  in error or done for other reasons such as possible pulmonary embolus) should be disregarded and repeated as recommended 4-8 weeks after the initial iUPD.