RECIST 1.0:

• Not specifically addressed but see EORTC – RECIST Questions and Answers (www.EORTC.be/recist/) “If you are definitely sure on previous images (with the same technique) that this lesion was absent then do not hesitate to conclude progression.”

RECIST 1.1:

• In the setting of PR (or SD), if a lesion disappears and reappears at a subsequent time point it should continue to be measured. Response will depend upon the status of his/her other lesions. The lesion should simply be added into the sum.
• In the setting of CR, reappearance of a lesion would be considered PD.
  • Most lesions do not actually ‘disappear’ but are not visualized because they are beyond the resolving power of the imaging modality employed.