According to the article, a reappearing lesion is not PD if the prior patient ‘status’ was PR or SD. Does ‘prior patient status’ refer to the target lesion assessment or the overall response. Prior status refers to the overall response, not each lesion alone.

In case there is only 1 target lesion, with no non-target lesions, if the target lesion disappears and then re-appears, this would be considered to be PD, providing that if the lesion is a node, it was ≥ 10 mm (i.e malignant).  However, a single target lesion that disappears and reappears, in the presence of stable non target lesions, would not be considered PD.