In the main article on page 233 the definition of SD is written as “Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum diameters while on study.”
It should be read as: “Neither sufficient shrinkage (compared to baseline) to qualify for PR nor sufficient increase (taking as reference the smallest sum diameters while on study) to qualify for PD.
A confirmed PR at a next visit is considered to be a continuing PR unless the criteria for PD are met – the subsequent response is not based on the change from baseline but the change from the nadir.
For instance if the sum of longest diameters is 165 mm at baseline, 63 mm at week 8 and 65 mm at week 16, the target lesion response at week 16 is continued partial response.
However, for non-randomised studies, PRs must be confirmed after 4 weeks. In this example, if the study is randomized and PR was confirmed at 12 weeks, the response at 16 weeks would be ongoing PR. In the case of a non-randomized trial, if the criteria for PR are only just met at the first assessment, and are clearly not met on the confirmatory scan, it is suggested that the imaging be carefully reviewed to clarify the best response. This is an ongoing PR as the criteria for progression have not been met.