Real-World Tumor Response and Duration of Response

Definition and scope

Operational oncology outcomes describing response under an explicit assessment system and time from response to progression or death under a prespecified duration definition; routine clinician assessments are not automatically RECIST assessments. The target population, use, and analysis remain protocol decisions; this card explains the choices and their consequences rather than approving a study.

Operational specification

Specify eligible/evaluable population, baseline disease assessment, measurable disease if required, target/non-target lesions, assessment dates, response system, confirmation, best response window, progression/death rules, and missing or unevaluable assessments. Separate abstracted clinician-assessed response from independently reviewed RECIST response. Duration of response begins at the qualifying response, not automatically treatment initiation.

Analysis and diagnostics

For response proportions, report the analysis denominator and reasons for nonevaluation. For duration, restrict to the explicitly defined responder population and handle interval-observed progression and death according to the endpoint. A responder-only duration comparison is subject to post-treatment selection and is not automatically a causal treatment contrast.

When NOT to use and common errors

Do not label any radiology mention of improvement as a RECIST partial response, define response using future survivorship without accounting for the analysis, omit unevaluable patients from the denominator without naming the target, or use a routine visit date as the exact biological progression time.

Worked example and implementation boundary

A synthetic cohort has 40 qualifying responses among 100 eligible treated patients; only 80 have evaluable assessments. Calculate the all-eligible response proportion and report the alternative denominator separately. The all-eligible response proportion is 0.40; among the 80 evaluable patients it would be 0.50. These are different denominator-defined summaries. The code performs that explicitly stated calculation with synthetic inputs. It is not a complete fitted analysis and does not demonstrate the identification assumptions, estimate sampling uncertainty, or certify application in another population.

Data-source and reporting requirements

Preserve the provenance, dates, units, and observation rule for each input. Claims capture services and transactions under observable benefits; absence of a record is not proof that an event or resource use did not occur. EHR and registry measurements depend on the collection process and may miss care outside the system. Linked sources add reconciliation and selection questions. Primary collection can improve a missing domain but still requires valid measurement and follow-up. Report which of these limitations affects the stated use, which evidence supports the chosen inputs, and what remains uncertain.

Worked example

Scenario

A synthetic cohort has 40 qualifying responses among 100 eligible treated patients; only 80 have evaluable assessments. Calculate the all-eligible response proportion and report the alternative denominator separately.

Dataset

Synthetic inputs with units defined in the scenario; no patient data.

Steps

Result

The all-eligible response proportion is 0.40; among the 80 evaluable patients it would be 0.50. These are different denominator-defined summaries.

Trade-offs

Code example

responders = 40
eligible = 100
result = responders/eligible
assert abs(result - 0.4) < 1e-9
print(result)

responders <- 40
eligible <- 100
result <- responders/eligible
stopifnot(abs(result - 0.4) < 1e-9)
print(result)

data worked_example;
  responders = 40;
  eligible = 100;
  result = responders/eligible;
  put result=;
run;

Citations

1. [1]Eisenhauer E, et al. New response evaluation criteria in solid tumours: Revised RECIST guideline (version 1.1). European Journal of Cancer. 2009.
2. [2]U.S. Food and Drug Administration. Patient-Focused Drug Development: Selecting, Developing, or Modifying Fit-for-Purpose Clinical Outcome Assessments. Final guidance. October 2025.