# Partial response

Source: https://onco.cc/terms/partial-response/  
OnCo record `partial-response` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The tumours have shrunk substantially (by at least 30% in total diameter) but not disappeared. Together with complete responses it makes up a trial's response rate.

## Summary

RECIST 1.1 defines partial response as at least a 30% decrease in the sum of the longest diameters of the target lesions with no new lesions; the response must be confirmed on a later scan. Response rate (complete plus partial) is the quickest signal that a drug is active and the basis of many accelerated approvals, but shrinkage does not always translate into longer life, and some effective drugs, notably immunotherapies and some targeted agents, produce long stable disease rather than shrinkage. How long a response lasts (duration of response) is often more informative than how many patients achieve one.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: partial responses; responded; responders; responder; non-responders; non-responder; response rate; response rates; tumour shrinkage; tumor shrinkage; shrank; shrinkage; responds to; responding

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Response_evaluation_criteria_in_solid_tumors
- Wikipedia: https://en.wikipedia.org/wiki/Response_evaluation_criteria_in_solid_tumors

## Connected records

- terms: [Complete response](https://onco.cc/terms/complete-response/), [Duration of response](https://onco.cc/terms/duration-of-response/), [Objective response rate (ORR)](https://onco.cc/terms/orr/), [Progression](https://onco.cc/terms/progression/), [RECIST](https://onco.cc/terms/recist/), [Remission](https://onco.cc/terms/remission/), [Stable disease](https://onco.cc/terms/stable-disease/), [Surrogate endpoint](https://onco.cc/terms/surrogate-endpoint/)
- key papers: [Therasse 2000: RECIST, the standard rules for measuring whether a tumour responds](https://onco.cc/key-papers/paper-therasse-recist-jnci-2000/)

---
JSON: https://onco.cc/api/v1/entities/partial-response.json