# Dose reduction, interruption and discontinuation

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

## TL;DR

The everyday tools for living with side effects: pausing a drug until a problem settles (interruption), restarting at a lower dose (reduction), or stopping it for good (discontinuation). Between 30 and 60% of patients on oral targeted drugs need a reduction, so these rates are the clearest test of whether a dose was set right.

## Summary

Labels specify dose modification rules by toxicity grade; in practice 30-60% of patients on oral targeted drugs need a reduction, and discontinuation for adverse events (typically 5-20% in trials, higher in real-world older populations) directly reduces benefit. Relative dose intensity below 85% is associated with worse outcomes for curative chemotherapy, whereas for targeted drugs lower doses often work as well (Project Optimus's rationale). Adherence to daily pills over years (endocrine therapy, imatinib) is a hidden determinant of efficacy. Trials report dose reductions and discontinuations alongside grade 3-4 events as the clearest summary of tolerability.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: dose reduction; dose reductions; dose-reduction; dose reduced; dose interruption; dose interruptions; dose delay; dose delays; treatment delay; dose hold; hold treatment; dose modification; dose modifications; dose adjustment; dose adjustments; discontinuation; discontinuations; discontinued; treatment discontinuation; discontinuation rate; discontinuation due to adverse events; permanent discontinuation; stopped treatment; treatment cessation; relative dose intensity; RDI; adherence; non-adherence; compliance; real-world dosing; starting dose; dose holds; treatment delays

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Dose_(biochemistry)
- Wikipedia: https://en.wikipedia.org/wiki/Dose_(biochemistry)

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