# Tumour hypoxia: imaging and modification

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

## TL;DR

Cells short of oxygen are up to three times harder to kill with radiation. Finding hypoxic tumours and fixing the shortage, with drugs, breathing gases or dose escalation, is one of radiobiology's oldest ideas and still unfinished business.

## Summary

Gray and colleagues showed in 1953 that oxygen is needed to fix radiation damage in DNA, and hypoxic regions in bulky tumours have been blamed for treatment failure ever since. Attempts to fix it include hyperbaric oxygen, carbogen and nicotinamide breathing (the ARCON approach), hypoxic cell sensitisers such as nimorazole, hypoxia-activated prodrugs such as evofosfamide (which failed in phase 3), and hyperthermia. PET tracers such as FMISO and FAZA map hypoxia, and gene signatures now select patients in trials; dose-painting the hypoxic subvolume is being tested in head and neck cancer.

## Fields

- Kind: Technology
- Status: emerging
- Last checked: 2026-09-16
- Tags: radiation-wave1
- Principle: Oxygen makes radiation damage permanent, so hypoxic cells survive; measuring hypoxia and raising oxygen delivery or mimicking oxygen's action restores radiosensitivity.
- Since: 1953
- Strengths: Strong biological rationale; Imaging can select patients; Nimorazole benefit shown in randomised trials
- Limitations: Most hypoxia drugs failed in phase 3; Hypoxia is dynamic and patchy; Imaging not yet routine

## Sources

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

## Connected records

- cancers: [Cervical cancer](https://onco.cc/cancers/cervical/), [Glioma & glioblastoma](https://onco.cc/cancers/glioblastoma/), [Head and neck squamous cell carcinoma](https://onco.cc/cancers/head-and-neck/)
- fronts: [Radiation Therapy](https://onco.cc/fronts/radiation/)
- technologies: [Hyperthermia](https://onco.cc/technologies/hyperthermia/), [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [PET (positron emission tomography)](https://onco.cc/technologies/pet/)
- terms: [Oxygen enhancement ratio](https://onco.cc/terms/oxygen-enhancement-ratio/), [Tumour hypoxia](https://onco.cc/terms/tumour-hypoxia/)
- trials: [DAHANCA 5](https://onco.cc/trials/dahanca-5/)
- drugs: [Evofosfamide](https://onco.cc/drugs/evofosfamide/), [Nimorazole](https://onco.cc/drugs/nimorazole/)

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