Head and neck cancer is becoming more common, with cases increasing by about 30% since the early 1990s. Treating these cancers can be difficult because of the complex structures in this area of the body and other health conditions many patients may have.

Some head and neck cancers contain areas with low oxygen levels, known as hypoxia.
These low‑oxygen areas are important because:

• Tumours with hypoxia often respond less well to radiotherapy and chemotherapy.
• They may be harder to control and can be linked with poorer outcomes.

Researchers have looked for ways to improve treatment for patients with hypoxic tumours. For example, drugs called radio‑sensitizers (such as nimorazole) can help make cancer cells more sensitive to radiotherapy. Increasing the radiotherapy dose can also help kill more cancer cells, but this can raise the risk of side effects.

Another important factor is the rise in HPV‑related head and neck cancers, which generally have a better outlook than cancers not caused by HPV. For these patients, doctors are interested in approaches that maintain excellent cancer control while reducing treatment side effects.

Understanding whether a tumour has hypoxic areas—and how much—is useful because it may allow us to:

• Adjust radiotherapy doses to target the areas that need it most
• Personalise treatment plans while reducing unnecessary side effects

To do this, non‑invasive imaging techniques that show low‑oxygen areas within the tumour (OE-MRI). are an appealing option.

What this study aims to find out

1. Is OE‑MRI safe, tolerable, and practical for patients with head and neck cancer?
2. Can OE‑MRI accurately and consistently identify low‑oxygen (hypoxic) areas in these tumours—either on its own or combined with other scans?
3. What is the best way to perform OE‑MRI scans to get reliable images?
4. How do patients respond to treatment, and what side effects or recurrences occur over time?
5. Which MRI scan settings are most useful for planning radiotherapy that adapts to each patient’s tumour?

Patients on this study will require extra study MR scans before and during radiotherapy with oxygen administered via a facemask.