More muscle on planning CT was linked to better survival after head and neck radiotherapy

Design

Single-centre retrospective cohort

Population

1,187 patients receiving definitive radiotherapy for head and neck cancer (659 with CT body composition)

Primary outcome

Overall survival

Effect

High skeletal muscle HR 0.67 (95% CI 0.50 to 0.89); intermuscular fat HR 1.28 (1.03 to 1.58)

This single-centre retrospective cohort included 1,187 patients having conventionally fractionated definitive radiotherapy for head and neck cancer between 2014 and 2024. In 659, an automated deep learning tool measured muscle and fat volumes on the routine radiotherapy planning CT.

Higher BMI was associated with better overall survival (overweight HR 0.70; obesity HR 0.67), but the extra weight was mostly subcutaneous fat rather than muscle. On CT, more skeletal muscle was associated with better survival (HR 0.67, 95% CI 0.50 to 0.89), while more fat within muscle was associated with worse survival (HR 1.28, 95% CI 1.03 to 1.58).

This is association, and it does not show that building muscle changes survival. But it reinforces that weight alone is a poor guide in head and neck cancer, where weight loss and muscle wasting during treatment are common. Planning CT is already available for every patient, so muscle can be measured without extra imaging if the tools are in place.

• Assess nutrition and muscle, not just weight, before head and neck radiotherapy.
• Refer early to dietetics, especially when swallowing is already affected.
• Monitor weight weekly during radiotherapy and act early on loss.
• Do not be reassured by a normal or high BMI if muscle appears depleted.

Why it matters

A heavier patient can still be muscle-depleted, and muscle, not fat, tracked with survival here.

Don't overread it

This is a single-centre observational study; it does not show that improving muscle mass improves survival.

The statistics, in plain English

A hazard ratio of 0.67 means a lower risk of death at any time point, by about a third, for patients with more muscle. The 1.28 for intramuscular fat means about 28% higher risk. Both intervals exclude no effect, but confounding by frailty and disease stage is possible.

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