During pelvic radiotherapy

Radiotherapy aimed at the pelvis passes through healthy bowel on its way to the target. The lining of that bowel is made of fast-dividing cells, which is exactly what radiotherapy acts on, so it becomes inflamed. The result can be urgency, frequency, cramping, loose stools and soreness. Doctors call it radiation enteritis or proctitis depending on where it sits.

What the guidance emphasises

Three things layered together, which is what makes this situation different. Low residue, as elsewhere in this book. Lower fat, because fat that is poorly absorbed adds to diarrhoea. And, for some people, less lactose, because an irritated small bowel temporarily makes less of the enzyme that digests it.

That second point sits awkwardly beside the rest of this book, which leans hard on butter and cream to keep energy up. Which way you go is a judgement your team makes with you rather than one a recipe can make.

Symptoms often carry on for some weeks after treatment finishes before they start to settle. A small number of people develop longer-lasting effects, and that is followed up rather than managed from a kitchen.

The research behind this book found something else worth saying plainly. There is early work asking whether more fibre, not less, might reduce radiotherapy bowel toxicity. It is unsettled, it has not changed any guidance yet, and it is a reminder of how thin the ground is under all of this. See the evidence.

What this book does

Recipes tagged for pelvic radiotherapy are smooth, mild and small. Where a dish is heavy on milk, the recipe says so, so that a lactose-free version is an easy swap. See milk and lactose.

How long

Through treatment and for some weeks afterwards, with your oncology team and dietitian deciding when to ease off and how quickly.

Bleeding, severe pain, vomiting or a sudden change in bowel habit during radiotherapy are for your treatment team the same day, not for a cookbook.